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 * @param value the value of the {@code Boolean}.
83 *
84 * @deprecated
85 * It is rarely appropriate to use this constructor. The static factory
86 * {@link #valueOf(boolean)} is generally a better choice, as it is
87 * likely to yield significantly better space and time performance.
88 * Also consider using the final fields {@link #TRUE} and {@link #FALSE}
89 * if possible.
90 */
91 @Deprecated(since="9")
92 public Boolean(boolean value) {
93 this.value = value;
94 }
95
96 /**
97 * Allocates a {@code Boolean} object representing the value
98 * {@code true} if the string argument is not {@code null}
99 * and is equal, ignoring case, to the string {@code "true"}.
100 * Otherwise, allocates a {@code Boolean} object representing the
101 * value {@code false}.
102 *
103 * @param s the string to be converted to a {@code Boolean}.
104 *
105 * @deprecated
106 * It is rarely appropriate to use this constructor.
107 * Use {@link #parseBoolean(String)} to convert a string to a
108 * {@code boolean} primitive, or use {@link #valueOf(String)}
109 * to convert a string to a {@code Boolean} object.
110 */
111 @Deprecated(since="9")
112 public Boolean(String s) {
113 this(parseBoolean(s));
114 }
115
116 /**
117 * Parses the string argument as a boolean. The {@code boolean}
118 * returned represents the value {@code true} if the string argument
119 * is not {@code null} and is equal, ignoring case, to the string
120 * {@code "true"}. <p>
121 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
122 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
123 *
124 * @param s the {@code String} containing the boolean
125 * representation to be parsed
126 * @return the boolean represented by the string argument
127 * @since 1.5
128 */
129 public static boolean parseBoolean(String s) {
130 return ((s != null) && s.equalsIgnoreCase("true"));
131 }
132
133 /**
134 * Returns the value of this {@code Boolean} object as a boolean
135 * primitive.
136 *
137 * @return the primitive {@code boolean} value of this object.
138 */
139 @HotSpotIntrinsicCandidate
140 public boolean booleanValue() {
141 return value;
142 }
143
144 /**
145 * Returns a {@code Boolean} instance representing the specified
146 * {@code boolean} value. If the specified {@code boolean} value
147 * is {@code true}, this method returns {@code Boolean.TRUE};
148 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
149 * If a new {@code Boolean} instance is not required, this method
150 * should generally be used in preference to the constructor
151 * {@link #Boolean(boolean)}, as this method is likely to yield
152 * significantly better space and time performance.
153 *
154 * @param b a boolean value.
155 * @return a {@code Boolean} instance representing {@code b}.
156 * @since 1.4
157 */
158 @HotSpotIntrinsicCandidate
159 public static Boolean valueOf(boolean b) {
160 return (b ? TRUE : FALSE);
161 }
162
163 /**
164 * Returns a {@code Boolean} with a value represented by the
165 * specified string. The {@code Boolean} returned represents a
166 * true value if the string argument is not {@code null}
167 * and is equal, ignoring case, to the string {@code "true"}.
168 *
169 * @param s a string.
170 * @return the {@code Boolean} value represented by the string.
171 */
172 public static Boolean valueOf(String s) {
173 return parseBoolean(s) ? TRUE : FALSE;
174 }
175
176 /**
177 * Returns a {@code String} object representing the specified
178 * boolean. If the specified boolean is {@code true}, then
179 * the string {@code "true"} will be returned, otherwise the
180 * string {@code "false"} will be returned.
181 *
182 * @param b the boolean to be converted
183 * @return the string representation of the specified {@code boolean}
184 * @since 1.4
185 */
186 public static String toString(boolean b) {
187 return b ? "true" : "false";
188 }
189
190 /**
191 * Returns a {@code String} object representing this Boolean's
192 * value. If this object represents the value {@code true},
193 * a string equal to {@code "true"} is returned. Otherwise, a
194 * string equal to {@code "false"} is returned.
195 *
196 * @return a string representation of this object.
197 */
198 public String toString() {
199 return value ? "true" : "false";
200 }
201
202 /**
203 * Returns a hash code for this {@code Boolean} object.
204 *
205 * @return the integer {@code 1231} if this object represents
206 * {@code true}; returns the integer {@code 1237} if this
207 * object represents {@code false}.
