1 /*
2 * Copyright (c) 1994, 2026, 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
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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
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23 * questions.
24 */
25
26 package java.lang;
27
28 import jdk.internal.value.Deserializer;
29 import jdk.internal.vm.annotation.IntrinsicCandidate;
30
31 import java.lang.constant.Constable;
32 import java.lang.constant.ConstantDescs;
33 import java.lang.constant.DynamicConstantDesc;
34 import java.util.Optional;
35
36 /**
37 * The {@code Boolean} class is the {@linkplain
38 * java.lang##wrapperClass wrapper class} for values of the primitive
39 * type {@code boolean}. An object of type {@code Boolean} contains a
40 * single field whose type is {@code boolean}.
41 *
42 * <p>In addition, this class provides many methods for
43 * converting a {@code boolean} to a {@code String} and a
44 * {@code String} to a {@code boolean}, as well as other
45 * constants and methods useful when dealing with a
46 * {@code boolean}.
47 *
48 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
49 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
50 * as interchangeable and should not use instances for synchronization or
51 * with {@linkplain java.lang.ref.Reference object references}.
52 *
53 * <div class="preview-block">
54 * <div class="preview-comment">
55 * When preview features are enabled, {@code Boolean} is a {@linkplain Class#isValue value class}.
56 * Use of value class instances for synchronization or with
57 * {@linkplain java.lang.ref.Reference object references} result in
58 * {@link IdentityException}.
59 * </div>
60 * </div>
61 *
62 * @author Arthur van Hoff
63 * @since 1.0
64 */
65 @jdk.internal.ValueBased
66 // See doc/value-class-preview.md for an overview of value class generation
67 public final /*value*/ class Boolean
68 implements java.io.Serializable, Comparable<Boolean>, Constable
69 {
70 /**
71 * The {@code Boolean} object corresponding to the primitive
72 * value {@code true}.
73 */
74 public static final Boolean TRUE = new Boolean(true);
75
76 /**
77 * The {@code Boolean} object corresponding to the primitive
78 * value {@code false}.
79 */
80 public static final Boolean FALSE = new Boolean(false);
81
82 /**
83 * The Class object representing the primitive type boolean.
84 *
85 * @since 1.1
86 */
87 public static final Class<Boolean> TYPE = Class.getPrimitiveClass("boolean");
88
89 /**
90 * The value of the Boolean.
91 *
92 * @serial
93 */
94 private final boolean value;
95
96 /** use serialVersionUID from JDK 1.0.2 for interoperability */
97 @java.io.Serial
98 private static final long serialVersionUID = -3665804199014368530L;
99
100 /**
101 * Allocates a {@code Boolean} object representing the
102 * {@code value} argument.
103 *
104 * @param value the value of the {@code Boolean}.
105 *
106 * @deprecated
107 * It is rarely appropriate to use this constructor. The static factory
108 * {@link #valueOf(boolean)} is generally a better choice, as it is
109 * likely to yield significantly better space and time performance.
110 * Also consider using the final fields {@link #TRUE} and {@link #FALSE}
111 * if possible.
112 */
113 @Deprecated(since="9")
114 @Deserializer("value")
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.
172 * <div class="preview-block">
173 * <div class="preview-comment">
174 * <p>
175 * - When preview features are NOT enabled, {@code Boolean} is an identity class.
176 * If the specified {@code boolean} value is {@code true},
177 * this method returns {@code Boolean.TRUE}; if it is
178 * {@code false}, this method returns {@code Boolean.FALSE}.
179 * If a new {@code Boolean} instance is not required, this
180 * method should generally be used in preference to the
181 * constructor {@link #Boolean(boolean)}, as this method is
182 * likely to yield significantly better space and time
183 * performance.
184 * </p>
185 * <p>
186 * - When preview features are enabled, {@code Boolean} is a {@linkplain Class#isValue value class}.
187 * The {@code valueOf} behavior is the same as invoking the constructor.
188 * </p>
189 * </div>
190 * </div>
191 *
192 * @param b a boolean value.
193 * @return a {@code Boolean} instance representing {@code b}.
194 * @since 1.4
195 */
196 @IntrinsicCandidate
197 public static Boolean valueOf(boolean b) {
198 return (b ? TRUE : FALSE);
199 }
200
201 /**
202 * Returns a {@code Boolean} with a value represented by the
203 * specified string. The {@code Boolean} returned represents a
204 * true value if the string argument is not {@code null}
205 * and is equal, ignoring case, to the string {@code "true"}.
206 * Otherwise, a false value is returned, including for a null
207 * argument.
208 *
209 * @param s a string.
210 * @return the {@code Boolean} value represented by the string.
211 */
212 public static Boolean valueOf(String s) {
213 return parseBoolean(s) ? TRUE : FALSE;
214 }
215
216 /**
217 * Returns a {@code String} object representing the specified
218 * boolean. If the specified boolean is {@code true}, then
219 * the string {@code "true"} will be returned, otherwise the
220 * string {@code "false"} will be returned.
