1 /*
2 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 jdk.internal.HotSpotIntrinsicCandidate;
29
30 /**
31 * The Boolean class wraps a value of the primitive type
32 * {@code boolean} in an object. An object of type
33 * {@code Boolean} contains a single field whose type is
34 * {@code boolean}.
35 * <p>
36 * In addition, this class provides many methods for
37 * converting a {@code boolean} to a {@code String} and a
38 * {@code String} to a {@code boolean}, as well as other
39 * constants and methods useful when dealing with a
40 * {@code boolean}.
41 *
42 * @author Arthur van Hoff
43 * @since 1.0
44 */
45 public final class Boolean implements java.io.Serializable,
46 Comparable<Boolean>
47 {
48 /**
49 * The {@code Boolean} object corresponding to the primitive
50 * value {@code true}.
51 */
52 public static final Boolean TRUE = new Boolean(true);
53
54 /**
55 * The {@code Boolean} object corresponding to the primitive
56 * value {@code false}.
57 */
58 public static final Boolean FALSE = new Boolean(false);
59
60 /**
61 * The Class object representing the primitive type boolean.
62 *
63 * @since 1.1
64 */
65 @SuppressWarnings("unchecked")
66 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");
67
68 /**
69 * The value of the Boolean.
70 *
71 * @serial
72 */
73 private final boolean value;
74
75 /** use serialVersionUID from JDK 1.0.2 for interoperability */
76 private static final long serialVersionUID = -3665804199014368530L;
77
78 /**
79 * Allocates a {@code Boolean} object representing the
80 * {@code value} argument.
81 *
82 * <p><b>Note: It is rarely appropriate to use this constructor.
83 * Unless a <i>new</i> instance is required, the static factory
84 * {@link #valueOf(boolean)} is generally a better choice. It is
85 * likely to yield significantly better space and time performance.</b>
86 * @deprecated use {@link #valueOf(boolean)} instead.
87 *
88 * @param value the value of the {@code Boolean}.
89 */
90 @Deprecated
91 public Boolean(boolean value) {
92 this.value = value;
93 }
94
95 /**
96 * Allocates a {@code Boolean} object representing the value
97 * {@code true} if the string argument is not {@code null}
98 * and is equal, ignoring case, to the string {@code "true"}.
99 * Otherwise, allocate a {@code Boolean} object representing the
100 * value {@code false}. Examples:<p>
101 * {@code new Boolean("True")} produces a {@code Boolean} object
102 * that represents {@code true}.<br>
103 * {@code new Boolean("yes")} produces a {@code Boolean} object
104 * that represents {@code false}.
105 * @deprecated use {@link #valueOf(String)} instead.
106 *
107 * @param s the string to be converted to a {@code Boolean}.
108 */
109 @Deprecated
110 public Boolean(String s) {
111 this(parseBoolean(s));
112 }
113
114 /**
115 * Parses the string argument as a boolean. The {@code boolean}
116 * returned represents the value {@code true} if the string argument
117 * is not {@code null} and is equal, ignoring case, to the string
118 * {@code "true"}. <p>
119 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
120 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
121 *
122 * @param s the {@code String} containing the boolean
123 * representation to be parsed
124 * @return the boolean represented by the string argument
125 * @since 1.5
126 */
127 public static boolean parseBoolean(String s) {
128 return ((s != null) && s.equalsIgnoreCase("true"));
129 }
130
131 /**
132 * Returns the value of this {@code Boolean} object as a boolean
133 * primitive.
134 *
135 * @return the primitive {@code boolean} value of this object.
136 */
137 @HotSpotIntrinsicCandidate
138 public boolean booleanValue() {
139 return value;
140 }
141
142 /**
143 * Returns a {@code Boolean} instance representing the specified
144 * {@code boolean} value. If the specified {@code boolean} value
145 * is {@code true}, this method returns {@code Boolean.TRUE};
146 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
147 * If a new {@code Boolean} instance is not required, this method
148 * should generally be used in preference to the constructor
149 * {@link #Boolean(boolean)}, as this method is likely to yield
150 * significantly better space and time performance.
151 *
152 * @param b a boolean value.
153 * @return a {@code Boolean} instance representing {@code b}.
154 * @since 1.4
155 */
156 @HotSpotIntrinsicCandidate
157 public static Boolean valueOf(boolean b) {
158 return (b ? TRUE : FALSE);
159 }
160
161 /**
162 * Returns a {@code Boolean} with a value represented by the
163 * specified string. The {@code Boolean} returned represents a
164 * true value if the string argument is not {@code null}
165 * and is equal, ignoring case, to the string {@code "true"}.
166 *
167 * @param s a string.
168 * @return the {@code Boolean} value represented by the string.
169 */
170 public static Boolean valueOf(String s) {
171 return parseBoolean(s) ? TRUE : FALSE;
172 }
173
174 /**
175 * Returns a {@code String} object representing the specified
176 * boolean. If the specified boolean is {@code true}, then
177 * the string {@code "true"} will be returned, otherwise the
178 * string {@code "false"} will be returned.
