22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang; 27 28 import java.io.ObjectStreamClass; 29 import java.io.ObjectStreamField; 30 import java.io.UnsupportedEncodingException; 31 import java.nio.charset.Charset; 32 import java.util.ArrayList; 33 import java.util.Arrays; 34 import java.util.Comparator; 35 import java.util.Formatter; 36 import java.util.Locale; 37 import java.util.regex.Matcher; 38 import java.util.regex.Pattern; 39 import java.util.regex.PatternSyntaxException; 40 41 /** 42 * The <code>String</code> class represents character strings. All 43 * string literals in Java programs, such as <code>"abc"</code>, are 44 * implemented as instances of this class. 45 * <p> 46 * Strings are constant; their values cannot be changed after they 47 * are created. String buffers support mutable strings. 48 * Because String objects are immutable they can be shared. For example: 49 * <p><blockquote><pre> 50 * String str = "abc"; 51 * </pre></blockquote><p> 52 * is equivalent to: 53 * <p><blockquote><pre> 54 * char data[] = {'a', 'b', 'c'}; 55 * String str = new String(data); 56 * </pre></blockquote><p> 57 * Here are some more examples of how strings can be used: 58 * <p><blockquote><pre> 59 * System.out.println("abc"); 60 * String cde = "cde"; 61 * System.out.println("abc" + cde); 62 * String c = "abc".substring(2,3); 63 * String d = cde.substring(1, 2); 64 * </pre></blockquote> 65 * <p> 66 * The class <code>String</code> includes methods for examining 67 * individual characters of the sequence, for comparing strings, for 68 * searching strings, for extracting substrings, and for creating a 69 * copy of a string with all characters translated to uppercase or to 70 * lowercase. Case mapping is based on the Unicode Standard version 71 * specified by the {@link java.lang.Character Character} class. 72 * <p> 73 * The Java language provides special support for the string 74 * concatenation operator ( + ), and for conversion of 75 * other objects to strings. String concatenation is implemented 76 * through the <code>StringBuilder</code>(or <code>StringBuffer</code>) 77 * class and its <code>append</code> method. 78 * String conversions are implemented through the method 79 * <code>toString</code>, defined by <code>Object</code> and 80 * inherited by all classes in Java. For additional information on 81 * string concatenation and conversion, see Gosling, Joy, and Steele, 82 * <i>The Java Language Specification</i>. 83 * 84 * <p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor 85 * or method in this class will cause a {@link NullPointerException} to be 86 * thrown. 87 * 88 * <p>A <code>String</code> represents a string in the UTF-16 format 89 * in which <em>supplementary characters</em> are represented by <em>surrogate 90 * pairs</em> (see the section <a href="Character.html#unicode">Unicode 91 * Character Representations</a> in the <code>Character</code> class for 92 * more information). 93 * Index values refer to <code>char</code> code units, so a supplementary 94 * character uses two positions in a <code>String</code>. 95 * <p>The <code>String</code> class provides methods for dealing with 96 * Unicode code points (i.e., characters), in addition to those for 97 * dealing with Unicode code units (i.e., <code>char</code> values). 98 * 99 * @author Lee Boynton 100 * @author Arthur van Hoff 101 * @author Martin Buchholz 102 * @author Ulf Zibis 103 * @see java.lang.Object#toString() 104 * @see java.lang.StringBuffer 105 * @see java.lang.StringBuilder 106 * @see java.nio.charset.Charset 107 * @since JDK1.0 108 */ 109 110 public final class String 111 implements java.io.Serializable, Comparable<String>, CharSequence 112 { 113 /** The value is used for character storage. */ 114 private final char value[]; 115 116 /** The offset is the first index of the storage that is used. */ 117 private final int offset; 118 119 /** The count is the number of characters in the String. */ 120 private final int count; 121 122 /** Cache the hash code for the string */ 123 private int hash; // Default to 0 124 125 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 126 private static final long serialVersionUID = -6849794470754667710L; 127 128 /** 129 * Class String is special cased within the Serialization Stream Protocol. 130 * 131 * A String instance is written initially into an ObjectOutputStream in the 132 * following format: 133 * <pre> 134 * <code>TC_STRING</code> (utf String) 135 * </pre> 136 * The String is written by method <code>DataOutput.writeUTF</code>. 137 * A new handle is generated to refer to all future references to the 138 * string instance within the stream. 139 */ 140 private static final ObjectStreamField[] serialPersistentFields = 141 new ObjectStreamField[0]; 142 143 /** 144 * Initializes a newly created {@code String} object so that it represents 145 * an empty character sequence. Note that use of this constructor is 146 * unnecessary since Strings are immutable. 147 */ 148 public String() { 149 this.offset = 0; 150 this.count = 0; 151 this.value = new char[0]; 152 } 153 154 /** 155 * Initializes a newly created {@code String} object so that it represents 156 * the same sequence of characters as the argument; in other words, the 656 * @return the length of the sequence of characters represented by this 657 * object. 658 */ 659 public int length() { 660 return count; 661 } 662 663 /** 664 * Returns <tt>true</tt> if, and only if, {@link #length()} is <tt>0</tt>. 665 * 666 * @return <tt>true</tt> if {@link #length()} is <tt>0</tt>, otherwise 667 * <tt>false</tt> 668 * 669 * @since 1.6 670 */ 671 public boolean isEmpty() { 672 return count == 0; 673 } 674 675 /** 676 * Returns the <code>char</code> value at the 677 * specified index. An index ranges from <code>0</code> to 678 * <code>length() - 1</code>. The first <code>char</code> value of the sequence 679 * is at index <code>0</code>, the next at index <code>1</code>, 680 * and so on, as for array indexing. 681 * 682 * <p>If the <code>char</code> value specified by the index is a 683 * <a href="Character.html#unicode">surrogate</a>, the surrogate 684 * value is returned. 685 * 686 * @param index the index of the <code>char</code> value. 687 * @return the <code>char</code> value at the specified index of this string. 688 * The first <code>char</code> value is at index <code>0</code>. 689 * @exception IndexOutOfBoundsException if the <code>index</code> 690 * argument is negative or not less than the length of this 691 * string. 692 */ 693 public char charAt(int index) { 694 if ((index < 0) || (index >= count)) { 695 throw new StringIndexOutOfBoundsException(index); 696 } 697 return value[index + offset]; 698 } 699 700 /** 701 * Returns the character (Unicode code point) at the specified 702 * index. The index refers to <code>char</code> values 703 * (Unicode code units) and ranges from <code>0</code> to 704 * {@link #length()}<code> - 1</code>. 705 * 706 * <p> If the <code>char</code> value specified at the given index 707 * is in the high-surrogate range, the following index is less 708 * than the length of this <code>String</code>, and the 709 * <code>char</code> value at the following index is in the 710 * low-surrogate range, then the supplementary code point 711 * corresponding to this surrogate pair is returned. Otherwise, 712 * the <code>char</code> value at the given index is returned. 713 * 714 * @param index the index to the <code>char</code> values 715 * @return the code point value of the character at the 716 * <code>index</code> 717 * @exception IndexOutOfBoundsException if the <code>index</code> 718 * argument is negative or not less than the length of this 719 * string. 720 * @since 1.5 721 */ 722 public int codePointAt(int index) { 723 if ((index < 0) || (index >= count)) { 724 throw new StringIndexOutOfBoundsException(index); 725 } 726 return Character.codePointAtImpl(value, offset + index, offset + count); 727 } 728 729 /** 730 * Returns the character (Unicode code point) before the specified 731 * index. The index refers to <code>char</code> values 732 * (Unicode code units) and ranges from <code>1</code> to {@link 733 * CharSequence#length() length}. 734 * 735 * <p> If the <code>char</code> value at <code>(index - 1)</code> 736 * is in the low-surrogate range, <code>(index - 2)</code> is not 737 * negative, and the <code>char</code> value at <code>(index - 738 * 2)</code> is in the high-surrogate range, then the 739 * supplementary code point value of the surrogate pair is 740 * returned. If the <code>char</code> value at <code>index - 741 * 1</code> is an unpaired low-surrogate or a high-surrogate, the 742 * surrogate value is returned. 743 * 744 * @param index the index following the code point that should be returned 745 * @return the Unicode code point value before the given index. 746 * @exception IndexOutOfBoundsException if the <code>index</code> 747 * argument is less than 1 or greater than the length 748 * of this string. 749 * @since 1.5 750 */ 751 public int codePointBefore(int index) { 752 int i = index - 1; 753 if ((i < 0) || (i >= count)) { 754 throw new StringIndexOutOfBoundsException(index); 755 } 756 return Character.codePointBeforeImpl(value, offset + index, offset); 757 } 758 759 /** 760 * Returns the number of Unicode code points in the specified text 761 * range of this <code>String</code>. The text range begins at the 762 * specified <code>beginIndex</code> and extends to the 763 * <code>char</code> at index <code>endIndex - 1</code>. Thus the 764 * length (in <code>char</code>s) of the text range is 765 * <code>endIndex-beginIndex</code>. Unpaired surrogates within 766 * the text range count as one code point each. 767 * 768 * @param beginIndex the index to the first <code>char</code> of 769 * the text range. 770 * @param endIndex the index after the last <code>char</code> of 771 * the text range. 772 * @return the number of Unicode code points in the specified text 773 * range 774 * @exception IndexOutOfBoundsException if the 775 * <code>beginIndex</code> is negative, or <code>endIndex</code> 776 * is larger than the length of this <code>String</code>, or 777 * <code>beginIndex</code> is larger than <code>endIndex</code>. 778 * @since 1.5 779 */ 780 public int codePointCount(int beginIndex, int endIndex) { 781 if (beginIndex < 0 || endIndex > count || beginIndex > endIndex) { 782 throw new IndexOutOfBoundsException(); 783 } 784 return Character.codePointCountImpl(value, offset+beginIndex, endIndex-beginIndex); 785 } 786 787 /** 788 * Returns the index within this <code>String</code> that is 789 * offset from the given <code>index</code> by 790 * <code>codePointOffset</code> code points. Unpaired surrogates 791 * within the text range given by <code>index</code> and 792 * <code>codePointOffset</code> count as one code point each. 793 * 794 * @param index the index to be offset 795 * @param codePointOffset the offset in code points 796 * @return the index within this <code>String</code> 797 * @exception IndexOutOfBoundsException if <code>index</code> 798 * is negative or larger then the length of this 799 * <code>String</code>, or if <code>codePointOffset</code> is positive 800 * and the substring starting with <code>index</code> has fewer 801 * than <code>codePointOffset</code> code points, 802 * or if <code>codePointOffset</code> is negative and the substring 803 * before <code>index</code> has fewer than the absolute value 804 * of <code>codePointOffset</code> code points. 805 * @since 1.5 806 */ 807 public int offsetByCodePoints(int index, int codePointOffset) { 808 if (index < 0 || index > count) { 809 throw new IndexOutOfBoundsException(); 810 } 811 return Character.offsetByCodePointsImpl(value, offset, count, 812 offset+index, codePointOffset) - offset; 813 } 814 815 /** 816 * Copy characters from this string into dst starting at dstBegin. 817 * This method doesn't perform any range checking. 818 */ 819 void getChars(char dst[], int dstBegin) { 820 System.arraycopy(value, offset, dst, dstBegin, count); 821 } 822 823 /** 824 * Copies characters from this string into the destination character 825 * array. 826 * <p> 827 * The first character to be copied is at index <code>srcBegin</code>; 828 * the last character to be copied is at index <code>srcEnd-1</code> 829 * (thus the total number of characters to be copied is 830 * <code>srcEnd-srcBegin</code>). The characters are copied into the 831 * subarray of <code>dst</code> starting at index <code>dstBegin</code> 832 * and ending at index: 833 * <p><blockquote><pre> 834 * dstbegin + (srcEnd-srcBegin) - 1 835 * </pre></blockquote> 836 * 837 * @param srcBegin index of the first character in the string 838 * to copy. 839 * @param srcEnd index after the last character in the string 840 * to copy. 841 * @param dst the destination array. 842 * @param dstBegin the start offset in the destination array. 843 * @exception IndexOutOfBoundsException If any of the following 844 * is true: 845 * <ul><li><code>srcBegin</code> is negative. 846 * <li><code>srcBegin</code> is greater than <code>srcEnd</code> 847 * <li><code>srcEnd</code> is greater than the length of this 848 * string 849 * <li><code>dstBegin</code> is negative 850 * <li><code>dstBegin+(srcEnd-srcBegin)</code> is larger than 851 * <code>dst.length</code></ul> 852 */ 853 public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) { 854 if (srcBegin < 0) { 855 throw new StringIndexOutOfBoundsException(srcBegin); 856 } 857 if (srcEnd > count) { 858 throw new StringIndexOutOfBoundsException(srcEnd); 859 } 860 if (srcBegin > srcEnd) { 861 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin); 862 } 863 System.arraycopy(value, offset + srcBegin, dst, dstBegin, 864 srcEnd - srcBegin); 865 } 866 867 /** 868 * Copies characters from this string into the destination byte array. Each 869 * byte receives the 8 low-order bits of the corresponding character. The 870 * eight high-order bits of each character are not copied and do not 871 * participate in the transfer in any way. 1118 * 1119 * @param anotherString 1120 * The {@code String} to compare this {@code String} against 1121 * 1122 * @return {@code true} if the argument is not {@code null} and it 1123 * represents an equivalent {@code String} ignoring case; {@code 1124 * false} otherwise 1125 * 1126 * @see #equals(Object) 1127 */ 1128 public boolean equalsIgnoreCase(String anotherString) { 1129 return (this == anotherString) ? true : 1130 (anotherString != null) && (anotherString.count == count) && 1131 regionMatches(true, 0, anotherString, 0, count); 1132 } 1133 1134 /** 1135 * Compares two strings lexicographically. 1136 * The comparison is based on the Unicode value of each character in 1137 * the strings. The character sequence represented by this 1138 * <code>String</code> object is compared lexicographically to the 1139 * character sequence represented by the argument string. The result is 1140 * a negative integer if this <code>String</code> object 1141 * lexicographically precedes the argument string. The result is a 1142 * positive integer if this <code>String</code> object lexicographically 1143 * follows the argument string. The result is zero if the strings 1144 * are equal; <code>compareTo</code> returns <code>0</code> exactly when 1145 * the {@link #equals(Object)} method would return <code>true</code>. 