1 /*
2 * Copyright (c) 1994, 2025, 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.misc.PreviewFeatures;
29 import jdk.internal.value.DeserializeConstructor;
30 import jdk.internal.vm.annotation.IntrinsicCandidate;
31
32 import java.lang.constant.Constable;
33 import java.lang.constant.ConstantDescs;
34 import java.lang.constant.DynamicConstantDesc;
35 import java.util.Optional;
36
37 /**
38 * The {@code Boolean} class is the {@linkplain
39 * java.lang##wrapperClass wrapper class} for values of the primitive
40 * type {@code boolean}. An object of type {@code Boolean} contains a
41 * single field whose type is {@code boolean}.
42 *
43 * <p>In addition, this class provides many methods for
44 * converting a {@code boolean} to a {@code String} and a
45 * {@code String} to a {@code boolean}, as well as other
46 * constants and methods useful when dealing with a
47 * {@code boolean}.
48 *
49 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
50 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
51 * as interchangeable and should not use instances for synchronization, mutexes, or
52 * with {@linkplain java.lang.ref.Reference object references}.
53 *
54 * <div class="preview-block">
55 * <div class="preview-comment">
56 * When preview features are enabled, {@code Boolean} is a {@linkplain Class#isValue value class}.
57 * Use of value class instances for synchronization, mutexes, or with
58 * {@linkplain java.lang.ref.Reference object references} result in
59 * {@link IdentityException}.
60 * </div>
61 * </div>
62 *
63 * @author Arthur van Hoff
64 * @since 1.0
65 */
66 @jdk.internal.MigratedValueClass
67 @jdk.internal.ValueBased
68 public final class Boolean implements java.io.Serializable,
69 Comparable<Boolean>, Constable
70 {
71 /**
72 * The {@code Boolean} object corresponding to the primitive
73 * value {@code true}.
74 */
75 public static final Boolean TRUE = new Boolean(true);
76
77 /**
78 * The {@code Boolean} object corresponding to the primitive
79 * value {@code false}.
80 */
81 public static final Boolean FALSE = new Boolean(false);
82
83 /**
84 * The Class object representing the primitive type boolean.
85 *
86 * @since 1.1
87 */
88 public static final Class<Boolean> TYPE = Class.getPrimitiveClass("boolean");
89
90 /**
91 * The value of the Boolean.
92 *
93 * @serial
94 */
95 private final boolean value;
96
97 /** use serialVersionUID from JDK 1.0.2 for interoperability */
98 @java.io.Serial
99 private static final long serialVersionUID = -3665804199014368530L;
100
101 /**
102 * Allocates a {@code Boolean} object representing the
103 * {@code value} argument.
104 *
105 * @param value the value of the {@code Boolean}.
106 *
107 * @deprecated
108 * It is rarely appropriate to use this constructor. The static factory
109 * {@link #valueOf(boolean)} is generally a better choice, as it is
110 * likely to yield significantly better space and time performance.
111 * Also consider using the final fields {@link #TRUE} and {@link #FALSE}
112 * if possible.
113 */
114 @Deprecated(since="9")
115 public Boolean(boolean value) {
116 this.value = value;
117 }
118
119 /**
120 * Allocates a {@code Boolean} object representing the value
121 * {@code true} if the string argument is not {@code null}
122 * and is equal, ignoring case, to the string {@code "true"}.
123 * Otherwise, allocates a {@code Boolean} object representing the
124 * value {@code false}.
125 *
126 * @param s the string to be converted to a {@code Boolean}.
127 *
128 * @deprecated
129 * It is rarely appropriate to use this constructor.
130 * Use {@link #parseBoolean(String)} to convert a string to a
131 * {@code boolean} primitive, or use {@link #valueOf(String)}
132 * to convert a string to a {@code Boolean} object.