179 *
180 * @param b the boolean to be converted
181 * @return the string representation of the specified {@code boolean}
182 * @since 1.4
183 */
184 public static String toString(boolean b) {
185 return b ? "true" : "false";
186 }
187
188 /**
189 * Returns a {@code String} object representing this Boolean's
190 * value. If this object represents the value {@code true},
191 * a string equal to {@code "true"} is returned. Otherwise, a
192 * string equal to {@code "false"} is returned.
193 *
194 * @return a string representation of this object.
195 */
196 public String toString() {
197 return value ? "true" : "false";
198 }
199
200 /**
201 * Returns a hash code for this {@code Boolean} object.
202 *
203 * @return the integer {@code 1231} if this object represents
204 * {@code true}; returns the integer {@code 1237} if this
205 * object represents {@code false}.
206 */
207 @Override
208 public int hashCode() {
209 return Boolean.hashCode(value);
210 }
211
212 /**
213 * Returns a hash code for a {@code boolean} value; compatible with
214 * {@code Boolean.hashCode()}.
215 *
216 * @param value the value to hash
217 * @return a hash code value for a {@code boolean} value.
218 * @since 1.8
219 */
220 public static int hashCode(boolean value) {
221 return value ? 1231 : 1237;
222 }
223
224 /**
225 * Returns {@code true} if and only if the argument is not
226 * {@code null} and is a {@code Boolean} object that
227 * represents the same {@code boolean} value as this object.
228 *
229 * @param obj the object to compare with.
230 * @return {@code true} if the Boolean objects represent the
231 * same value; {@code false} otherwise.
232 */
233 public boolean equals(Object obj) {
234 if (obj instanceof Boolean) {
235 return value == ((Boolean)obj).booleanValue();
236 }
237 return false;
238 }
239
240 /**
241 * Returns {@code true} if and only if the system property named
242 * by the argument exists and is equal to the string {@code
243 * "true"}. (Beginning with version 1.0.2 of the Java™
244 * platform, the test of this string is case insensitive.) A
245 * system property is accessible through {@code getProperty}, a
246 * method defined by the {@code System} class.
247 * <p>
248 * If there is no property with the specified name, or if the specified
249 * name is empty or null, then {@code false} is returned.
250 *
251 * @param name the system property name.
252 * @return the {@code boolean} value of the system property.
253 * @throws SecurityException for the same reasons as
254 * {@link System#getProperty(String) System.getProperty}
255 * @see java.lang.System#getProperty(java.lang.String)
256 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
257 */
258 public static boolean getBoolean(String name) {
259 boolean result = false;
260 try {
261 result = parseBoolean(System.getProperty(name));
262 } catch (IllegalArgumentException | NullPointerException e) {
263 }
264 return result;
265 }
266
267 /**
268 * Compares this {@code Boolean} instance with another.
269 *
270 * @param b the {@code Boolean} instance to be compared
271 * @return zero if this object represents the same boolean value as the
272 * argument; a positive value if this object represents true
273 * and the argument represents false; and a negative value if
274 * this object represents false and the argument represents true
275 * @throws NullPointerException if the argument is {@code null}
276 * @see Comparable
277 * @since 1.5
278 */
279 public int compareTo(Boolean b) {
280 return compare(this.value, b.value);
281 }
282
283 /**
284 * Compares two {@code boolean} values.
285 * The value returned is identical to what would be returned by:
286 * <pre>
287 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
288 * </pre>
289 *
290 * @param x the first {@code boolean} to compare
291 * @param y the second {@code boolean} to compare
292 * @return the value {@code 0} if {@code x == y};
293 * a value less than {@code 0} if {@code !x && y}; and
294 * a value greater than {@code 0} if {@code x && !y}
295 * @since 1.7
296 */
297 public static int compare(boolean x, boolean y) {
298 return (x == y) ? 0 : (x ? 1 : -1);
299 }
300
301 /**
302 * Returns the result of applying the logical AND operator to the
303 * specified {@code boolean} operands.
304 *
305 * @param a the first operand
306 * @param b the second operand
307 * @return the logical AND of {@code a} and {@code b}
308 * @see java.util.function.BinaryOperator
309 * @since 1.8
310 */
311 public static boolean logicalAnd(boolean a, boolean b) {
312 return a && b;
313 }
314
315 /**
316 * Returns the result of applying the logical OR operator to the
317 * specified {@code boolean} operands.
318 *
319 * @param a the first operand
320 * @param b the second operand
321 * @return the logical OR of {@code a} and {@code b}
322 * @see java.util.function.BinaryOperator
323 * @since 1.8
324 */
325 public static boolean logicalOr(boolean a, boolean b) {
326 return a || b;
327 }
328
329 /**
330 * Returns the result of applying the logical XOR operator to the
331 * specified {@code boolean} operands.
332 *
333 * @param a the first operand
334 * @param b the second operand
335 * @return the logical XOR of {@code a} and {@code b}
336 * @see java.util.function.BinaryOperator
337 * @since 1.8
338 */
339 public static boolean logicalXor(boolean a, boolean b) {
340 return a ^ b;
341 }
342 }