1146 * <p> 1147 * This is the definition of lexicographic ordering. If two strings are 1148 * different, then either they have different characters at some index 1149 * that is a valid index for both strings, or their lengths are different, 1150 * or both. If they have different characters at one or more index 1151 * positions, let <i>k</i> be the smallest such index; then the string 1152 * whose character at position <i>k</i> has the smaller value, as 1153 * determined by using the < operator, lexicographically precedes the 1154 * other string. In this case, <code>compareTo</code> returns the 1155 * difference of the two character values at position <code>k</code> in 1156 * the two string -- that is, the value: 1157 * <blockquote><pre> 1158 * this.charAt(k)-anotherString.charAt(k) 1159 * </pre></blockquote> 1160 * If there is no index position at which they differ, then the shorter 1161 * string lexicographically precedes the longer string. In this case, 1162 * <code>compareTo</code> returns the difference of the lengths of the 1163 * strings -- that is, the value: 1164 * <blockquote><pre> 1165 * this.length()-anotherString.length() 1166 * </pre></blockquote> 1167 * 1168 * @param anotherString the <code>String</code> to be compared. 1169 * @return the value <code>0</code> if the argument string is equal to 1170 * this string; a value less than <code>0</code> if this string 1171 * is lexicographically less than the string argument; and a 1172 * value greater than <code>0</code> if this string is 1173 * lexicographically greater than the string argument. 1174 */ 1175 public int compareTo(String anotherString) { 1176 int len1 = count; 1177 int len2 = anotherString.count; 1178 int n = Math.min(len1, len2); 1179 char v1[] = value; 1180 char v2[] = anotherString.value; 1181 int i = offset; 1182 int j = anotherString.offset; 1183 1184 if (i == j) { 1185 int k = i; 1186 int lim = n + i; 1187 while (k < lim) { 1188 char c1 = v1[k]; 1189 char c2 = v2[k]; 1190 if (c1 != c2) { 1191 return c1 - c2; 1192 } 1193 k++; 1194 } 1195 } else { 1196 while (n-- != 0) { 1197 char c1 = v1[i++]; 1198 char c2 = v2[j++]; 1199 if (c1 != c2) { 1200 return c1 - c2; 1201 } 1202 } 1203 } 1204 return len1 - len2; 1205 } 1206 1207 /** 1208 * A Comparator that orders <code>String</code> objects as by 1209 * <code>compareToIgnoreCase</code>. This comparator is serializable. 1210 * <p> 1211 * Note that this Comparator does <em>not</em> take locale into account, 1212 * and will result in an unsatisfactory ordering for certain locales. 1213 * The java.text package provides <em>Collators</em> to allow 1214 * locale-sensitive ordering. 1215 * 1216 * @see java.text.Collator#compare(String, String) 1217 * @since 1.2 1218 */ 1219 public static final Comparator<String> CASE_INSENSITIVE_ORDER 1220 = new CaseInsensitiveComparator(); 1221 private static class CaseInsensitiveComparator 1222 implements Comparator<String>, java.io.Serializable { 1223 // use serialVersionUID from JDK 1.2.2 for interoperability 1224 private static final long serialVersionUID = 8575799808933029326L; 1225 1226 public int compare(String s1, String s2) { 1227 int n1 = s1.length(); 1228 int n2 = s2.length(); 1229 int min = Math.min(n1, n2); 1236 if (c1 != c2) { 1237 c1 = Character.toLowerCase(c1); 1238 c2 = Character.toLowerCase(c2); 1239 if (c1 != c2) { 1240 // No overflow because of numeric promotion 1241 return c1 - c2; 1242 } 1243 } 1244 } 1245 } 1246 return n1 - n2; 1247 } 1248 1249 /** Replaces the de-serialized object. */ 1250 private Object readResolve() { return CASE_INSENSITIVE_ORDER; } 1251 } 1252 1253 /** 1254 * Compares two strings lexicographically, ignoring case 1255 * differences. This method returns an integer whose sign is that of 1256 * calling <code>compareTo</code> with normalized versions of the strings 1257 * where case differences have been eliminated by calling 1258 * <code>Character.toLowerCase(Character.toUpperCase(character))</code> on 1259 * each character. 1260 * <p> 1261 * Note that this method does <em>not</em> take locale into account, 1262 * and will result in an unsatisfactory ordering for certain locales. 1263 * The java.text package provides <em>collators</em> to allow 1264 * locale-sensitive ordering. 1265 * 1266 * @param str the <code>String</code> to be compared. 1267 * @return a negative integer, zero, or a positive integer as the 1268 * specified String is greater than, equal to, or less 1269 * than this String, ignoring case considerations. 1270 * @see java.text.Collator#compare(String, String) 1271 * @since 1.2 1272 */ 1273 public int compareToIgnoreCase(String str) { 1274 return CASE_INSENSITIVE_ORDER.compare(this, str); 1275 } 1276 1277 /** 1278 * Tests if two string regions are equal. 1279 * <p> 1280 * A substring of this <tt>String</tt> object is compared to a substring 1281 * of the argument other. The result is true if these substrings 1282 * represent identical character sequences. The substring of this 1283 * <tt>String</tt> object to be compared begins at index <tt>toffset</tt> 1284 * and has length <tt>len</tt>. The substring of other to be compared 1285 * begins at index <tt>ooffset</tt> and has length <tt>len</tt>. The 1286 * result is <tt>false</tt> if and only if at least one of the following 1287 * is true: 1288 * <ul><li><tt>toffset</tt> is negative. 1289 * <li><tt>ooffset</tt> is negative. 1290 * <li><tt>toffset+len</tt> is greater than the length of this 1291 * <tt>String</tt> object. 1292 * <li><tt>ooffset+len</tt> is greater than the length of the other 1293 * argument. 1294 * <li>There is some nonnegative integer <i>k</i> less than <tt>len</tt> 1295 * such that: 1296 * <tt>this.charAt(toffset+<i>k</i>) != other.charAt(ooffset+<i>k</i>)</tt> 1297 * </ul> 1298 * 1299 * @param toffset the starting offset of the subregion in this string. 1300 * @param other the string argument. 1301 * @param ooffset the starting offset of the subregion in the string 1302 * argument. 1303 * @param len the number of characters to compare. 1304 * @return <code>true</code> if the specified subregion of this string 1305 * exactly matches the specified subregion of the string argument; 1306 * <code>false</code> otherwise. 1307 */ 1308 public boolean regionMatches(int toffset, String other, int ooffset, 1309 int len) { 1310 char ta[] = value; 1311 int to = offset + toffset; 1312 char pa[] = other.value; 1313 int po = other.offset + ooffset; 1314 // Note: toffset, ooffset, or len might be near -1>>>1. 1315 if ((ooffset < 0) || (toffset < 0) || (toffset > (long)count - len) 1316 || (ooffset > (long)other.count - len)) { 1317 return false; 1318 } 1319 while (len-- > 0) { 1320 if (ta[to++] != pa[po++]) { 1321 return false; 1322 } 1323 } 1324 return true; 1325 } 1326 1343 * <li><tt>ooffset+len</tt> is greater than the length of the other 1344 * argument. 1345 * <li><tt>ignoreCase</tt> is <tt>false</tt> and there is some nonnegative 1346 * integer <i>k</i> less than <tt>len</tt> such that: 1347 * <blockquote><pre> 1348 * this.charAt(toffset+k) != other.charAt(ooffset+k) 1349 * </pre></blockquote> 1350 * <li><tt>ignoreCase</tt> is <tt>true</tt> and there is some nonnegative 1351 * integer <i>k</i> less than <tt>len</tt> such that: 1352 * <blockquote><pre> 1353 * Character.toLowerCase(this.charAt(toffset+k)) != 1354 Character.toLowerCase(other.charAt(ooffset+k)) 1355 * </pre></blockquote> 1356 * and: 1357 * <blockquote><pre> 1358 * Character.toUpperCase(this.charAt(toffset+k)) != 1359 * Character.toUpperCase(other.charAt(ooffset+k)) 1360 * </pre></blockquote> 1361 * </ul> 1362 * 1363 * @param ignoreCase if <code>true</code>, ignore case when comparing 1364 * characters. 1365 * @param toffset the starting offset of the subregion in this 1366 * string. 1367 * @param other the string argument. 1368 * @param ooffset the starting offset of the subregion in the string 1369 * argument. 1370 * @param len the number of characters to compare. 1371 * @return <code>true</code> if the specified subregion of this string 1372 * matches the specified subregion of the string argument; 1373 * <code>false</code> otherwise. Whether the matching is exact 1374 * or case insensitive depends on the <code>ignoreCase</code> 1375 * argument. 1376 */ 1377 public boolean regionMatches(boolean ignoreCase, int toffset, 1378 String other, int ooffset, int len) { 1379 char ta[] = value; 1380 int to = offset + toffset; 1381 char pa[] = other.value; 1382 int po = other.offset + ooffset; 1383 // Note: toffset, ooffset, or len might be near -1>>>1. 1384 if ((ooffset < 0) || (toffset < 0) || (toffset > (long)count - len) || 1385 (ooffset > (long)other.count - len)) { 1386 return false; 1387 } 1388 while (len-- > 0) { 1389 char c1 = ta[to++]; 1390 char c2 = pa[po++]; 1391 if (c1 == c2) { 1392 continue; 1393 } 1394 if (ignoreCase) { 1403 } 1404 // Unfortunately, conversion to uppercase does not work properly 1405 // for the Georgian alphabet, which has strange rules about case 1406 // conversion. So we need to make one last check before 1407 // exiting. 1408 if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) { 1409 continue; 1410 } 1411 } 1412 return false; 1413 } 1414 return true; 1415 } 1416 1417 /** 1418 * Tests if the substring of this string beginning at the 1419 * specified index starts with the specified prefix. 1420 * 1421 * @param prefix the prefix. 1422 * @param toffset where to begin looking in this string. 1423 * @return <code>true</code> if the character sequence represented by the 1424 * argument is a prefix of the substring of this object starting 1425 * at index <code>toffset</code>; <code>false</code> otherwise. 1426 * The result is <code>false</code> if <code>toffset</code> is 1427 * negative or greater than the length of this 1428 * <code>String</code> object; otherwise the result is the same 1429 * as the result of the expression 1430 * <pre> 1431 * this.substring(toffset).startsWith(prefix) 1432 * </pre> 1433 */ 1434 public boolean startsWith(String prefix, int toffset) { 1435 char ta[] = value; 1436 int to = offset + toffset; 1437 char pa[] = prefix.value; 1438 int po = prefix.offset; 1439 int pc = prefix.count; 1440 // Note: toffset might be near -1>>>1. 1441 if ((toffset < 0) || (toffset > count - pc)) { 1442 return false; 1443 } 1444 while (--pc >= 0) { 1445 if (ta[to++] != pa[po++]) { 1446 return false; 1447 } 1448 } 1449 return true; 1450 } 1451 1452 /** 1453 * Tests if this string starts with the specified prefix. 1454 * 1455 * @param prefix the prefix. 1456 * @return <code>true</code> if the character sequence represented by the 1457 * argument is a prefix of the character sequence represented by 1458 * this string; <code>false</code> otherwise. 1459 * Note also that <code>true</code> will be returned if the 1460 * argument is an empty string or is equal to this 1461 * <code>String</code> object as determined by the 1462 * {@link #equals(Object)} method. 1463 * @since 1. 0 1464 */ 1465 public boolean startsWith(String prefix) { 1466 return startsWith(prefix, 0); 1467 } 1468 1469 /** 1470 * Tests if this string ends with the specified suffix. 1471 * 1472 * @param suffix the suffix. 1473 * @return <code>true</code> if the character sequence represented by the 1474 * argument is a suffix of the character sequence represented by 1475 * this object; <code>false</code> otherwise. Note that the 1476 * result will be <code>true</code> if the argument is the 1477 * empty string or is equal to this <code>String</code> object 1478 * as determined by the {@link #equals(Object)} method. 1479 */ 1480 public boolean endsWith(String suffix) { 1481 return startsWith(suffix, count - suffix.count); 1482 } 1483 1484 /** 1485 * Returns a hash code for this string. The hash code for a 1486 * <code>String</code> object is computed as 1487 * <blockquote><pre> 1488 * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1] 1489 * </pre></blockquote> 1490 * using <code>int</code> arithmetic, where <code>s[i]</code> is the 1491 * <i>i</i>th character of the string, <code>n</code> is the length of 1492 * the string, and <code>^</code> indicates exponentiation. 1493 * (The hash value of the empty string is zero.) 1494 * 1495 * @return a hash code value for this object. 1496 */ 1497 public int hashCode() { 1498 int h = hash; 1499 if (h == 0 && count > 0) { 1500 int off = offset; 1501 char val[] = value; 1502 int len = count; 1503 1504 for (int i = 0; i < len; i++) { 1505 h = 31*h + val[off++]; 1506 } 1507 hash = h; 1508 } 1509 return h; 1510 } 1511 1512 /** 1513 * Returns the index within this string of the first occurrence of 1514 * the specified character. If a character with value 1515 * <code>ch</code> occurs in the character sequence represented by 1516 * this <code>String</code> object, then the index (in Unicode 1517 * code units) of the first such occurrence is returned. For 1518 * values of <code>ch</code> in the range from 0 to 0xFFFF 1519 * (inclusive), this is the smallest value <i>k</i> such that: 1520 * <blockquote><pre> 1521 * this.charAt(<i>k</i>) == ch 1522 * </pre></blockquote> 1523 * is true. For other values of <code>ch</code>, it is the 1524 * smallest value <i>k</i> such that: 1525 * <blockquote><pre> 1526 * this.codePointAt(<i>k</i>) == ch 1527 * </pre></blockquote> 1528 * is true. In either case, if no such character occurs in this 1529 * string, then <code>-1</code> is returned. 1530 * 1531 * @param ch a character (Unicode code point). 1532 * @return the index of the first occurrence of the character in the 1533 * character sequence represented by this object, or 1534 * <code>-1</code> if the character does not occur. 1535 */ 1536 public int indexOf(int ch) { 1537 return indexOf(ch, 0); 1538 } 1539 1540 /** 1541 * Returns the index within this string of the first occurrence of the 1542 * specified character, starting the search at the specified index. 1543 * <p> 1544 * If a character with value <code>ch</code> occurs in the 1545 * character sequence represented by this <code>String</code> 1546 * object at an index no smaller than <code>fromIndex</code>, then 1547 * the index of the first such occurrence is returned. For values 1548 * of <code>ch</code> in the range from 0 to 0xFFFF (inclusive), 1549 * this is the smallest value <i>k</i> such that: 1550 * <blockquote><pre> 1551 * (this.charAt(<i>k</i>) == ch) && (<i>k</i> >= fromIndex) 1552 * </pre></blockquote> 1553 * is true. For other values of <code>ch</code>, it is the 1554 * smallest value <i>k</i> such that: 1555 * <blockquote><pre> 1556 * (this.codePointAt(<i>k</i>) == ch) && (<i>k</i> >= fromIndex) 1557 * </pre></blockquote> 1558 * is true. In either case, if no such character occurs in this 1559 * string at or after position <code>fromIndex</code>, then 1560 * <code>-1</code> is returned. 1561 * 1562 * <p> 1563 * There is no restriction on the value of <code>fromIndex</code>. If it 1564 * is negative, it has the same effect as if it were zero: this entire 1565 * string may be searched. If it is greater than the length of this 1566 * string, it has the same effect as if it were equal to the length of 1567 * this string: <code>-1</code> is returned. 1568 * 1569 * <p>All indices are specified in <code>char</code> values 1570 * (Unicode code units). 1571 * 1572 * @param ch a character (Unicode code point). 1573 * @param fromIndex the index to start the search from. 1574 * @return the index of the first occurrence of the character in the 1575 * character sequence represented by this object that is greater 1576 * than or equal to <code>fromIndex</code>, or <code>-1</code> 1577 * if the character does not occur. 1578 */ 1579 public int indexOf(int ch, int fromIndex) { 1580 if (fromIndex < 0) { 1581 fromIndex = 0; 1582 } else if (fromIndex >= count) { 1583 // Note: fromIndex might be near -1>>>1. 