208 */
209 @Override
210 public int hashCode() {
211 return Boolean.hashCode(value);
212 }
213
214 /**
215 * Returns a hash code for a {@code boolean} value; compatible with
216 * {@code Boolean.hashCode()}.
217 *
218 * @param value the value to hash
219 * @return a hash code value for a {@code boolean} value.
220 * @since 1.8
221 */
222 public static int hashCode(boolean value) {
223 return value ? 1231 : 1237;
224 }
225
226 /**
227 * Returns {@code true} if and only if the argument is not
228 * {@code null} and is a {@code Boolean} object that
229 * represents the same {@code boolean} value as this object.
230 *
231 * @param obj the object to compare with.
232 * @return {@code true} if the Boolean objects represent the
233 * same value; {@code false} otherwise.
234 */
235 public boolean equals(Object obj) {
236 if (obj instanceof Boolean) {
237 return value == ((Boolean)obj).booleanValue();
238 }
239 return false;
240 }
241
242 /**
243 * Returns {@code true} if and only if the system property named
244 * by the argument exists and is equal to the string {@code
245 * "true"}. (Beginning with version 1.0.2 of the Java™
246 * platform, the test of this string is case insensitive.) A
247 * system property is accessible through {@code getProperty}, a
248 * method defined by the {@code System} class.
249 * <p>
250 * If there is no property with the specified name, or if the specified
251 * name is empty or null, then {@code false} is returned.
252 *
253 * @param name the system property name.
254 * @return the {@code boolean} value of the system property.
255 * @throws SecurityException for the same reasons as
256 * {@link System#getProperty(String) System.getProperty}
257 * @see java.lang.System#getProperty(java.lang.String)
258 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
259 */
260 public static boolean getBoolean(String name) {
261 boolean result = false;
262 try {
263 result = parseBoolean(System.getProperty(name));
264 } catch (IllegalArgumentException | NullPointerException e) {
265 }
266 return result;
267 }
268
269 /**
270 * Compares this {@code Boolean} instance with another.
271 *
272 * @param b the {@code Boolean} instance to be compared
273 * @return zero if this object represents the same boolean value as the
274 * argument; a positive value if this object represents true
275 * and the argument represents false; and a negative value if
276 * this object represents false and the argument represents true
277 * @throws NullPointerException if the argument is {@code null}
278 * @see Comparable
279 * @since 1.5
280 */
281 public int compareTo(Boolean b) {
282 return compare(this.value, b.value);
283 }
284
285 /**
286 * Compares two {@code boolean} values.
287 * The value returned is identical to what would be returned by:
288 * <pre>
289 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
290 * </pre>
291 *
292 * @param x the first {@code boolean} to compare
293 * @param y the second {@code boolean} to compare
294 * @return the value {@code 0} if {@code x == y};
295 * a value less than {@code 0} if {@code !x && y}; and
296 * a value greater than {@code 0} if {@code x && !y}
297 * @since 1.7
298 */
299 public static int compare(boolean x, boolean y) {
300 return (x == y) ? 0 : (x ? 1 : -1);
301 }
302
303 /**
304 * Returns the result of applying the logical AND operator to the
305 * specified {@code boolean} operands.
306 *
307 * @param a the first operand
308 * @param b the second operand
309 * @return the logical AND of {@code a} and {@code b}
310 * @see java.util.function.BinaryOperator
311 * @since 1.8
312 */
313 public static boolean logicalAnd(boolean a, boolean b) {
314 return a && b;
315 }
316
317 /**
318 * Returns the result of applying the logical OR operator to the
319 * specified {@code boolean} operands.
320 *
321 * @param a the first operand
322 * @param b the second operand
323 * @return the logical OR of {@code a} and {@code b}
324 * @see java.util.function.BinaryOperator
325 * @since 1.8
326 */
327 public static boolean logicalOr(boolean a, boolean b) {
328 return a || b;
329 }
330
331 /**
332 * Returns the result of applying the logical XOR operator to the
333 * specified {@code boolean} operands.
334 *
335 * @param a the first operand
336 * @param b the second operand
337 * @return the logical XOR of {@code a} and {@code b}
338 * @see java.util.function.BinaryOperator
339 * @since 1.8
340 */
341 public static boolean logicalXor(boolean a, boolean b) {
342 return a ^ b;
343 }
344 }