133 */
134 @Deprecated(since="9")
135 public Boolean(String s) {
136 this(parseBoolean(s));
137 }
138
139 /**
140 * Parses the string argument as a boolean. The {@code boolean}
141 * returned represents the value {@code true} if the string argument
142 * is not {@code null} and is equal, ignoring case, to the string
143 * {@code "true"}.
144 * Otherwise, a false value is returned, including for a null
145 * argument.<p>
146 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
147 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
148 *
149 * @param s the {@code String} containing the boolean
150 * representation to be parsed
151 * @return the boolean represented by the string argument
152 * @since 1.5
153 */
154 public static boolean parseBoolean(String s) {
155 return "true".equalsIgnoreCase(s);
156 }
157
158 /**
159 * Returns the value of this {@code Boolean} object as a boolean
160 * primitive.
161 *
162 * @return the primitive {@code boolean} value of this object.
163 */
164 @IntrinsicCandidate
165 public boolean booleanValue() {
166 return value;
167 }
168
169 /**
170 * Returns a {@code Boolean} instance representing the specified
171 * {@code boolean} value. If the specified {@code boolean} value
172 * is {@code true}, this method returns {@code Boolean.TRUE};
173 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
174 * If a new {@code Boolean} instance is not required, this method
175 * should generally be used in preference to the constructor
176 * {@link #Boolean(boolean)}, as this method is likely to yield
177 * significantly better space and time performance.
178 *
179 * @param b a boolean value.
180 * @return a {@code Boolean} instance representing {@code b}.
181 * @since 1.4
182 */
183 @IntrinsicCandidate
184 @DeserializeConstructor
185 public static Boolean valueOf(boolean b) {
186 if (!PreviewFeatures.isEnabled()) {
187 return (b ? TRUE : FALSE);
188 }
189 return new Boolean(b);
190 }
191
192 /**
193 * Returns a {@code Boolean} with a value represented by the
194 * specified string. The {@code Boolean} returned represents a
195 * true value if the string argument is not {@code null}
196 * and is equal, ignoring case, to the string {@code "true"}.
197 * Otherwise, a false value is returned, including for a null
198 * argument.
199 *
200 * @param s a string.
201 * @return the {@code Boolean} value represented by the string.
202 */
203 public static Boolean valueOf(String s) {
204 return parseBoolean(s) ? TRUE : FALSE;
205 }
206
207 /**
208 * Returns a {@code String} object representing the specified
209 * boolean. If the specified boolean is {@code true}, then
210 * the string {@code "true"} will be returned, otherwise the
211 * string {@code "false"} will be returned.
212 *
213 * @param b the boolean to be converted
214 * @return the string representation of the specified {@code boolean}
215 * @since 1.4
216 */
217 public static String toString(boolean b) {
218 return String.valueOf(b);
219 }
220
221 /**
222 * Returns a {@code String} object representing this Boolean's
223 * value. If this object represents the value {@code true},
224 * a string equal to {@code "true"} is returned. Otherwise, a
225 * string equal to {@code "false"} is returned.
226 *
227 * @return a string representation of this object.
228 */
229 @Override
230 public String toString() {
231 return String.valueOf(value);
232 }
233
234 /**
235 * Returns a hash code for this {@code Boolean} object.
236 *
237 * @return the integer {@code 1231} if this object represents
238 * {@code true}; returns the integer {@code 1237} if this
239 * object represents {@code false}.
240 */
241 @Override
242 public int hashCode() {
243 return Boolean.hashCode(value);
244 }
245
246 /**
247 * Returns a hash code for a {@code boolean} value; compatible with
248 * {@code Boolean.hashCode()}.
249 *
250 * @param value the value to hash
251 * @return a hash code value for a {@code boolean} value.
252 * @since 1.8
253 */
254 public static int hashCode(boolean value) {
255 return value ? 1231 : 1237;
256 }
257
258 /**
259 * Returns {@code true} if and only if the argument is not
260 * {@code null} and is a {@code Boolean} object that
261 * represents the same {@code boolean} value as this object.