1584 return -1; 1585 } 1586 1587 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) { 1588 // handle most cases here (ch is a BMP code point or a 1589 // negative value (invalid code point)) 1590 final char[] value = this.value; 1591 final int offset = this.offset; 1592 final int max = offset + count; 1593 for (int i = offset + fromIndex; i < max ; i++) { 1594 if (value[i] == ch) { 1595 return i - offset; 1596 } 1605 * Handles (rare) calls of indexOf with a supplementary character. 1606 */ 1607 private int indexOfSupplementary(int ch, int fromIndex) { 1608 if (Character.isValidCodePoint(ch)) { 1609 final char[] value = this.value; 1610 final int offset = this.offset; 1611 final char hi = Character.highSurrogate(ch); 1612 final char lo = Character.lowSurrogate(ch); 1613 final int max = offset + count - 1; 1614 for (int i = offset + fromIndex; i < max; i++) { 1615 if (value[i] == hi && value[i+1] == lo) { 1616 return i - offset; 1617 } 1618 } 1619 } 1620 return -1; 1621 } 1622 1623 /** 1624 * Returns the index within this string of the last occurrence of 1625 * the specified character. For values of <code>ch</code> in the 1626 * range from 0 to 0xFFFF (inclusive), the index (in Unicode code 1627 * units) returned is the largest value <i>k</i> such that: 1628 * <blockquote><pre> 1629 * this.charAt(<i>k</i>) == ch 1630 * </pre></blockquote> 1631 * is true. For other values of <code>ch</code>, it is the 1632 * largest value <i>k</i> such that: 1633 * <blockquote><pre> 1634 * this.codePointAt(<i>k</i>) == ch 1635 * </pre></blockquote> 1636 * is true. In either case, if no such character occurs in this 1637 * string, then <code>-1</code> is returned. The 1638 * <code>String</code> is searched backwards starting at the last 1639 * character. 1640 * 1641 * @param ch a character (Unicode code point). 1642 * @return the index of the last occurrence of the character in the 1643 * character sequence represented by this object, or 1644 * <code>-1</code> if the character does not occur. 1645 */ 1646 public int lastIndexOf(int ch) { 1647 return lastIndexOf(ch, count - 1); 1648 } 1649 1650 /** 1651 * Returns the index within this string of the last occurrence of 1652 * the specified character, searching backward starting at the 1653 * specified index. For values of <code>ch</code> in the range 1654 * from 0 to 0xFFFF (inclusive), the index returned is the largest 1655 * value <i>k</i> such that: 1656 * <blockquote><pre> 1657 * (this.charAt(<i>k</i>) == ch) && (<i>k</i> <= fromIndex) 1658 * </pre></blockquote> 1659 * is true. For other values of <code>ch</code>, it is the 1660 * largest value <i>k</i> such that: 1661 * <blockquote><pre> 1662 * (this.codePointAt(<i>k</i>) == ch) && (<i>k</i> <= fromIndex) 1663 * </pre></blockquote> 1664 * is true. In either case, if no such character occurs in this 1665 * string at or before position <code>fromIndex</code>, then 1666 * <code>-1</code> is returned. 1667 * 1668 * <p>All indices are specified in <code>char</code> values 1669 * (Unicode code units). 1670 * 1671 * @param ch a character (Unicode code point). 1672 * @param fromIndex the index to start the search from. There is no 1673 * restriction on the value of <code>fromIndex</code>. If it is 1674 * greater than or equal to the length of this string, it has 1675 * the same effect as if it were equal to one less than the 1676 * length of this string: this entire string may be searched. 1677 * If it is negative, it has the same effect as if it were -1: 1678 * -1 is returned. 1679 * @return the index of the last occurrence of the character in the 1680 * character sequence represented by this object that is less 1681 * than or equal to <code>fromIndex</code>, or <code>-1</code> 1682 * if the character does not occur before that point. 1683 */ 1684 public int lastIndexOf(int ch, int fromIndex) { 1685 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) { 1686 // handle most cases here (ch is a BMP code point or a 1687 // negative value (invalid code point)) 1688 final char[] value = this.value; 1689 final int offset = this.offset; 1690 int i = offset + Math.min(fromIndex, count - 1); 1691 for (; i >= offset ; i--) { 1692 if (value[i] == ch) { 1693 return i - offset; 1694 } 1695 } 1696 return -1; 1697 } else { 1698 return lastIndexOfSupplementary(ch, fromIndex); 1699 } 1700 } 1701 1904 } 1905 } 1906 return start - sourceOffset + 1; 1907 } 1908 } 1909 1910 /** 1911 * Returns a new string that is a substring of this string. The 1912 * substring begins with the character at the specified index and 1913 * extends to the end of this string. <p> 1914 * Examples: 1915 * <blockquote><pre> 1916 * "unhappy".substring(2) returns "happy" 1917 * "Harbison".substring(3) returns "bison" 1918 * "emptiness".substring(9) returns "" (an empty string) 1919 * </pre></blockquote> 1920 * 1921 * @param beginIndex the beginning index, inclusive. 1922 * @return the specified substring. 1923 * @exception IndexOutOfBoundsException if 1924 * <code>beginIndex</code> is negative or larger than the 1925 * length of this <code>String</code> object. 1926 */ 1927 public String substring(int beginIndex) { 1928 return substring(beginIndex, count); 1929 } 1930 1931 /** 1932 * Returns a new string that is a substring of this string. The 1933 * substring begins at the specified <code>beginIndex</code> and 1934 * extends to the character at index <code>endIndex - 1</code>. 1935 * Thus the length of the substring is <code>endIndex-beginIndex</code>. 1936 * <p> 1937 * Examples: 1938 * <blockquote><pre> 1939 * "hamburger".substring(4, 8) returns "urge" 1940 * "smiles".substring(1, 5) returns "mile" 1941 * </pre></blockquote> 1942 * 1943 * @param beginIndex the beginning index, inclusive. 1944 * @param endIndex the ending index, exclusive. 1945 * @return the specified substring. 1946 * @exception IndexOutOfBoundsException if the 1947 * <code>beginIndex</code> is negative, or 1948 * <code>endIndex</code> is larger than the length of 1949 * this <code>String</code> object, or 1950 * <code>beginIndex</code> is larger than 1951 * <code>endIndex</code>. 1952 */ 1953 public String substring(int beginIndex, int endIndex) { 1954 if (beginIndex < 0) { 1955 throw new StringIndexOutOfBoundsException(beginIndex); 1956 } 1957 if (endIndex > count) { 1958 throw new StringIndexOutOfBoundsException(endIndex); 1959 } 1960 if (beginIndex > endIndex) { 1961 throw new StringIndexOutOfBoundsException(endIndex - beginIndex); 1962 } 1963 return ((beginIndex == 0) && (endIndex == count)) ? this : 1964 new String(offset + beginIndex, endIndex - beginIndex, value); 1965 } 1966 1967 /** 1968 * Returns a new character sequence that is a subsequence of this sequence. 1969 * 1970 * <p> An invocation of this method of the form 1971 * 1982 * 1983 * @param beginIndex the begin index, inclusive. 1984 * @param endIndex the end index, exclusive. 1985 * @return the specified subsequence. 1986 * 1987 * @throws IndexOutOfBoundsException 1988 * if <tt>beginIndex</tt> or <tt>endIndex</tt> are negative, 1989 * if <tt>endIndex</tt> is greater than <tt>length()</tt>, 1990 * or if <tt>beginIndex</tt> is greater than <tt>startIndex</tt> 1991 * 1992 * @since 1.4 1993 * @spec JSR-51 1994 */ 1995 public CharSequence subSequence(int beginIndex, int endIndex) { 1996 return this.substring(beginIndex, endIndex); 1997 } 1998 1999 /** 2000 * Concatenates the specified string to the end of this string. 2001 * <p> 2002 * If the length of the argument string is <code>0</code>, then this 2003 * <code>String</code> object is returned. Otherwise, a new 2004 * <code>String</code> object is created, representing a character 2005 * sequence that is the concatenation of the character sequence 2006 * represented by this <code>String</code> object and the character 2007 * sequence represented by the argument string.<p> 2008 * Examples: 2009 * <blockquote><pre> 2010 * "cares".concat("s") returns "caress" 2011 * "to".concat("get").concat("her") returns "together" 2012 * </pre></blockquote> 2013 * 2014 * @param str the <code>String</code> that is concatenated to the end 2015 * of this <code>String</code>. 2016 * @return a string that represents the concatenation of this object's 2017 * characters followed by the string argument's characters. 2018 */ 2019 public String concat(String str) { 2020 int otherLen = str.length(); 2021 if (otherLen == 0) { 2022 return this; 2023 } 2024 char buf[] = new char[count + otherLen]; 2025 getChars(0, count, buf, 0); 2026 str.getChars(0, otherLen, buf, count); 2027 return new String(0, count + otherLen, buf); 2028 } 2029 2030 /** 2031 * Returns a new string resulting from replacing all occurrences of 2032 * <code>oldChar</code> in this string with <code>newChar</code>. 2033 * <p> 2034 * If the character <code>oldChar</code> does not occur in the 2035 * character sequence represented by this <code>String</code> object, 2036 * then a reference to this <code>String</code> object is returned. 2037 * Otherwise, a new <code>String</code> object is created that 2038 * represents a character sequence identical to the character sequence 2039 * represented by this <code>String</code> object, except that every 2040 * occurrence of <code>oldChar</code> is replaced by an occurrence 2041 * of <code>newChar</code>. 2042 * <p> 2043 * Examples: 2044 * <blockquote><pre> 2045 * "mesquite in your cellar".replace('e', 'o') 2046 * returns "mosquito in your collar" 2047 * "the war of baronets".replace('r', 'y') 2048 * returns "the way of bayonets" 2049 * "sparring with a purple porpoise".replace('p', 't') 2050 * returns "starring with a turtle tortoise" 2051 * "JonL".replace('q', 'x') returns "JonL" (no change) 2052 * </pre></blockquote> 2053 * 2054 * @param oldChar the old character. 2055 * @param newChar the new character. 2056 * @return a string derived from this string by replacing every 2057 * occurrence of <code>oldChar</code> with <code>newChar</code>. 2058 */ 2059 public String replace(char oldChar, char newChar) { 2060 if (oldChar != newChar) { 2061 int len = count; 2062 int i = -1; 2063 char[] val = value; /* avoid getfield opcode */ 2064 int off = offset; /* avoid getfield opcode */ 2065 2066 while (++i < len) { 2067 if (val[off + i] == oldChar) { 2068 break; 2069 } 2070 } 2071 if (i < len) { 2072 char buf[] = new char[len]; 2073 for (int j = 0 ; j < i ; j++) { 2074 buf[j] = val[off+j]; 2075 } 2076 while (i < len) { 2077 char c = val[off + i]; 2102 * @return <tt>true</tt> if, and only if, this string matches the 2103 * given regular expression 2104 * 2105 * @throws PatternSyntaxException 2106 * if the regular expression's syntax is invalid 2107 * 2108 * @see java.util.regex.Pattern 2109 * 2110 * @since 1.4 2111 * @spec JSR-51 2112 */ 2113 public boolean matches(String regex) { 2114 return Pattern.matches(regex, this); 2115 } 2116 2117 /** 2118 * Returns true if and only if this string contains the specified 2119 * sequence of char values. 2120 * 2121 * @param s the sequence to search for 2122 * @return true if this string contains <code>s</code>, false otherwise 2123 * @throws NullPointerException if <code>s</code> is <code>null</code> 2124 * @since 1.5 2125 */ 2126 public boolean contains(CharSequence s) { 2127 return indexOf(s.toString()) > -1; 2128 } 2129 2130 /** 2131 * Replaces the first substring of this string that matches the given <a 2132 * href="../util/regex/Pattern.html#sum">regular expression</a> with the 2133 * given replacement. 2134 * 2135 * <p> An invocation of this method of the form 2136 * <i>str</i><tt>.replaceFirst(</tt><i>regex</i><tt>,</tt> <i>repl</i><tt>)</tt> 2137 * yields exactly the same result as the expression 2138 * 2139 * <blockquote><tt> 2140 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile 2141 * compile}(</tt><i>regex</i><tt>).{@link 2142 * java.util.regex.Pattern#matcher(java.lang.CharSequence) 2143 * matcher}(</tt><i>str</i><tt>).{@link java.util.regex.Matcher#replaceFirst 2206 * 2207 * @see java.util.regex.Pattern 2208 * 2209 * @since 1.4 2210 * @spec JSR-51 2211 */ 2212 public String replaceAll(String regex, String replacement) { 2213 return Pattern.compile(regex).matcher(this).replaceAll(replacement); 2214 } 2215 2216 /** 2217 * Replaces each substring of this string that matches the literal target 2218 * sequence with the specified literal replacement sequence. The 2219 * replacement proceeds from the beginning of the string to the end, for 2220 * example, replacing "aa" with "b" in the string "aaa" will result in 2221 * "ba" rather than "ab". 2222 * 2223 * @param target The sequence of char values to be replaced 2224 * @param replacement The replacement sequence of char values 2225 * @return The resulting string 2226 * @throws NullPointerException if <code>target</code> or 2227 * <code>replacement</code> is <code>null</code>. 2228 * @since 1.5 2229 */ 2230 public String replace(CharSequence target, CharSequence replacement) { 2231 return Pattern.compile(target.toString(), Pattern.LITERAL).matcher( 2232 this).replaceAll(Matcher.quoteReplacement(replacement.toString())); 2233 } 2234 2235 /** 2236 * Splits this string around matches of the given 2237 * <a href="../util/regex/Pattern.html#sum">regular expression</a>. 2238 * 2239 * <p> The array returned by this method contains each substring of this 2240 * string that is terminated by another substring that matches the given 2241 * expression or is terminated by the end of the string. The substrings in 2242 * the array are in the order in which they occur in this string. If the 2243 * expression does not match any part of the input then the resulting array 2244 * has just one element, namely this string. 2245 * 2246 * <p> The <tt>limit</tt> parameter controls the number of times the 2247 * pattern is applied and therefore affects the length of the resulting 2390 * 2391 * @param regex 2392 * the delimiting regular expression 2393 * 2394 * @return the array of strings computed by splitting this string 2395 * around matches of the given regular expression 2396 * 2397 * @throws PatternSyntaxException 2398 * if the regular expression's syntax is invalid 2399 * 2400 * @see java.util.regex.Pattern 2401 * 2402 * @since 1.4 2403 * @spec JSR-51 2404 */ 2405 public String[] split(String regex) { 2406 return split(regex, 0); 2407 } 2408 2409 /** 2410 * Converts all of the characters in this <code>String</code> to lower 2411 * case using the rules of the given <code>Locale</code>. Case mapping is based 2412 * on the Unicode Standard version specified by the {@link java.lang.Character Character} 2413 * class. Since case mappings are not always 1:1 char mappings, the resulting 2414 * <code>String</code> may be a different length than the original <code>String</code>. 2415 * <p> 2416 * Examples of lowercase mappings are in the following table: 2417 * <table border="1" summary="Lowercase mapping examples showing language code of locale, upper case, lower case, and description"> 2418 * <tr> 2419 * <th>Language Code of Locale</th> 2420 * <th>Upper Case</th> 2421 * <th>Lower Case</th> 2422 * <th>Description</th> 2423 * </tr> 2424 * <tr> 2425 * <td>tr (Turkish)</td> 2426 * <td>\u0130</td> 2427 * <td>\u0069</td> 2428 * <td>capital letter I with dot above -> small letter i</td> 2429 * </tr> 2430 * <tr> 2431 * <td>tr (Turkish)</td> 2432 * <td>\u0049</td> 2433 * <td>\u0131</td> 2434 * <td>capital letter I -> small letter dotless i </td> 2435 * </tr> 2436 * <tr> 2437 * <td>(all)</td> 2438 * <td>French Fries</td> 2439 * <td>french fries</td> 2440 * <td>lowercased all chars in String</td> 2441 * </tr> 2442 * <tr> 2443 * <td>(all)</td> 2444 * <td><img src="doc-files/capiota.gif" alt="capiota"><img src="doc-files/capchi.gif" alt="capchi"> 2445 * <img src="doc-files/captheta.gif" alt="captheta"><img src="doc-files/capupsil.gif" alt="capupsil"> 2446 * <img src="doc-files/capsigma.gif" alt="capsigma"></td> 2447 * <td><img src="doc-files/iota.gif" alt="iota"><img src="doc-files/chi.gif" alt="chi"> 2448 * <img src="doc-files/theta.gif" alt="theta"><img src="doc-files/upsilon.gif" alt="upsilon"> 2449 * <img src="doc-files/sigma1.gif" alt="sigma"></td> 2450 * <td>lowercased all chars in String</td> 2451 * </tr> 2452 * </table> 2453 * 2454 * @param locale use the case transformation rules for this locale 2455 * @return the <code>String</code>, converted to lowercase. 