221 *
222 * @param b the boolean to be converted
223 * @return the string representation of the specified {@code boolean}
224 * @since 1.4
225 */
226 public static String toString(boolean b) {
227 return String.valueOf(b);
228 }
229
230 /**
231 * Returns a {@code String} object representing this Boolean's
232 * value. If this object represents the value {@code true},
233 * a string equal to {@code "true"} is returned. Otherwise, a
234 * string equal to {@code "false"} is returned.
235 *
236 * @return a string representation of this object.
237 */
238 @Override
239 public String toString() {
240 return String.valueOf(value);
241 }
242
243 /**
244 * Returns a hash code for this {@code Boolean} object.
245 *
246 * @return the integer {@code 1231} if this object represents
247 * {@code true}; returns the integer {@code 1237} if this
248 * object represents {@code false}.
249 */
250 @Override
251 public int hashCode() {
252 return Boolean.hashCode(value);
253 }
254
255 /**
256 * Returns a hash code for a {@code boolean} value; compatible with
257 * {@code Boolean.hashCode()}.
258 *
259 * @param value the value to hash
260 * @return a hash code value for a {@code boolean} value.
261 * @since 1.8
262 */
263 public static int hashCode(boolean value) {
264 return value ? 1231 : 1237;
265 }
266
267 /**
268 * Returns {@code true} if and only if the argument is not
269 * {@code null} and is a {@code Boolean} object that
270 * represents the same {@code boolean} value as this object.
271 *
272 * @param obj the object to compare with.
273 * @return {@code true} if the Boolean objects represent the
274 * same value; {@code false} otherwise.
275 */
276 public boolean equals(Object obj) {
277 if (obj instanceof Boolean b) {
278 return value == b.booleanValue();
279 }
280 return false;
281 }
282
283 /**
284 * Returns {@code true} if and only if the system property named
285 * by the argument exists and is equal to, ignoring case, the
286 * string {@code "true"}.
287 * A system property is accessible through {@code getProperty}, a
288 * method defined by the {@code System} class. <p> If there is no
289 * property with the specified name, or if the specified name is
290 * empty or null, then {@code false} is returned.
291 *
292 * @param name the system property name.
293 * @return the {@code boolean} value of the system property.
294 * @see java.lang.System#getProperty(java.lang.String)
295 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
296 */
297 public static boolean getBoolean(String name) {
298 return name != null && !name.isEmpty() && parseBoolean(System.getProperty(name));
299 }
300
301 /**
302 * Compares this {@code Boolean} instance with another.
303 *
304 * @param b the {@code Boolean} instance to be compared
305 * @return zero if this object represents the same boolean value as the
306 * argument; a positive value if this object represents true
307 * and the argument represents false; and a negative value if
308 * this object represents false and the argument represents true
309 * @throws NullPointerException if the argument is {@code null}
310 * @see Comparable
311 * @since 1.5
312 */
313 public int compareTo(Boolean b) {
314 return compare(this.value, b.value);
315 }
316
317 /**
318 * Compares two {@code boolean} values.
319 * The value returned is identical to what would be returned by:
320 * <pre>
321 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
322 * </pre>
323 *
324 * @param x the first {@code boolean} to compare
325 * @param y the second {@code boolean} to compare
326 * @return the value {@code 0} if {@code x == y};
327 * a value less than {@code 0} if {@code !x && y}; and
328 * a value greater than {@code 0} if {@code x && !y}
329 * @since 1.7
330 */
331 public static int compare(boolean x, boolean y) {
332 return (x == y) ? 0 : (x ? 1 : -1);
333 }
334
335 /**
336 * Returns the result of applying the logical AND operator to the
337 * specified {@code boolean} operands.
338 *
339 * @param a the first operand
340 * @param b the second operand
341 * @return the logical AND of {@code a} and {@code b}
342 * @see java.util.function.BinaryOperator
343 * @since 1.8
344 */
345 public static boolean logicalAnd(boolean a, boolean b) {
346 return a && b;
347 }
348
349 /**
350 * Returns the result of applying the logical OR operator to the
351 * specified {@code boolean} operands.
352 *
353 * @param a the first operand
354 * @param b the second operand
355 * @return the logical OR of {@code a} and {@code b}
356 * @see java.util.function.BinaryOperator
357 * @since 1.8
358 */
359 public static boolean logicalOr(boolean a, boolean b) {
360 return a || b;
361 }
362
363 /**
364 * Returns the result of applying the logical XOR operator to the
365 * specified {@code boolean} operands.
366 *
367 * @param a the first operand
368 * @param b the second operand
369 * @return the logical XOR of {@code a} and {@code b}
370 * @see java.util.function.BinaryOperator
371 * @since 1.8
372 */
373 public static boolean logicalXor(boolean a, boolean b) {
374 return a ^ b;
375 }
376
377 /**
378 * Returns an {@link Optional} containing the nominal descriptor for this
379 * instance.
380 *
381 * @return an {@link Optional} describing the {@linkplain Boolean} instance
382 * @since 15
383 */
384 @Override
385 public Optional<DynamicConstantDesc<Boolean>> describeConstable() {
386 return Optional.of(value ? ConstantDescs.TRUE : ConstantDescs.FALSE);
387 }
388 }