262 *
263 * @param obj the object to compare with.
264 * @return {@code true} if the Boolean objects represent the
265 * same value; {@code false} otherwise.
266 */
267 public boolean equals(Object obj) {
268 if (obj instanceof Boolean b) {
269 return value == b.booleanValue();
270 }
271 return false;
272 }
273
274 /**
275 * Returns {@code true} if and only if the system property named
276 * by the argument exists and is equal to, ignoring case, the
277 * string {@code "true"}.
278 * A system property is accessible through {@code getProperty}, a
279 * method defined by the {@code System} class. <p> If there is no
280 * property with the specified name, or if the specified name is
281 * empty or null, then {@code false} is returned.
282 *
283 * @param name the system property name.
284 * @return the {@code boolean} value of the system property.
285 * @see java.lang.System#getProperty(java.lang.String)
286 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
287 */
288 public static boolean getBoolean(String name) {
289 return name != null && !name.isEmpty() && parseBoolean(System.getProperty(name));
290 }
291
292 /**
293 * Compares this {@code Boolean} instance with another.
294 *
295 * @param b the {@code Boolean} instance to be compared
296 * @return zero if this object represents the same boolean value as the
297 * argument; a positive value if this object represents true
298 * and the argument represents false; and a negative value if
299 * this object represents false and the argument represents true
300 * @throws NullPointerException if the argument is {@code null}
301 * @see Comparable
302 * @since 1.5
303 */
304 public int compareTo(Boolean b) {
305 return compare(this.value, b.value);
306 }
307
308 /**
309 * Compares two {@code boolean} values.
310 * The value returned is identical to what would be returned by:
311 * <pre>
312 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
313 * </pre>
314 *
315 * @param x the first {@code boolean} to compare
316 * @param y the second {@code boolean} to compare
317 * @return the value {@code 0} if {@code x == y};
318 * a value less than {@code 0} if {@code !x && y}; and
319 * a value greater than {@code 0} if {@code x && !y}
320 * @since 1.7
321 */
322 public static int compare(boolean x, boolean y) {
323 return (x == y) ? 0 : (x ? 1 : -1);
324 }
325
326 /**
327 * Returns the result of applying the logical AND operator to the
328 * specified {@code boolean} operands.
329 *
330 * @param a the first operand
331 * @param b the second operand
332 * @return the logical AND of {@code a} and {@code b}
333 * @see java.util.function.BinaryOperator
334 * @since 1.8
335 */
336 public static boolean logicalAnd(boolean a, boolean b) {
337 return a && b;
338 }
339
340 /**
341 * Returns the result of applying the logical OR operator to the
342 * specified {@code boolean} operands.
343 *
344 * @param a the first operand
345 * @param b the second operand
346 * @return the logical OR of {@code a} and {@code b}
347 * @see java.util.function.BinaryOperator
348 * @since 1.8
349 */
350 public static boolean logicalOr(boolean a, boolean b) {
351 return a || b;
352 }
353
354 /**
355 * Returns the result of applying the logical XOR operator to the
356 * specified {@code boolean} operands.
357 *
358 * @param a the first operand
359 * @param b the second operand
360 * @return the logical XOR of {@code a} and {@code b}
361 * @see java.util.function.BinaryOperator
362 * @since 1.8
363 */
364 public static boolean logicalXor(boolean a, boolean b) {
365 return a ^ b;
366 }
367
368 /**
369 * Returns an {@link Optional} containing the nominal descriptor for this
370 * instance.
371 *
372 * @return an {@link Optional} describing the {@linkplain Boolean} instance
373 * @since 15
374 */
375 @Override
376 public Optional<DynamicConstantDesc<Boolean>> describeConstable() {
377 return Optional.of(value ? ConstantDescs.TRUE : ConstantDescs.FALSE);
378 }
379 }