2456 * @see java.lang.String#toLowerCase() 2457 * @see java.lang.String#toUpperCase() 2458 * @see java.lang.String#toUpperCase(Locale) 2459 * @since 1.1 2460 */ 2461 public String toLowerCase(Locale locale) { 2462 if (locale == null) { 2463 throw new NullPointerException(); 2464 } 2465 2466 int firstUpper; 2467 2468 /* Now check if there are any characters that need to be changed. */ 2469 scan: { 2470 for (firstUpper = 0 ; firstUpper < count; ) { 2471 char c = value[offset+firstUpper]; 2472 if ((c >= Character.MIN_HIGH_SURROGATE) && 2473 (c <= Character.MAX_HIGH_SURROGATE)) { 2474 int supplChar = codePointAt(firstUpper); 2475 if (supplChar != Character.toLowerCase(supplChar)) { 2536 /* Grow result if needed */ 2537 int mapLen = lowerCharArray.length; 2538 if (mapLen > srcCount) { 2539 char[] result2 = new char[result.length + mapLen - srcCount]; 2540 System.arraycopy(result, 0, result2, 0, 2541 i + resultOffset); 2542 result = result2; 2543 } 2544 for (int x=0; x<mapLen; ++x) { 2545 result[i+resultOffset+x] = lowerCharArray[x]; 2546 } 2547 resultOffset += (mapLen - srcCount); 2548 } else { 2549 result[i+resultOffset] = (char)lowerChar; 2550 } 2551 } 2552 return new String(0, count+resultOffset, result); 2553 } 2554 2555 /** 2556 * Converts all of the characters in this <code>String</code> to lower 2557 * case using the rules of the default locale. This is equivalent to calling 2558 * <code>toLowerCase(Locale.getDefault())</code>. 2559 * <p> 2560 * <b>Note:</b> This method is locale sensitive, and may produce unexpected 2561 * results if used for strings that are intended to be interpreted locale 2562 * independently. 2563 * Examples are programming language identifiers, protocol keys, and HTML 2564 * tags. 2565 * For instance, <code>"TITLE".toLowerCase()</code> in a Turkish locale 2566 * returns <code>"t\u005Cu0131tle"</code>, where '\u005Cu0131' is the 2567 * LATIN SMALL LETTER DOTLESS I character. 2568 * To obtain correct results for locale insensitive strings, use 2569 * <code>toLowerCase(Locale.ENGLISH)</code>. 2570 * <p> 2571 * @return the <code>String</code>, converted to lowercase. 2572 * @see java.lang.String#toLowerCase(Locale) 2573 */ 2574 public String toLowerCase() { 2575 return toLowerCase(Locale.getDefault()); 2576 } 2577 2578 /** 2579 * Converts all of the characters in this <code>String</code> to upper 2580 * case using the rules of the given <code>Locale</code>. Case mapping is based 2581 * on the Unicode Standard version specified by the {@link java.lang.Character Character} 2582 * class. Since case mappings are not always 1:1 char mappings, the resulting 2583 * <code>String</code> may be a different length than the original <code>String</code>. 2584 * <p> 2585 * Examples of locale-sensitive and 1:M case mappings are in the following table. 2586 * <p> 2587 * <table border="1" summary="Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description."> 2588 * <tr> 2589 * <th>Language Code of Locale</th> 2590 * <th>Lower Case</th> 2591 * <th>Upper Case</th> 2592 * <th>Description</th> 2593 * </tr> 2594 * <tr> 2595 * <td>tr (Turkish)</td> 2596 * <td>\u0069</td> 2597 * <td>\u0130</td> 2598 * <td>small letter i -> capital letter I with dot above</td> 2599 * </tr> 2600 * <tr> 2601 * <td>tr (Turkish)</td> 2602 * <td>\u0131</td> 2603 * <td>\u0049</td> 2604 * <td>small letter dotless i -> capital letter I</td> 2605 * </tr> 2606 * <tr> 2607 * <td>(all)</td> 2608 * <td>\u00df</td> 2609 * <td>\u0053 \u0053</td> 2610 * <td>small letter sharp s -> two letters: SS</td> 2611 * </tr> 2612 * <tr> 2613 * <td>(all)</td> 2614 * <td>Fahrvergnügen</td> 2615 * <td>FAHRVERGNÜGEN</td> 2616 * <td></td> 2617 * </tr> 2618 * </table> 2619 * @param locale use the case transformation rules for this locale 2620 * @return the <code>String</code>, converted to uppercase. 2621 * @see java.lang.String#toUpperCase() 2622 * @see java.lang.String#toLowerCase() 2623 * @see java.lang.String#toLowerCase(Locale) 2624 * @since 1.1 2625 */ 2626 public String toUpperCase(Locale locale) { 2627 if (locale == null) { 2628 throw new NullPointerException(); 2629 } 2630 2631 int firstLower; 2632 2633 /* Now check if there are any characters that need to be changed. */ 2634 scan: { 2635 for (firstLower = 0 ; firstLower < count; ) { 2636 int c = (int)value[offset+firstLower]; 2637 int srcCount; 2638 if ((c >= Character.MIN_HIGH_SURROGATE) && 2639 (c <= Character.MAX_HIGH_SURROGATE)) { 2640 c = codePointAt(firstLower); 2699 /* Grow result if needed */ 2700 int mapLen = upperCharArray.length; 2701 if (mapLen > srcCount) { 2702 char[] result2 = new char[result.length + mapLen - srcCount]; 2703 System.arraycopy(result, 0, result2, 0, 2704 i + resultOffset); 2705 result = result2; 2706 } 2707 for (int x=0; x<mapLen; ++x) { 2708 result[i+resultOffset+x] = upperCharArray[x]; 2709 } 2710 resultOffset += (mapLen - srcCount); 2711 } else { 2712 result[i+resultOffset] = (char)upperChar; 2713 } 2714 } 2715 return new String(0, count+resultOffset, result); 2716 } 2717 2718 /** 2719 * Converts all of the characters in this <code>String</code> to upper 2720 * case using the rules of the default locale. This method is equivalent to 2721 * <code>toUpperCase(Locale.getDefault())</code>. 2722 * <p> 2723 * <b>Note:</b> This method is locale sensitive, and may produce unexpected 2724 * results if used for strings that are intended to be interpreted locale 2725 * independently. 2726 * Examples are programming language identifiers, protocol keys, and HTML 2727 * tags. 2728 * For instance, <code>"title".toUpperCase()</code> in a Turkish locale 2729 * returns <code>"T\u005Cu0130TLE"</code>, where '\u005Cu0130' is the 2730 * LATIN CAPITAL LETTER I WITH DOT ABOVE character. 2731 * To obtain correct results for locale insensitive strings, use 2732 * <code>toUpperCase(Locale.ENGLISH)</code>. 2733 * <p> 2734 * @return the <code>String</code>, converted to uppercase. 2735 * @see java.lang.String#toUpperCase(Locale) 2736 */ 2737 public String toUpperCase() { 2738 return toUpperCase(Locale.getDefault()); 2739 } 2740 2741 /** 2742 * Returns a copy of the string, with leading and trailing whitespace 2743 * omitted. 2744 * <p> 2745 * If this <code>String</code> object represents an empty character 2746 * sequence, or the first and last characters of character sequence 2747 * represented by this <code>String</code> object both have codes 2748 * greater than <code>'\u0020'</code> (the space character), then a 2749 * reference to this <code>String</code> object is returned. 2750 * <p> 2751 * Otherwise, if there is no character with a code greater than 2752 * <code>'\u0020'</code> in the string, then a new 2753 * <code>String</code> object representing an empty string is created 2754 * and returned. 2755 * <p> 2756 * Otherwise, let <i>k</i> be the index of the first character in the 2757 * string whose code is greater than <code>'\u0020'</code>, and let 2758 * <i>m</i> be the index of the last character in the string whose code 2759 * is greater than <code>'\u0020'</code>. A new <code>String</code> 2760 * object is created, representing the substring of this string that 2761 * begins with the character at index <i>k</i> and ends with the 2762 * character at index <i>m</i>-that is, the result of 2763 * <code>this.substring(<i>k</i>, <i>m</i>+1)</code>. 2764 * <p> 2765 * This method may be used to trim whitespace (as defined above) from 2766 * the beginning and end of a string. 2767 * 2768 * @return A copy of this string with leading and trailing white 2769 * space removed, or this string if it has no leading or 2770 * trailing white space. 2771 */ 2772 public String trim() { 2773 int len = count; 2774 int st = 0; 2775 int off = offset; /* avoid getfield opcode */ 2776 char[] val = value; /* avoid getfield opcode */ 2777 2778 while ((st < len) && (val[off + st] <= ' ')) { 2779 st++; 2876 * specifier that is incompatible with the given arguments, 2877 * insufficient arguments given the format string, or other 2878 * illegal conditions. For specification of all possible 2879 * formatting errors, see the <a 2880 * href="../util/Formatter.html#detail">Details</a> section of the 2881 * formatter class specification 2882 * 2883 * @throws NullPointerException 2884 * If the <tt>format</tt> is <tt>null</tt> 2885 * 2886 * @return A formatted string 2887 * 2888 * @see java.util.Formatter 2889 * @since 1.5 2890 */ 2891 public static String format(Locale l, String format, Object ... args) { 2892 return new Formatter(l).format(format, args).toString(); 2893 } 2894 2895 /** 2896 * Returns the string representation of the <code>Object</code> argument. 2897 * 2898 * @param obj an <code>Object</code>. 2899 * @return if the argument is <code>null</code>, then a string equal to 2900 * <code>"null"</code>; otherwise, the value of 2901 * <code>obj.toString()</code> is returned. 2902 * @see java.lang.Object#toString() 2903 */ 2904 public static String valueOf(Object obj) { 2905 return (obj == null) ? "null" : obj.toString(); 2906 } 2907 2908 /** 2909 * Returns the string representation of the <code>char</code> array 2910 * argument. The contents of the character array are copied; subsequent 2911 * modification of the character array does not affect the newly 2912 * created string. 2913 * 2914 * @param data a <code>char</code> array. 2915 * @return a newly allocated string representing the same sequence of 2916 * characters contained in the character array argument. 2917 */ 2918 public static String valueOf(char data[]) { 2919 return new String(data); 2920 } 2921 2922 /** 2923 * Returns the string representation of a specific subarray of the 2924 * <code>char</code> array argument. 2925 * <p> 2926 * The <code>offset</code> argument is the index of the first 2927 * character of the subarray. The <code>count</code> argument 2928 * specifies the length of the subarray. The contents of the subarray 2929 * are copied; subsequent modification of the character array does not 2930 * affect the newly created string. 2931 * 2932 * @param data the character array. 2933 * @param offset the initial offset into the value of the 2934 * <code>String</code>. 2935 * @param count the length of the value of the <code>String</code>. 2936 * @return a string representing the sequence of characters contained 2937 * in the subarray of the character array argument. 2938 * @exception IndexOutOfBoundsException if <code>offset</code> is 2939 * negative, or <code>count</code> is negative, or 2940 * <code>offset+count</code> is larger than 2941 * <code>data.length</code>. 2942 */ 2943 public static String valueOf(char data[], int offset, int count) { 2944 return new String(data, offset, count); 2945 } 2946 2947 /** 2948 * Returns a String that represents the character sequence in the 2949 * array specified. 2950 * 2951 * @param data the character array. 2952 * @param offset initial offset of the subarray. 2953 * @param count length of the subarray. 2954 * @return a <code>String</code> that contains the characters of the 2955 * specified subarray of the character array. 2956 */ 2957 public static String copyValueOf(char data[], int offset, int count) { 2958 // All public String constructors now copy the data. 2959 return new String(data, offset, count); 2960 } 2961 2962 /** 2963 * Returns a String that represents the character sequence in the 2964 * array specified. 2965 * 2966 * @param data the character array. 2967 * @return a <code>String</code> that contains the characters of the 2968 * character array. 2969 */ 2970 public static String copyValueOf(char data[]) { 2971 return copyValueOf(data, 0, data.length); 2972 } 2973 2974 /** 2975 * Returns the string representation of the <code>boolean</code> argument. 2976 * 2977 * @param b a <code>boolean</code>. 2978 * @return if the argument is <code>true</code>, a string equal to 2979 * <code>"true"</code> is returned; otherwise, a string equal to 2980 * <code>"false"</code> is returned. 2981 */ 2982 public static String valueOf(boolean b) { 2983 return b ? "true" : "false"; 2984 } 2985 2986 /** 2987 * Returns the string representation of the <code>char</code> 2988 * argument. 2989 * 2990 * @param c a <code>char</code>. 2991 * @return a string of length <code>1</code> containing 2992 * as its single character the argument <code>c</code>. 2993 */ 2994 public static String valueOf(char c) { 2995 char data[] = {c}; 2996 return new String(0, 1, data); 2997 } 2998 2999 /** 3000 * Returns the string representation of the <code>int</code> argument. 3001 * <p> 3002 * The representation is exactly the one returned by the 3003 * <code>Integer.toString</code> method of one argument. 3004 * 3005 * @param i an <code>int</code>. 3006 * @return a string representation of the <code>int</code> argument. 3007 * @see java.lang.Integer#toString(int, int) 3008 */ 3009 public static String valueOf(int i) { 3010 return Integer.toString(i); 3011 } 3012 3013 /** 3014 * Returns the string representation of the <code>long</code> argument. 3015 * <p> 3016 * The representation is exactly the one returned by the 3017 * <code>Long.toString</code> method of one argument. 3018 * 3019 * @param l a <code>long</code>. 3020 * @return a string representation of the <code>long</code> argument. 3021 * @see java.lang.Long#toString(long) 3022 */ 3023 public static String valueOf(long l) { 3024 return Long.toString(l); 3025 } 3026 3027 /** 3028 * Returns the string representation of the <code>float</code> argument. 3029 * <p> 3030 * The representation is exactly the one returned by the 3031 * <code>Float.toString</code> method of one argument. 3032 * 3033 * @param f a <code>float</code>. 3034 * @return a string representation of the <code>float</code> argument. 3035 * @see java.lang.Float#toString(float) 3036 */ 3037 public static String valueOf(float f) { 3038 return Float.toString(f); 3039 } 3040 3041 /** 3042 * Returns the string representation of the <code>double</code> argument. 3043 * <p> 3044 * The representation is exactly the one returned by the 3045 * <code>Double.toString</code> method of one argument. 3046 * 3047 * @param d a <code>double</code>. 3048 * @return a string representation of the <code>double</code> argument. 3049 * @see java.lang.Double#toString(double) 3050 */ 3051 public static String valueOf(double d) { 3052 return Double.toString(d); 3053 } 3054 3055 /** 3056 * Returns a canonical representation for the string object. 3057 * <p> 3058 * A pool of strings, initially empty, is maintained privately by the 3059 * class <code>String</code>. 3060 * <p> 3061 * When the intern method is invoked, if the pool already contains a 3062 * string equal to this <code>String</code> object as determined by 3063 * the {@link #equals(Object)} method, then the string from the pool is 3064 * returned. Otherwise, this <code>String</code> object is added to the 3065 * pool and a reference to this <code>String</code> object is returned. 3066 * <p> 3067 * It follows that for any two strings <code>s</code> and <code>t</code>, 3068 * <code>s.intern() == t.intern()</code> is <code>true</code> 3069 * if and only if <code>s.equals(t)</code> is <code>true</code>. 3070 * <p> 3071 * All literal strings and string-valued constant expressions are 3072 * interned. String literals are defined in section 3.10.5 of the 3073 * <cite>The Java™ Language Specification</cite>. 3074 * 3075 * @return a string that has the same contents as this string, but is 3076 * guaranteed to be from a pool of unique strings. 3077 */ 3078 public native String intern(); 3079 3080 } | 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang; 27 28 import java.io.ObjectStreamClass; 29 import java.io.ObjectStreamField; 30 import java.io.UnsupportedEncodingException; 31 import java.nio.charset.Charset; 32 import java.util.ArrayList; 33 import java.util.Arrays; 34 import java.util.Comparator; 35 import java.util.Formatter; 36 import java.util.Locale; 37 import java.util.regex.Matcher; 38 import java.util.regex.Pattern; 39 import java.util.regex.PatternSyntaxException; 40 41 /** 42 * The {@code String} class represents character strings. All 43 * string literals in Java programs, such as {@code "abc"}, are 44 * implemented as instances of this class. 45 * <p> 46 * Strings are constant; their values cannot be changed after they 47 * are created. String buffers support mutable strings. 48 * Because String objects are immutable they can be shared. For example: 49 * <p><blockquote><pre> 50 * String str = "abc"; 51 * </pre></blockquote><p> 52 * is equivalent to: 53 * <p><blockquote><pre> 54 * char data[] = {'a', 'b', 'c'}; 55 * String str = new String(data); 56 * </pre></blockquote><p> 57 * Here are some more examples of how strings can be used: 58 * <p><blockquote><pre> 59 * System.out.println("abc"); 60 * String cde = "cde"; 61 * System.out.println("abc" + cde); 62 * String c = "abc".substring(2,3); 63 * String d = cde.substring(1, 2); 64 * </pre></blockquote> 65 * <p> 66 * The class {@code String} includes methods for examining 67 * individual characters of the sequence, for comparing strings, for 68 * searching strings, for extracting substrings, and for creating a 69 * copy of a string with all characters translated to uppercase or to 70 * lowercase. Case mapping is based on the Unicode Standard version 71 * specified by the {@link java.lang.Character Character} class. 72 * <p> 73 * The Java language provides special support for the string 74 * concatenation operator ( + ), and for conversion of 75 * other objects to strings. String concatenation is implemented 76 * through the {@code StringBuilder}(or {@code StringBuffer}) 77 * class and its {@code append} method. 78 * String conversions are implemented through the method 79 * {@code toString}, defined by {@code Object} and 80 * inherited by all classes in Java. For additional information on 81 * string concatenation and conversion, see Gosling, Joy, and Steele, 82 * <i>The Java Language Specification</i>. 83 * 84 * <p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor 85 * or method in this class will cause a {@link NullPointerException} to be 86 * thrown. 87 * 88 * <p>A {@code String} represents a string in the UTF-16 format 89 * in which <em>supplementary characters</em> are represented by <em>surrogate 90 * pairs</em> (see the section <a href="Character.html#unicode">Unicode 91 * Character Representations</a> in the {@code Character} class for 92 * more information). 93 * Index values refer to {@code char} code units, so a supplementary 94 * character uses two positions in a {@code String}. 95 * <p>The {@code String} class provides methods for dealing with 96 * Unicode code points (i.e., characters), in addition to those for 97 * dealing with Unicode code units (i.e., {@code char} values). 98 * 99 * @author Lee Boynton 100 * @author Arthur van Hoff 101 * @author Martin Buchholz 102 * @author Ulf Zibis 103 * @see java.lang.Object#toString() 104 * @see java.lang.StringBuffer 105 * @see java.lang.StringBuilder 106 * @see java.nio.charset.Charset 107 * @since JDK1.0 108 */ 109 110 public final class String 111 implements java.io.Serializable, Comparable<String>, CharSequence 112 { 113 /** The value is used for character storage. */ 114 private final char value[]; 115 116 /** The offset is the first index of the storage that is used. */ 117 private final int offset; 118 119 /** The count is the number of characters in the String. */ 120 private final int count; 121 122 /** Cache the hash code for the string */ 123 private int hash; // Default to 0 124 125 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 126 private static final long serialVersionUID = -6849794470754667710L; 127 128 /** 129 * Class String is special cased within the Serialization Stream Protocol. 130 * 131 * A String instance is written initially into an ObjectOutputStream in the 132 * following format: 133 * <pre> 134 * {@code TC_STRING} (utf String) 135 * </pre> 136 * The String is written by method {@code DataOutput.writeUTF}. 137 * A new handle is generated to refer to all future references to the 138 * string instance within the stream. 139 */ 140 private static final ObjectStreamField[] serialPersistentFields = 141 new ObjectStreamField[0]; 142 143 /** 144 * Initializes a newly created {@code String} object so that it represents 145 * an empty character sequence. Note that use of this constructor is 146 * unnecessary since Strings are immutable. 147 */ 148 public String() { 149 this.offset = 0; 150 this.count = 0; 151 this.value = new char[0]; 152 } 153 154 /** 155 * Initializes a newly created {@code String} object so that it represents 156 * the same sequence of characters as the argument; in other words, the 656 * @return the length of the sequence of characters represented by this 657 * object. 658 */ 659 public int length() { 660 return count; 661 } 662 663 /** 664 * Returns <tt>true</tt> if, and only if, {@link #length()} is <tt>0</tt>. 665 * 666 * @return <tt>true</tt> if {@link #length()} is <tt>0</tt>, otherwise 667 * <tt>false</tt> 668 * 669 * @since 1.6 670 */ 671 public boolean isEmpty() { 672 return count == 0; 673 } 674 675 /** 676 * Returns the {@code char} value at the 677 * specified index. An index ranges from {@code 0} to 678 * {@code length() - 1}. The first {@code char} value of the sequence 679 * is at index {@code 0}, the next at index {@code 1}, 680 * and so on, as for array indexing. 681 * 682 * <p>If the {@code char} value specified by the index is a 683 * <a href="Character.html#unicode">surrogate</a>, the surrogate 684 * value is returned. 685 * 686 * @param index the index of the {@code char} value. 687 * @return the {@code char} value at the specified index of this string. 688 * The first {@code char} value is at index {@code 0}. 689 * @exception IndexOutOfBoundsException if the {@code index} 690 * argument is negative or not less than the length of this 691 * string. 692 */ 693 public char charAt(int index) { 694 if ((index < 0) || (index >= count)) { 695 throw new StringIndexOutOfBoundsException(index); 696 } 697 return value[index + offset]; 698 } 699 700 /** 701 * Returns the character (Unicode code point) at the specified 702 * index. The index refers to {@code char} values 703 * (Unicode code units) and ranges from {@code 0} to 704 * {@link #length()}{@code - 1}. 705 * 706 * <p> If the {@code char} value specified at the given index 707 * is in the high-surrogate range, the following index is less 708 * than the length of this {@code String}, and the 709 * {@code char} value at the following index is in the 710 * low-surrogate range, then the supplementary code point 711 * corresponding to this surrogate pair is returned. Otherwise, 712 * the {@code char} value at the given index is returned. 713 * 714 * @param index the index to the {@code char} values 715 * @return the code point value of the character at the 716 * {@code index} 717 * @exception IndexOutOfBoundsException if the {@code index} 718 * argument is negative or not less than the length of this 719 * string. 720 * @since 1.5 721 */ 722 public int codePointAt(int index) { 723 if ((index < 0) || (index >= count)) { 724 throw new StringIndexOutOfBoundsException(index); 725 } 726 return Character.codePointAtImpl(value, offset + index, offset + count); 727 } 728 729 /** 730 * Returns the character (Unicode code point) before the specified 731 * index. The index refers to {@code char} values 732 * (Unicode code units) and ranges from {@code 1} to {@link 733 * CharSequence#length() length}. 734 * 735 * <p> If the {@code char} value at {@code (index - 1)} 736 * is in the low-surrogate range, {@code (index - 2)} is not 737 * negative, and the {@code char} value at {@code (index - 738 * 2)} is in the high-surrogate range, then the 739 * supplementary code point value of the surrogate pair is 740 * returned. If the {@code char} value at {@code index - 741 * 1} is an unpaired low-surrogate or a high-surrogate, the 742 * surrogate value is returned. 743 * 744 * @param index the index following the code point that should be returned 745 * @return the Unicode code point value before the given index. 746 * @exception IndexOutOfBoundsException if the {@code index} 747 * argument is less than 1 or greater than the length 748 * of this string. 749 * @since 1.5 750 */ 751 public int codePointBefore(int index) { 752 int i = index - 1; 753 if ((i < 0) || (i >= count)) { 754 throw new StringIndexOutOfBoundsException(index); 755 } 756 return Character.codePointBeforeImpl(value, offset + index, offset); 757 } 758 759 /** 760 * Returns the number of Unicode code points in the specified text 761 * range of this {@code String}. The text range begins at the 762 * specified {@code beginIndex} and extends to the 763 * {@code char} at index {@code endIndex - 1}. Thus the 764 * length (in {@code char}s) of the text range is 765 * {@code endIndex-beginIndex}. Unpaired surrogates within 766 * the text range count as one code point each. 767 * 768 * @param beginIndex the index to the first {@code char} of 769 * the text range. 770 * @param endIndex the index after the last {@code char} of 771 * the text range. 772 * @return the number of Unicode code points in the specified text 773 * range 774 * @exception IndexOutOfBoundsException if the 775 * {@code beginIndex} is negative, or {@code endIndex} 776 * is larger than the length of this {@code String}, or 777 * {@code beginIndex} is larger than {@code endIndex}. 778 * @since 1.5 779 */ 780 public int codePointCount(int beginIndex, int endIndex) { 781 if (beginIndex < 0 || endIndex > count || beginIndex > endIndex) { 782 throw new IndexOutOfBoundsException(); 783 } 784 return Character.codePointCountImpl(value, offset+beginIndex, endIndex-beginIndex); 785 } 786 787 /** 788 * Returns the index within this {@code String} that is 789 * offset from the given {@code index} by 790 * {@code codePointOffset} code points. Unpaired surrogates 791 * within the text range given by {@code index} and 792 * {@code codePointOffset} count as one code point each. 793 * 794 * @param index the index to be offset 795 * @param codePointOffset the offset in code points 796 * @return the index within this {@code String} 797 * @exception IndexOutOfBoundsException if {@code index} 798 * is negative or larger then the length of this 799 * {@code String}, or if {@code codePointOffset} is positive 800 * and the substring starting with {@code index} has fewer 801 * than {@code codePointOffset} code points, 802 * or if {@code codePointOffset} is negative and the substring 803 * before {@code index} has fewer than the absolute value 804 * of {@code codePointOffset} code points. 805 * @since 1.5 806 */ 807 public int offsetByCodePoints(int index, int codePointOffset) { 808 if (index < 0 || index > count) { 809 throw new IndexOutOfBoundsException(); 810 } 811 return Character.offsetByCodePointsImpl(value, offset, count, 812 offset+index, codePointOffset) - offset; 813 } 814 815 /** 816 * Copy characters from this string into dst starting at dstBegin. 817 * This method doesn't perform any range checking. 818 */ 819 void getChars(char dst[], int dstBegin) { 820 System.arraycopy(value, offset, dst, dstBegin, count); 821 } 822 823 /** 824 * Copies characters from this string into the destination character 825 * array. 826 * <p> 827 * The first character to be copied is at index {@code srcBegin}; 828 * the last character to be copied is at index {@code srcEnd-1} 829 * (thus the total number of characters to be copied is 830 * {@code srcEnd-srcBegin}). The characters are copied into the 831 * subarray of {@code dst} starting at index {@code dstBegin} 832 * and ending at index: 833 * <p><blockquote><pre> 834 * dstbegin + (srcEnd-srcBegin) - 1 835 * </pre></blockquote> 836 * 837 * @param srcBegin index of the first character in the string 838 * to copy. 839 * @param srcEnd index after the last character in the string 840 * to copy. 841 * @param dst the destination array. 842 * @param dstBegin the start offset in the destination array. 843 * @exception IndexOutOfBoundsException If any of the following 844 * is true: 845 * <ul><li>{@code srcBegin} is negative. 846 * <li>{@code srcBegin} is greater than {@code srcEnd} 847 * <li>{@code srcEnd} is greater than the length of this 848 * string 849 * <li>{@code dstBegin} is negative 850 * <li>{@code dstBegin+(srcEnd-srcBegin)} is larger than 851 * {@code dst.length}</ul> 852 */ 853 public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) { 854 if (srcBegin < 0) { 855 throw new StringIndexOutOfBoundsException(srcBegin); 856 } 857 if (srcEnd > count) { 858 throw new StringIndexOutOfBoundsException(srcEnd); 859 } 860 if (srcBegin > srcEnd) { 861 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin); 862 } 863 System.arraycopy(value, offset + srcBegin, dst, dstBegin, 864 srcEnd - srcBegin); 865 } 866 867 /** 868 * Copies characters from this string into the destination byte array. Each 869 * byte receives the 8 low-order bits of the corresponding character. The 870 * eight high-order bits of each character are not copied and do not 871 * participate in the transfer in any way. 1118 * 1119 * @param anotherString 1120 * The {@code String} to compare this {@code String} against 1121 * 1122 * @return {@code true} if the argument is not {@code null} and it 1123 * represents an equivalent {@code String} ignoring case; {@code 1124 * false} otherwise 1125 * 1126 * @see #equals(Object) 1127 */ 1128 public boolean equalsIgnoreCase(String anotherString) { 1129 return (this == anotherString) ? true : 1130 (anotherString != null) && (anotherString.count == count) && 1131 regionMatches(true, 0, anotherString, 0, count); 1132 } 1133 1134 /** 1135 * Compares two strings lexicographically. 1136 * The comparison is based on the Unicode value of each character in 1137 * the strings. The character sequence represented by this 1138 * {@code String} object is compared lexicographically to the 1139 * character sequence represented by the argument string. The result is 1140 * a negative integer if this {@code String} object 1141 * lexicographically precedes the argument string. The result is a 1142 * positive integer if this {@code String} object lexicographically 1143 * follows the argument string. The result is zero if the strings 1144 * are equal; {@code compareTo} returns {@code 0} exactly when 1145 * the {@link #equals(Object)} method would return {@code true}. 1146 * <p> 1147 * This is the definition of lexicographic ordering. If two strings are 1148 * different, then either they have different characters at some index 1149 * that is a valid index for both strings, or their lengths are different, 1150 * or both. If they have different characters at one or more index 1151 * positions, let <i>k</i> be the smallest such index; then the string 1152 * whose character at position <i>k</i> has the smaller value, as 1153 * determined by using the < operator, lexicographically precedes the 1154 * other string. In this case, {@code compareTo} returns the 1155 * difference of the two character values at position {@code k} in 1156 * the two string -- that is, the value: 1157 * <blockquote><pre> 1158 * this.charAt(k)-anotherString.charAt(k) 1159 * </pre></blockquote> 1160 * If there is no index position at which they differ, then the shorter 1161 * string lexicographically precedes the longer string. In this case, 1162 * {@code compareTo} returns the difference of the lengths of the 1163 * strings -- that is, the value: 1164 * <blockquote><pre> 1165 * this.length()-anotherString.length() 1166 * </pre></blockquote> 1167 * 1168 * @param anotherString the {@code String} to be compared. 1169 * @return the value {@code 0} if the argument string is equal to 1170 * this string; a value less than {@code 0} if this string 1171 * is lexicographically less than the string argument; and a 1172 * value greater than {@code 0} if this string is 1173 * lexicographically greater than the string argument. 1174 */ 1175 public int compareTo(String anotherString) { 1176 int len1 = count; 1177 int len2 = anotherString.count; 1178 int n = Math.min(len1, len2); 1179 char v1[] = value; 1180 char v2[] = anotherString.value; 1181 int i = offset; 1182 int j = anotherString.offset; 1183 1184 if (i == j) { 1185 int k = i; 1186 int lim = n + i; 1187 while (k < lim) { 1188 char c1 = v1[k]; 1189 char c2 = v2[k]; 1190 if (c1 != c2) { 1191 return c1 - c2; 1192 } 1193 k++; 1194 } 1195 } else { 1196 while (n-- != 0) { 1197 char c1 = v1[i++]; 1198 char c2 = v2[j++]; 1199 if (c1 != c2) { 1200 return c1 - c2; 1201 } 1202 } 1203 } 1204 return len1 - len2; 1205 } 1206 1207 /** 1208 * A Comparator that orders {@code String} objects as by 1209 * {@code compareToIgnoreCase}. This comparator is serializable. 1210 * <p> 1211 * Note that this Comparator does <em>not</em> take locale into account, 1212 * and will result in an unsatisfactory ordering for certain locales. 1213 * The java.text package provides <em>Collators</em> to allow 1214 * locale-sensitive ordering. 1215 * 1216 * @see java.text.Collator#compare(String, String) 1217 * @since 1.2 1218 */ 1219 public static final Comparator<String> CASE_INSENSITIVE_ORDER 1220 = new CaseInsensitiveComparator(); 1221 private static class CaseInsensitiveComparator 1222 implements Comparator<String>, java.io.Serializable { 1223 // use serialVersionUID from JDK 1.2.2 for interoperability 1224 private static final long serialVersionUID = 8575799808933029326L; 1225 1226 public int compare(String s1, String s2) { 1227 int n1 = s1.length(); 1228 int n2 = s2.length(); 1229 int min = Math.min(n1, n2); 1236 if (c1 != c2) { 1237 c1 = Character.toLowerCase(c1); 1238 c2 = Character.toLowerCase(c2); 1239 if (c1 != c2) { 1240 // No overflow because of numeric promotion 1241 return c1 - c2; 1242 } 1243 } 1244 } 1245 } 1246 return n1 - n2; 1247 } 1248 1249 /** Replaces the de-serialized object. */ 1250 private Object readResolve() { return CASE_INSENSITIVE_ORDER; } 1251 } 1252 1253 /** 1254 * Compares two strings lexicographically, ignoring case 1255 * differences. This method returns an integer whose sign is that of 1256 * calling {@code compareTo} with normalized versions of the strings 1257 * where case differences have been eliminated by calling 1258 * {@code Character.toLowerCase(Character.toUpperCase(character))} on 1259 * each character. 1260 * <p> 1261 * Note that this method does <em>not</em> take locale into account, 1262 * and will result in an unsatisfactory ordering for certain locales. 1263 * The java.text package provides <em>collators</em> to allow 1264 * locale-sensitive ordering. 1265 * 1266 * @param str the {@code String} to be compared. 1267 * @return a negative integer, zero, or a positive integer as the 1268 * specified String is greater than, equal to, or less 1269 * than this String, ignoring case considerations. 1270 * @see java.text.Collator#compare(String, String) 1271 * @since 1.2 1272 */ 1273 public int compareToIgnoreCase(String str) { 1274 return CASE_INSENSITIVE_ORDER.compare(this, str); 1275 } 1276 1277 /** 1278 * Tests if two string regions are equal. 1279 * <p> 1280 * A substring of this <tt>String</tt> object is compared to a substring 1281 * of the argument other. The result is true if these substrings 1282 * represent identical character sequences. The substring of this 1283 * <tt>String</tt> object to be compared begins at index <tt>toffset</tt> 1284 * and has length <tt>len</tt>. The substring of other to be compared 1285 * begins at index <tt>ooffset</tt> and has length <tt>len</tt>. The 1286 * result is <tt>false</tt> if and only if at least one of the following 1287 * is true: 1288 * <ul><li><tt>toffset</tt> is negative. 1289 * <li><tt>ooffset</tt> is negative. 1290 * <li><tt>toffset+len</tt> is greater than the length of this 1291 * <tt>String</tt> object. 1292 * <li><tt>ooffset+len</tt> is greater than the length of the other 1293 * argument. 1294 * <li>There is some nonnegative integer <i>k</i> less than <tt>len</tt> 1295 * such that: 1296 * <tt>this.charAt(toffset+<i>k</i>) != other.charAt(ooffset+<i>k</i>)</tt> 1297 * </ul> 1298 * 1299 * @param toffset the starting offset of the subregion in this string. 1300 * @param other the string argument. 1301 * @param ooffset the starting offset of the subregion in the string 1302 * argument. 1303 * @param len the number of characters to compare. 1304 * @return {@code true} if the specified subregion of this string 1305 * exactly matches the specified subregion of the string argument; 1306 * {@code false} otherwise. 1307 */ 1308 public boolean regionMatches(int toffset, String other, int ooffset, 1309 int len) { 1310 char ta[] = value; 1311 int to = offset + toffset; 1312 char pa[] = other.value; 1313 int po = other.offset + ooffset; 1314 // Note: toffset, ooffset, or len might be near -1>>>1. 1315 if ((ooffset < 0) || (toffset < 0) || (toffset > (long)count - len) 1316 || (ooffset > (long)other.count - len)) { 1317 return false; 1318 } 1319 while (len-- > 0) { 1320 if (ta[to++] != pa[po++]) { 1321 return false; 1322 } 1323 } 1324 return true; 1325 } 1326 1343 * <li><tt>ooffset+len</tt> is greater than the length of the other 1344 * argument. 1345 * <li><tt>ignoreCase</tt> is <tt>false</tt> and there is some nonnegative 1346 * integer <i>k</i> less than <tt>len</tt> such that: 1347 * <blockquote><pre> 1348 * this.charAt(toffset+k) != other.charAt(ooffset+k) 1349 * </pre></blockquote> 1350 * <li><tt>ignoreCase</tt> is <tt>true</tt> and there is some nonnegative 1351 * integer <i>k</i> less than <tt>len</tt> such that: 1352 * <blockquote><pre> 1353 * Character.toLowerCase(this.charAt(toffset+k)) != 1354 Character.toLowerCase(other.charAt(ooffset+k)) 1355 * </pre></blockquote> 1356 * and: 1357 * <blockquote><pre> 1358 * Character.toUpperCase(this.charAt(toffset+k)) != 1359 * Character.toUpperCase(other.charAt(ooffset+k)) 1360 * </pre></blockquote> 1361 * </ul> 1362 * 1363 * @param ignoreCase if {@code true}, ignore case when comparing 1364 * characters. 1365 * @param toffset the starting offset of the subregion in this 1366 * string. 1367 * @param other the string argument. 1368 * @param ooffset the starting offset of the subregion in the string 1369 * argument. 1370 * @param len the number of characters to compare. 1371 * @return {@code true} if the specified subregion of this string 1372 * matches the specified subregion of the string argument; 1373 * {@code false} otherwise. Whether the matching is exact 1374 * or case insensitive depends on the {@code ignoreCase} 1375 * argument. 1376 */ 1377 public boolean regionMatches(boolean ignoreCase, int toffset, 1378 String other, int ooffset, int len) { 1379 char ta[] = value; 1380 int to = offset + toffset; 1381 char pa[] = other.value; 1382 int po = other.offset + ooffset; 1383 // Note: toffset, ooffset, or len might be near -1>>>1. 1384 if ((ooffset < 0) || (toffset < 0) || (toffset > (long)count - len) || 1385 (ooffset > (long)other.count - len)) { 1386 return false; 1387 } 1388 while (len-- > 0) { 1389 char c1 = ta[to++]; 1390 char c2 = pa[po++]; 1391 if (c1 == c2) { 1392 continue; 1393 } 1394 if (ignoreCase) { 1403 } 1404 // Unfortunately, conversion to uppercase does not work properly 1405 // for the Georgian alphabet, which has strange rules about case 1406 // conversion. So we need to make one last check before 1407 // exiting. 1408 if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) { 1409 continue; 1410 } 1411 } 1412 return false; 1413 } 1414 return true; 1415 } 1416 1417 /** 1418 * Tests if the substring of this string beginning at the 1419 * specified index starts with the specified prefix. 1420 * 1421 * @param prefix the prefix. 1422 * @param toffset where to begin looking in this string. 1423 * @return {@code true} if the character sequence represented by the 1424 * argument is a prefix of the substring of this object starting 1425 * at index {@code toffset}; {@code false} otherwise. 1426 * The result is {@code false} if {@code toffset} is 1427 * negative or greater than the length of this 1428 * {@code String} object; otherwise the result is the same 1429 * as the result of the expression 1430 * <pre> 1431 * this.substring(toffset).startsWith(prefix) 1432 * </pre> 1433 */ 1434 public boolean startsWith(String prefix, int toffset) { 1435 char ta[] = value; 1436 int to = offset + toffset; 1437 char pa[] = prefix.value; 1438 int po = prefix.offset; 1439 int pc = prefix.count; 1440 // Note: toffset might be near -1>>>1. 1441 if ((toffset < 0) || (toffset > count - pc)) { 1442 return false; 1443 } 1444 while (--pc >= 0) { 1445 if (ta[to++] != pa[po++]) { 1446 return false; 1447 } 1448 } 1449 return true; 1450 } 1451 1452 /** 1453 * Tests if this string starts with the specified prefix. 1454 * 1455 * @param prefix the prefix. 1456 * @return {@code true} if the character sequence represented by the 1457 * argument is a prefix of the character sequence represented by 1458 * this string; {@code false} otherwise. 1459 * Note also that {@code true} will be returned if the 1460 * argument is an empty string or is equal to this 1461 * {@code String} object as determined by the 1462 * {@link #equals(Object)} method. 1463 * @since 1. 0 1464 */ 1465 public boolean startsWith(String prefix) { 1466 return startsWith(prefix, 0); 1467 } 1468 1469 /** 1470 * Tests if this string ends with the specified suffix. 1471 * 1472 * @param suffix the suffix. 1473 * @return {@code true} if the character sequence represented by the 1474 * argument is a suffix of the character sequence represented by 1475 * this object; {@code false} otherwise. Note that the 1476 * result will be {@code true} if the argument is the 1477 * empty string or is equal to this {@code String} object 1478 * as determined by the {@link #equals(Object)} method. 1479 */ 1480 public boolean endsWith(String suffix) { 1481 return startsWith(suffix, count - suffix.count); 1482 } 1483 1484 /** 1485 * Returns a hash code for this string. The hash code for a 1486 * {@code String} object is computed as 1487 * <blockquote><pre> 1488 * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1] 1489 * </pre></blockquote> 1490 * using {@code int} arithmetic, where {@code s[i]} is the 1491 * <i>i</i>th character of the string, {@code n} is the length of 1492 * the string, and {@code ^} indicates exponentiation. 1493 * (The hash value of the empty string is zero.) 1494 * 1495 * @return a hash code value for this object. 1496 */ 1497 public int hashCode() { 1498 int h = hash; 1499 if (h == 0 && count > 0) { 1500 int off = offset; 1501 char val[] = value; 1502 int len = count; 1503 1504 for (int i = 0; i < len; i++) { 1505 h = 31*h + val[off++]; 1506 } 1507 hash = h; 1508 } 1509 return h; 1510 } 1511 1512 /** 1513 * Returns the index within this string of the first occurrence of 1514 * the specified character. If a character with value 1515 * {@code ch} occurs in the character sequence represented by 1516 * this {@code String} object, then the index (in Unicode 1517 * code units) of the first such occurrence is returned. For 1518 * values of {@code ch} in the range from 0 to 0xFFFF 1519 * (inclusive), this is the smallest value <i>k</i> such that: 1520 * <blockquote><pre> 1521 * this.charAt(<i>k</i>) == ch 1522 * </pre></blockquote> 1523 * is true. For other values of {@code ch}, it is the 1524 * smallest value <i>k</i> such that: 1525 * <blockquote><pre> 1526 * this.codePointAt(<i>k</i>) == ch 1527 * </pre></blockquote> 1528 * is true. In either case, if no such character occurs in this 1529 * string, then {@code -1} is returned. 1530 * 1531 * @param ch a character (Unicode code point). 1532 * @return the index of the first occurrence of the character in the 1533 * character sequence represented by this object, or 1534 * {@code -1} if the character does not occur. 1535 */ 1536 public int indexOf(int ch) { 1537 return indexOf(ch, 0); 1538 } 1539 1540 /** 1541 * Returns the index within this string of the first occurrence of the 1542 * specified character, starting the search at the specified index. 1543 * <p> 1544 * If a character with value {@code ch} occurs in the 1545 * character sequence represented by this {@code String} 1546 * object at an index no smaller than {@code fromIndex}, then 1547 * the index of the first such occurrence is returned. For values 1548 * of {@code ch} in the range from 0 to 0xFFFF (inclusive), 1549 * this is the smallest value <i>k</i> such that: 1550 * <blockquote><pre> 1551 * (this.charAt(<i>k</i>) == ch) && (<i>k</i> >= fromIndex) 1552 * </pre></blockquote> 1553 * is true. For other values of {@code ch}, it is the 1554 * smallest value <i>k</i> such that: 1555 * <blockquote><pre> 1556 * (this.codePointAt(<i>k</i>) == ch) && (<i>k</i> >= fromIndex) 1557 * </pre></blockquote> 1558 * is true. In either case, if no such character occurs in this 1559 * string at or after position {@code fromIndex}, then 1560 * {@code -1} is returned. 1561 * 1562 * <p> 1563 * There is no restriction on the value of {@code fromIndex}. If it 1564 * is negative, it has the same effect as if it were zero: this entire 1565 * string may be searched. If it is greater than the length of this 1566 * string, it has the same effect as if it were equal to the length of 1567 * this string: {@code -1} is returned. 1568 * 1569 * <p>All indices are specified in {@code char} values 1570 * (Unicode code units). 1571 * 1572 * @param ch a character (Unicode code point). 1573 * @param fromIndex the index to start the search from. 1574 * @return the index of the first occurrence of the character in the 1575 * character sequence represented by this object that is greater 1576 * than or equal to {@code fromIndex}, or {@code -1} 1577 * if the character does not occur. 1578 */ 1579 public int indexOf(int ch, int fromIndex) { 1580 if (fromIndex < 0) { 1581 fromIndex = 0; 1582 } else if (fromIndex >= count) { 1583 // Note: fromIndex might be near -1>>>1. 1584 return -1; 1585 } 1586 1587 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) { 1588 // handle most cases here (ch is a BMP code point or a 1589 // negative value (invalid code point)) 1590 final char[] value = this.value; 1591 final int offset = this.offset; 1592 final int max = offset + count; 1593 for (int i = offset + fromIndex; i < max ; i++) { 1594 if (value[i] == ch) { 1595 return i - offset; 1596 } 1605 * Handles (rare) calls of indexOf with a supplementary character. 1606 */ 1607 private int indexOfSupplementary(int ch, int fromIndex) { 1608 if (Character.isValidCodePoint(ch)) { 1609 final char[] value = this.value; 1610 final int offset = this.offset; 1611 final char hi = Character.highSurrogate(ch); 1612 final char lo = Character.lowSurrogate(ch); 1613 final int max = offset + count - 1; 1614 for (int i = offset + fromIndex; i < max; i++) { 1615 if (value[i] == hi && value[i+1] == lo) { 1616 return i - offset; 1617 } 1618 } 1619 } 1620 return -1; 1621 } 1622 1623 /** 1624 * Returns the index within this string of the last occurrence of 1625 * the specified character. For values of {@code ch} in the 1626 * range from 0 to 0xFFFF (inclusive), the index (in Unicode code 1627 * units) returned is the largest value <i>k</i> such that: 1628 * <blockquote><pre> 1629 * this.charAt(<i>k</i>) == ch 1630 * </pre></blockquote> 1631 * is true. For other values of {@code ch}, it is the 1632 * largest value <i>k</i> such that: 1633 * <blockquote><pre> 1634 * this.codePointAt(<i>k</i>) == ch 1635 * </pre></blockquote> 1636 * is true. In either case, if no such character occurs in this 1637 * string, then {@code -1} is returned. The 1638 * {@code String} is searched backwards starting at the last 1639 * character. 1640 * 1641 * @param ch a character (Unicode code point). 1642 * @return the index of the last occurrence of the character in the 1643 * character sequence represented by this object, or 1644 * {@code -1} if the character does not occur. 1645 */ 1646 public int lastIndexOf(int ch) { 1647 return lastIndexOf(ch, count - 1); 1648 } 1649 1650 /** 1651 * Returns the index within this string of the last occurrence of 1652 * the specified character, searching backward starting at the 1653 * specified index. For values of {@code ch} in the range 1654 * from 0 to 0xFFFF (inclusive), the index returned is the largest 1655 * value <i>k</i> such that: 1656 * <blockquote><pre> 1657 * (this.charAt(<i>k</i>) == ch) && (<i>k</i> <= fromIndex) 1658 * </pre></blockquote> 1659 * is true. For other values of {@code ch}, it is the 1660 * largest value <i>k</i> such that: 1661 * <blockquote><pre> 1662 * (this.codePointAt(<i>k</i>) == ch) && (<i>k</i> <= fromIndex) 1663 * </pre></blockquote> 1664 * is true. In either case, if no such character occurs in this 1665 * string at or before position {@code fromIndex}, then 1666 * {@code -1} is returned. 1667 * 1668 * <p>All indices are specified in {@code char} values 1669 * (Unicode code units). 1670 * 1671 * @param ch a character (Unicode code point). 1672 * @param fromIndex the index to start the search from. There is no 1673 * restriction on the value of {@code fromIndex}. If it is 1674 * greater than or equal to the length of this string, it has 1675 * the same effect as if it were equal to one less than the 1676 * length of this string: this entire string may be searched. 1677 * If it is negative, it has the same effect as if it were -1: 1678 * -1 is returned. 1679 * @return the index of the last occurrence of the character in the 1680 * character sequence represented by this object that is less 1681 * than or equal to {@code fromIndex}, or {@code -1} 1682 * if the character does not occur before that point. 1683 */ 1684 public int lastIndexOf(int ch, int fromIndex) { 1685 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) { 1686 // handle most cases here (ch is a BMP code point or a 1687 // negative value (invalid code point)) 1688 final char[] value = this.value; 1689 final int offset = this.offset; 1690 int i = offset + Math.min(fromIndex, count - 1); 1691 for (; i >= offset ; i--) { 1692 if (value[i] == ch) { 1693 return i - offset; 1694 } 1695 } 1696 return -1; 1697 } else { 1698 return lastIndexOfSupplementary(ch, fromIndex); 1699 } 1700 } 1701 1904 } 1905 } 1906 return start - sourceOffset + 1; 1907 } 1908 } 1909 1910 /** 1911 * Returns a new string that is a substring of this string. The 1912 * substring begins with the character at the specified index and 1913 * extends to the end of this string. <p> 1914 * Examples: 1915 * <blockquote><pre> 1916 * "unhappy".substring(2) returns "happy" 1917 * "Harbison".substring(3) returns "bison" 1918 * "emptiness".substring(9) returns "" (an empty string) 1919 * </pre></blockquote> 1920 * 1921 * @param beginIndex the beginning index, inclusive. 1922 * @return the specified substring. 1923 * @exception IndexOutOfBoundsException if 1924 * {@code beginIndex} is negative or larger than the 1925 * length of this {@code String} object. 1926 */ 1927 public String substring(int beginIndex) { 1928 return substring(beginIndex, count); 1929 } 1930 1931 /** 1932 * Returns a new string that is a substring of this string. The 1933 * substring begins at the specified {@code beginIndex} and 1934 * extends to the character at index {@code endIndex - 1}. 1935 * Thus the length of the substring is {@code endIndex-beginIndex}. 1936 * <p> 1937 * Examples: 1938 * <blockquote><pre> 1939 * "hamburger".substring(4, 8) returns "urge" 1940 * "smiles".substring(1, 5) returns "mile" 1941 * </pre></blockquote> 1942 * 1943 * @param beginIndex the beginning index, inclusive. 1944 * @param endIndex the ending index, exclusive. 1945 * @return the specified substring. 1946 * @exception IndexOutOfBoundsException if the 1947 * {@code beginIndex} is negative, or 1948 * {@code endIndex} is larger than the length of 1949 * this {@code String} object, or 1950 * {@code beginIndex} is larger than 1951 * {@code endIndex}. 1952 */ 1953 public String substring(int beginIndex, int endIndex) { 1954 if (beginIndex < 0) { 1955 throw new StringIndexOutOfBoundsException(beginIndex); 1956 } 1957 if (endIndex > count) { 1958 throw new StringIndexOutOfBoundsException(endIndex); 1959 } 1960 if (beginIndex > endIndex) { 1961 throw new StringIndexOutOfBoundsException(endIndex - beginIndex); 1962 } 1963 return ((beginIndex == 0) && (endIndex == count)) ? this : 1964 new String(offset + beginIndex, endIndex - beginIndex, value); 1965 } 1966 1967 /** 1968 * Returns a new character sequence that is a subsequence of this sequence. 1969 * 1970 * <p> An invocation of this method of the form 1971 * 1982 * 1983 * @param beginIndex the begin index, inclusive. 1984 * @param endIndex the end index, exclusive. 1985 * @return the specified subsequence. 1986 * 1987 * @throws IndexOutOfBoundsException 1988 * if <tt>beginIndex</tt> or <tt>endIndex</tt> are negative, 1989 * if <tt>endIndex</tt> is greater than <tt>length()</tt>, 1990 * or if <tt>beginIndex</tt> is greater than <tt>startIndex</tt> 1991 * 1992 * @since 1.4 1993 * @spec JSR-51 1994 */ 1995 public CharSequence subSequence(int beginIndex, int endIndex) { 1996 return this.substring(beginIndex, endIndex); 1997 } 1998 1999 /** 2000 * Concatenates the specified string to the end of this string. 2001 * <p> 2002 * If the length of the argument string is {@code 0}, then this 2003 * {@code String} object is returned. Otherwise, a new 2004 * {@code String} object is created, representing a character 2005 * sequence that is the concatenation of the character sequence 2006 * represented by this {@code String} object and the character 2007 * sequence represented by the argument string.<p> 2008 * Examples: 2009 * <blockquote><pre> 2010 * "cares".concat("s") returns "caress" 2011 * "to".concat("get").concat("her") returns "together" 2012 * </pre></blockquote> 2013 * 2014 * @param str the {@code String} that is concatenated to the end 2015 * of this {@code String}. 2016 * @return a string that represents the concatenation of this object's 2017 * characters followed by the string argument's characters. 2018 */ 2019 public String concat(String str) { 2020 int otherLen = str.length(); 2021 if (otherLen == 0) { 2022 return this; 2023 } 2024 char buf[] = new char[count + otherLen]; 2025 getChars(0, count, buf, 0); 2026 str.getChars(0, otherLen, buf, count); 2027 return new String(0, count + otherLen, buf); 2028 } 2029 2030 /** 2031 * Returns a new string resulting from replacing all occurrences of 2032 * {@code oldChar} in this string with {@code newChar}. 2033 * <p> 2034 * If the character {@code oldChar} does not occur in the 2035 * character sequence represented by this {@code String} object, 2036 * then a reference to this {@code String} object is returned. 2037 * Otherwise, a new {@code String} object is created that 2038 * represents a character sequence identical to the character sequence 2039 * represented by this {@code String} object, except that every 2040 * occurrence of {@code oldChar} is replaced by an occurrence 2041 * of {@code newChar}. 2042 * <p> 2043 * Examples: 2044 * <blockquote><pre> 2045 * "mesquite in your cellar".replace('e', 'o') 2046 * returns "mosquito in your collar" 2047 * "the war of baronets".replace('r', 'y') 2048 * returns "the way of bayonets" 2049 * "sparring with a purple porpoise".replace('p', 't') 2050 * returns "starring with a turtle tortoise" 2051 * "JonL".replace('q', 'x') returns "JonL" (no change) 2052 * </pre></blockquote> 2053 * 2054 * @param oldChar the old character. 2055 * @param newChar the new character. 2056 * @return a string derived from this string by replacing every 2057 * occurrence of {@code oldChar} with {@code newChar}. 2058 */ 2059 public String replace(char oldChar, char newChar) { 2060 if (oldChar != newChar) { 2061 int len = count; 2062 int i = -1; 2063 char[] val = value; /* avoid getfield opcode */ 2064 int off = offset; /* avoid getfield opcode */ 2065 2066 while (++i < len) { 2067 if (val[off + i] == oldChar) { 2068 break; 2069 } 2070 } 2071 if (i < len) { 2072 char buf[] = new char[len]; 2073 for (int j = 0 ; j < i ; j++) { 2074 buf[j] = val[off+j]; 2075 } 2076 while (i < len) { 2077 char c = val[off + i]; 2102 * @return <tt>true</tt> if, and only if, this string matches the 2103 * given regular expression 2104 * 2105 * @throws PatternSyntaxException 2106 * if the regular expression's syntax is invalid 2107 * 2108 * @see java.util.regex.Pattern 2109 * 2110 * @since 1.4 2111 * @spec JSR-51 2112 */ 2113 public boolean matches(String regex) { 2114 return Pattern.matches(regex, this); 2115 } 2116 2117 /** 2118 * Returns true if and only if this string contains the specified 2119 * sequence of char values. 2120 * 2121 * @param s the sequence to search for 2122 * @return true if this string contains {@code s}, false otherwise 2123 * @throws NullPointerException if {@code s} is {@code null} 2124 * @since 1.5 2125 */ 2126 public boolean contains(CharSequence s) { 2127 return indexOf(s.toString()) > -1; 2128 } 2129 2130 /** 2131 * Replaces the first substring of this string that matches the given <a 2132 * href="../util/regex/Pattern.html#sum">regular expression</a> with the 2133 * given replacement. 2134 * 2135 * <p> An invocation of this method of the form 2136 * <i>str</i><tt>.replaceFirst(</tt><i>regex</i><tt>,</tt> <i>repl</i><tt>)</tt> 2137 * yields exactly the same result as the expression 2138 * 2139 * <blockquote><tt> 2140 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile 2141 * compile}(</tt><i>regex</i><tt>).{@link 2142 * java.util.regex.Pattern#matcher(java.lang.CharSequence) 2143 * matcher}(</tt><i>str</i><tt>).{@link java.util.regex.Matcher#replaceFirst 2206 * 2207 * @see java.util.regex.Pattern 2208 * 2209 * @since 1.4 2210 * @spec JSR-51 2211 */ 2212 public String replaceAll(String regex, String replacement) { 2213 return Pattern.compile(regex).matcher(this).replaceAll(replacement); 2214 } 2215 2216 /** 2217 * Replaces each substring of this string that matches the literal target 2218 * sequence with the specified literal replacement sequence. The 2219 * replacement proceeds from the beginning of the string to the end, for 2220 * example, replacing "aa" with "b" in the string "aaa" will result in 2221 * "ba" rather than "ab". 2222 * 2223 * @param target The sequence of char values to be replaced 2224 * @param replacement The replacement sequence of char values 2225 * @return The resulting string 2226 * @throws NullPointerException if {@code target} or 2227 * {@code replacement} is {@code null}. 2228 * @since 1.5 2229 */ 2230 public String replace(CharSequence target, CharSequence replacement) { 2231 return Pattern.compile(target.toString(), Pattern.LITERAL).matcher( 2232 this).replaceAll(Matcher.quoteReplacement(replacement.toString())); 2233 } 2234 2235 /** 2236 * Splits this string around matches of the given 2237 * <a href="../util/regex/Pattern.html#sum">regular expression</a>. 2238 * 2239 * <p> The array returned by this method contains each substring of this 2240 * string that is terminated by another substring that matches the given 2241 * expression or is terminated by the end of the string. The substrings in 2242 * the array are in the order in which they occur in this string. If the 2243 * expression does not match any part of the input then the resulting array 2244 * has just one element, namely this string. 2245 * 2246 * <p> The <tt>limit</tt> parameter controls the number of times the 2247 * pattern is applied and therefore affects the length of the resulting 2390 * 2391 * @param regex 2392 * the delimiting regular expression 2393 * 2394 * @return the array of strings computed by splitting this string 2395 * around matches of the given regular expression 2396 * 2397 * @throws PatternSyntaxException 2398 * if the regular expression's syntax is invalid 2399 * 2400 * @see java.util.regex.Pattern 2401 * 2402 * @since 1.4 2403 * @spec JSR-51 2404 */ 2405 public String[] split(String regex) { 2406 return split(regex, 0); 2407 } 2408 2409 /** 2410 * Converts all of the characters in this {@code String} to lower 2411 * case using the rules of the given {@code Locale}. Case mapping is based 2412 * on the Unicode Standard version specified by the {@link java.lang.Character Character} 2413 * class. Since case mappings are not always 1:1 char mappings, the resulting 2414 * {@code String} may be a different length than the original {@code String}. 2415 * <p> 2416 * Examples of lowercase mappings are in the following table: 2417 * <table border="1" summary="Lowercase mapping examples showing language code of locale, upper case, lower case, and description"> 2418 * <tr> 2419 * <th>Language Code of Locale</th> 2420 * <th>Upper Case</th> 2421 * <th>Lower Case</th> 2422 * <th>Description</th> 2423 * </tr> 2424 * <tr> 2425 * <td>tr (Turkish)</td> 2426 * <td>\u0130</td> 2427 * <td>\u0069</td> 2428 * <td>capital letter I with dot above -> small letter i</td> 2429 * </tr> 2430 * <tr> 2431 * <td>tr (Turkish)</td> 2432 * <td>\u0049</td> 2433 * <td>\u0131</td> 2434 * <td>capital letter I -> small letter dotless i </td> 2435 * </tr> 2436 * <tr> 2437 * <td>(all)</td> 2438 * <td>French Fries</td> 2439 * <td>french fries</td> 2440 * <td>lowercased all chars in String</td> 2441 * </tr> 2442 * <tr> 2443 * <td>(all)</td> 2444 * <td><img src="doc-files/capiota.gif" alt="capiota"><img src="doc-files/capchi.gif" alt="capchi"> 2445 * <img src="doc-files/captheta.gif" alt="captheta"><img src="doc-files/capupsil.gif" alt="capupsil"> 2446 * <img src="doc-files/capsigma.gif" alt="capsigma"></td> 2447 * <td><img src="doc-files/iota.gif" alt="iota"><img src="doc-files/chi.gif" alt="chi"> 2448 * <img src="doc-files/theta.gif" alt="theta"><img src="doc-files/upsilon.gif" alt="upsilon"> 2449 * <img src="doc-files/sigma1.gif" alt="sigma"></td> 2450 * <td>lowercased all chars in String</td> 2451 * </tr> 2452 * </table> 2453 * 2454 * @param locale use the case transformation rules for this locale 2455 * @return the {@code String}, converted to lowercase. 2456 * @see java.lang.String#toLowerCase() 2457 * @see java.lang.String#toUpperCase() 2458 * @see java.lang.String#toUpperCase(Locale) 2459 * @since 1.1 2460 */ 2461 public String toLowerCase(Locale locale) { 2462 if (locale == null) { 2463 throw new NullPointerException(); 2464 } 2465 2466 int firstUpper; 2467 2468 /* Now check if there are any characters that need to be changed. */ 2469 scan: { 2470 for (firstUpper = 0 ; firstUpper < count; ) { 2471 char c = value[offset+firstUpper]; 2472 if ((c >= Character.MIN_HIGH_SURROGATE) && 2473 (c <= Character.MAX_HIGH_SURROGATE)) { 2474 int supplChar = codePointAt(firstUpper); 2475 if (supplChar != Character.toLowerCase(supplChar)) { 2536 /* Grow result if needed */ 2537 int mapLen = lowerCharArray.length; 2538 if (mapLen > srcCount) { 2539 char[] result2 = new char[result.length + mapLen - srcCount]; 2540 System.arraycopy(result, 0, result2, 0, 2541 i + resultOffset); 2542 result = result2; 2543 } 2544 for (int x=0; x<mapLen; ++x) { 2545 result[i+resultOffset+x] = lowerCharArray[x]; 2546 } 2547 resultOffset += (mapLen - srcCount); 2548 } else { 2549 result[i+resultOffset] = (char)lowerChar; 2550 } 2551 } 2552 return new String(0, count+resultOffset, result); 2553 } 2554 2555 /** 2556 * Converts all of the characters in this {@code String} to lower 2557 * case using the rules of the default locale. This is equivalent to calling 2558 * {@code toLowerCase(Locale.getDefault())}. 2559 * <p> 2560 * <b>Note:</b> This method is locale sensitive, and may produce unexpected 2561 * results if used for strings that are intended to be interpreted locale 2562 * independently. 2563 * Examples are programming language identifiers, protocol keys, and HTML 2564 * tags. 2565 * For instance, {@code "TITLE".toLowerCase()} in a Turkish locale 2566 * returns {@code "t\u005Cu0131tle"}, where '\u005Cu0131' is the 2567 * LATIN SMALL LETTER DOTLESS I character. 2568 * To obtain correct results for locale insensitive strings, use 2569 * {@code toLowerCase(Locale.ENGLISH)}. 2570 * <p> 2571 * @return the {@code String}, converted to lowercase. 2572 * @see java.lang.String#toLowerCase(Locale) 2573 */ 2574 public String toLowerCase() { 2575 return toLowerCase(Locale.getDefault()); 2576 } 2577 2578 /** 2579 * Converts all of the characters in this {@code String} to upper 2580 * case using the rules of the given {@code Locale}. Case mapping is based 2581 * on the Unicode Standard version specified by the {@link java.lang.Character Character} 2582 * class. Since case mappings are not always 1:1 char mappings, the resulting 2583 * {@code String} may be a different length than the original {@code String}. 2584 * <p> 2585 * Examples of locale-sensitive and 1:M case mappings are in the following table. 2586 * <p> 2587 * <table border="1" summary="Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description."> 2588 * <tr> 2589 * <th>Language Code of Locale</th> 2590 * <th>Lower Case</th> 2591 * <th>Upper Case</th> 2592 * <th>Description</th> 2593 * </tr> 2594 * <tr> 2595 * <td>tr (Turkish)</td> 2596 * <td>\u0069</td> 2597 * <td>\u0130</td> 2598 * <td>small letter i -> capital letter I with dot above</td> 2599 * </tr> 2600 * <tr> 2601 * <td>tr (Turkish)</td> 2602 * <td>\u0131</td> 2603 * <td>\u0049</td> 2604 * <td>small letter dotless i -> capital letter I</td> 2605 * </tr> 2606 * <tr> 2607 * <td>(all)</td> 2608 * <td>\u00df</td> 2609 * <td>\u0053 \u0053</td> 2610 * <td>small letter sharp s -> two letters: SS</td> 2611 * </tr> 2612 * <tr> 2613 * <td>(all)</td> 2614 * <td>Fahrvergnügen</td> 2615 * <td>FAHRVERGNÜGEN</td> 2616 * <td></td> 2617 * </tr> 2618 * </table> 2619 * @param locale use the case transformation rules for this locale 2620 * @return the {@code String}, converted to uppercase. 2621 * @see java.lang.String#toUpperCase() 2622 * @see java.lang.String#toLowerCase() 2623 * @see java.lang.String#toLowerCase(Locale) 2624 * @since 1.1 2625 */ 2626 public String toUpperCase(Locale locale) { 2627 if (locale == null) { 2628 throw new NullPointerException(); 2629 } 2630 2631 int firstLower; 2632 2633 /* Now check if there are any characters that need to be changed. */ 2634 scan: { 2635 for (firstLower = 0 ; firstLower < count; ) { 2636 int c = (int)value[offset+firstLower]; 2637 int srcCount; 2638 if ((c >= Character.MIN_HIGH_SURROGATE) && 2639 (c <= Character.MAX_HIGH_SURROGATE)) { 2640 c = codePointAt(firstLower); 2699 /* Grow result if needed */ 2700 int mapLen = upperCharArray.length; 2701 if (mapLen > srcCount) { 2702 char[] result2 = new char[result.length + mapLen - srcCount]; 2703 System.arraycopy(result, 0, result2, 0, 2704 i + resultOffset); 2705 result = result2; 2706 } 2707 for (int x=0; x<mapLen; ++x) { 2708 result[i+resultOffset+x] = upperCharArray[x]; 2709 } 2710 resultOffset += (mapLen - srcCount); 2711 } else { 2712 result[i+resultOffset] = (char)upperChar; 2713 } 2714 } 2715 return new String(0, count+resultOffset, result); 2716 } 2717 2718 /** 2719 * Converts all of the characters in this {@code String} to upper 2720 * case using the rules of the default locale. This method is equivalent to 2721 * {@code toUpperCase(Locale.getDefault())}. 2722 * <p> 2723 * <b>Note:</b> This method is locale sensitive, and may produce unexpected 2724 * results if used for strings that are intended to be interpreted locale 2725 * independently. 2726 * Examples are programming language identifiers, protocol keys, and HTML 2727 * tags. 2728 * For instance, {@code "title".toUpperCase()} in a Turkish locale 2729 * returns {@code "T\u005Cu0130TLE"}, where '\u005Cu0130' is the 2730 * LATIN CAPITAL LETTER I WITH DOT ABOVE character. 2731 * To obtain correct results for locale insensitive strings, use 2732 * {@code toUpperCase(Locale.ENGLISH)}. 2733 * <p> 2734 * @return the {@code String}, converted to uppercase. 2735 * @see java.lang.String#toUpperCase(Locale) 2736 */ 2737 public String toUpperCase() { 2738 return toUpperCase(Locale.getDefault()); 2739 } 2740 2741 /** 2742 * Returns a copy of the string, with leading and trailing whitespace 2743 * omitted. 2744 * <p> 2745 * If this {@code String} object represents an empty character 2746 * sequence, or the first and last characters of character sequence 2747 * represented by this {@code String} object both have codes 2748 * greater than {@code '\u005Cu0020'} (the space character), then a 2749 * reference to this {@code String} object is returned. 2750 * <p> 2751 * Otherwise, if there is no character with a code greater than 2752 * {@code '\u005Cu0020'} in the string, then a new 2753 * {@code String} object representing an empty string is created 2754 * and returned. 2755 * <p> 2756 * Otherwise, let <i>k</i> be the index of the first character in the 2757 * string whose code is greater than {@code '\u005Cu0020'}, and let 2758 * <i>m</i> be the index of the last character in the string whose code 2759 * is greater than {@code '\u005Cu0020'}. A new {@code String} 2760 * object is created, representing the substring of this string that 2761 * begins with the character at index <i>k</i> and ends with the 2762 * character at index <i>m</i>-that is, the result of 2763 * <code>this.substring(<i>k</i>, <i>m</i>+1)</code>. 2764 * <p> 2765 * This method may be used to trim whitespace (as defined above) from 2766 * the beginning and end of a string. 2767 * 2768 * @return A copy of this string with leading and trailing white 2769 * space removed, or this string if it has no leading or 2770 * trailing white space. 2771 */ 2772 public String trim() { 2773 int len = count; 2774 int st = 0; 2775 int off = offset; /* avoid getfield opcode */ 2776 char[] val = value; /* avoid getfield opcode */ 2777 2778 while ((st < len) && (val[off + st] <= ' ')) { 2779 st++; 2876 * specifier that is incompatible with the given arguments, 2877 * insufficient arguments given the format string, or other 2878 * illegal conditions. For specification of all possible 2879 * formatting errors, see the <a 2880 * href="../util/Formatter.html#detail">Details</a> section of the 2881 * formatter class specification 2882 * 2883 * @throws NullPointerException 2884 * If the <tt>format</tt> is <tt>null</tt> 2885 * 2886 * @return A formatted string 2887 * 2888 * @see java.util.Formatter 2889 * @since 1.5 2890 */ 2891 public static String format(Locale l, String format, Object ... args) { 2892 return new Formatter(l).format(format, args).toString(); 2893 } 2894 2895 /** 2896 * Returns the string representation of the {@code Object} argument. 2897 * 2898 * @param obj an {@code Object}. 2899 * @return if the argument is {@code null}, then a string equal to 2900 * {@code "null"}; otherwise, the value of 2901 * {@code obj.toString()} is returned. 2902 * @see java.lang.Object#toString() 2903 */ 2904 public static String valueOf(Object obj) { 2905 return (obj == null) ? "null" : obj.toString(); 2906 } 2907 2908 /** 2909 * Returns the string representation of the {@code char} array 2910 * argument. The contents of the character array are copied; subsequent 2911 * modification of the character array does not affect the newly 2912 * created string. 2913 * 2914 * @param data a {@code char} array. 2915 * @return a newly allocated string representing the same sequence of 2916 * characters contained in the character array argument. 2917 */ 2918 public static String valueOf(char data[]) { 2919 return new String(data); 2920 } 2921 2922 /** 2923 * Returns the string representation of a specific subarray of the 2924 * {@code char} array argument. 2925 * <p> 2926 * The {@code offset} argument is the index of the first 2927 * character of the subarray. The {@code count} argument 2928 * specifies the length of the subarray. The contents of the subarray 2929 * are copied; subsequent modification of the character array does not 2930 * affect the newly created string. 2931 * 2932 * @param data the character array. 2933 * @param offset the initial offset into the value of the 2934 * {@code String}. 2935 * @param count the length of the value of the {@code String}. 2936 * @return a string representing the sequence of characters contained 2937 * in the subarray of the character array argument. 2938 * @exception IndexOutOfBoundsException if {@code offset} is 2939 * negative, or {@code count} is negative, or 2940 * {@code offset+count} is larger than 2941 * {@code data.length}. 2942 */ 2943 public static String valueOf(char data[], int offset, int count) { 2944 return new String(data, offset, count); 2945 } 2946 2947 /** 2948 * Returns a String that represents the character sequence in the 2949 * array specified. 2950 * 2951 * @param data the character array. 2952 * @param offset initial offset of the subarray. 2953 * @param count length of the subarray. 2954 * @return a {@code String} that contains the characters of the 2955 * specified subarray of the character array. 2956 */ 2957 public static String copyValueOf(char data[], int offset, int count) { 2958 // All public String constructors now copy the data. 2959 return new String(data, offset, count); 2960 } 2961 2962 /** 2963 * Returns a String that represents the character sequence in the 2964 * array specified. 2965 * 2966 * @param data the character array. 2967 * @return a {@code String} that contains the characters of the 2968 * character array. 2969 */ 2970 public static String copyValueOf(char data[]) { 2971 return copyValueOf(data, 0, data.length); 2972 } 2973 2974 /** 2975 * Returns the string representation of the {@code boolean} argument. 2976 * 2977 * @param b a {@code boolean}. 2978 * @return if the argument is {@code true}, a string equal to 2979 * {@code "true"} is returned; otherwise, a string equal to 2980 * {@code "false"} is returned. 2981 */ 2982 public static String valueOf(boolean b) { 2983 return b ? "true" : "false"; 2984 } 2985 2986 /** 2987 * Returns the string representation of the {@code char} 2988 * argument. 2989 * 2990 * @param c a {@code char}. 2991 * @return a string of length {@code 1} containing 2992 * as its single character the argument {@code c}. 2993 */ 2994 public static String valueOf(char c) { 2995 char data[] = {c}; 2996 return new String(0, 1, data); 2997 } 2998 2999 /** 3000 * Returns the string representation of the {@code int} argument. 3001 * <p> 3002 * The representation is exactly the one returned by the 3003 * {@code Integer.toString} method of one argument. 3004 * 3005 * @param i an {@code int}. 3006 * @return a string representation of the {@code int} argument. 3007 * @see java.lang.Integer#toString(int, int) 3008 */ 3009 public static String valueOf(int i) { 3010 return Integer.toString(i); 3011 } 3012 3013 /** 3014 * Returns the string representation of the {@code long} argument. 3015 * <p> 3016 * The representation is exactly the one returned by the 3017 * {@code Long.toString} method of one argument. 3018 * 3019 * @param l a {@code long}. 3020 * @return a string representation of the {@code long} argument. 3021 * @see java.lang.Long#toString(long) 3022 */ 3023 public static String valueOf(long l) { 3024 return Long.toString(l); 3025 } 3026 3027 /** 3028 * Returns the string representation of the {@code float} argument. 3029 * <p> 3030 * The representation is exactly the one returned by the 3031 * {@code Float.toString} method of one argument. 3032 * 3033 * @param f a {@code float}. 3034 * @return a string representation of the {@code float} argument. 3035 * @see java.lang.Float#toString(float) 3036 */ 3037 public static String valueOf(float f) { 3038 return Float.toString(f); 3039 } 3040 3041 /** 3042 * Returns the string representation of the {@code double} argument. 3043 * <p> 3044 * The representation is exactly the one returned by the 3045 * {@code Double.toString} method of one argument. 3046 * 3047 * @param d a {@code double}. 3048 * @return a string representation of the {@code double} argument. 3049 * @see java.lang.Double#toString(double) 3050 */ 3051 public static String valueOf(double d) { 3052 return Double.toString(d); 3053 } 3054 3055 /** 3056 * Returns a canonical representation for the string object. 3057 * <p> 3058 * A pool of strings, initially empty, is maintained privately by the 3059 * class {@code String}. 3060 * <p> 3061 * When the intern method is invoked, if the pool already contains a 3062 * string equal to this {@code String} object as determined by 3063 * the {@link #equals(Object)} method, then the string from the pool is 3064 * returned. Otherwise, this {@code String} object is added to the 3065 * pool and a reference to this {@code String} object is returned. 3066 * <p> 3067 * It follows that for any two strings {@code s} and {@code t}, 3068 * {@code s.intern() == t.intern()} is {@code true} 3069 * if and only if {@code s.equals(t)} is {@code true}. 3070 * <p> 3071 * All literal strings and string-valued constant expressions are 3072 * interned. String literals are defined in section 3.10.5 of the 3073 * <cite>The Java™ Language Specification</cite>. 3074 * 3075 * @return a string that has the same contents as this string, but is 3076 * guaranteed to be from a pool of unique strings. 3077 */ 3078 public native String intern(); 3079 3080 } |