1 /*
2 * Copyright (c) 1994, 2024, 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.value.DeserializeConstructor;
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, mutexes, 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, mutexes, 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.MigratedValueClass
66 @jdk.internal.ValueBased
67 public final class Boolean implements java.io.Serializable,
68 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", forRemoval = true)
114 public Boolean(boolean value) {
115 this.value = value;
116 }
117
118 /**
119 * Allocates a {@code Boolean} object representing the value
120 * {@code true} if the string argument is not {@code null}
121 * and is equal, ignoring case, to the string {@code "true"}.
122 * Otherwise, allocates a {@code Boolean} object representing the
123 * value {@code false}.
124 *
125 * @param s the string to be converted to a {@code Boolean}.
126 *
127 * @deprecated
128 * It is rarely appropriate to use this constructor.
129 * Use {@link #parseBoolean(String)} to convert a string to a
130 * {@code boolean} primitive, or use {@link #valueOf(String)}
131 * to convert a string to a {@code Boolean} object.
132 */
133 @Deprecated(since="9", forRemoval = true)
134 public Boolean(String s) {
135 this(parseBoolean(s));
136 }
137
138 /**
139 * Parses the string argument as a boolean. The {@code boolean}
140 * returned represents the value {@code true} if the string argument
141 * is not {@code null} and is equal, ignoring case, to the string
142 * {@code "true"}.
143 * Otherwise, a false value is returned, including for a null
144 * argument.<p>
145 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
146 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
147 *
148 * @param s the {@code String} containing the boolean
149 * representation to be parsed
150 * @return the boolean represented by the string argument
151 * @since 1.5
152 */
153 public static boolean parseBoolean(String s) {
154 return "true".equalsIgnoreCase(s);
155 }
156
157 /**
158 * Returns the value of this {@code Boolean} object as a boolean
159 * primitive.
160 *
161 * @return the primitive {@code boolean} value of this object.
162 */
163 @IntrinsicCandidate
164 public boolean booleanValue() {
165 return value;
166 }
167
168 /**
169 * Returns a {@code Boolean} instance representing the specified
170 * {@code boolean} value. If the specified {@code boolean} value
171 * is {@code true}, this method returns {@code Boolean.TRUE};
172 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
173 * If a new {@code Boolean} instance is not required, this method
174 * should generally be used in preference to the constructor
175 * {@link #Boolean(boolean)}, as this method is likely to yield
176 * significantly better space and time performance.
177 *
178 * @param b a boolean value.
179 * @return a {@code Boolean} instance representing {@code b}.
180 * @since 1.4
181 */
182 @IntrinsicCandidate
183 @DeserializeConstructor
184 public static Boolean valueOf(boolean b) {
185 return (b ? TRUE : FALSE);
186 }
187
188 /**
189 * Returns a {@code Boolean} with a value represented by the
190 * specified string. The {@code Boolean} returned represents a
191 * true value if the string argument is not {@code null}
192 * and is equal, ignoring case, to the string {@code "true"}.
193 * Otherwise, a false value is returned, including for a null
194 * argument.
195 *
196 * @param s a string.
197 * @return the {@code Boolean} value represented by the string.
198 */
199 public static Boolean valueOf(String s) {
200 return parseBoolean(s) ? TRUE : FALSE;
201 }
202
203 /**
204 * Returns a {@code String} object representing the specified
205 * boolean. If the specified boolean is {@code true}, then
206 * the string {@code "true"} will be returned, otherwise the
207 * string {@code "false"} will be returned.
208 *
209 * @param b the boolean to be converted
210 * @return the string representation of the specified {@code boolean}
211 * @since 1.4
212 */
213 public static String toString(boolean b) {
214 return String.valueOf(b);
215 }
216
217 /**
218 * Returns a {@code String} object representing this Boolean's
219 * value. If this object represents the value {@code true},
220 * a string equal to {@code "true"} is returned. Otherwise, a
221 * string equal to {@code "false"} is returned.
222 *
223 * @return a string representation of this object.
224 */
225 @Override
226 public String toString() {
227 return String.valueOf(value);
228 }
229
230 /**
231 * Returns a hash code for this {@code Boolean} object.
232 *
233 * @return the integer {@code 1231} if this object represents
234 * {@code true}; returns the integer {@code 1237} if this
235 * object represents {@code false}.
236 */
237 @Override
238 public int hashCode() {
239 return Boolean.hashCode(value);
240 }
241
242 /**
243 * Returns a hash code for a {@code boolean} value; compatible with
244 * {@code Boolean.hashCode()}.
245 *
246 * @param value the value to hash
247 * @return a hash code value for a {@code boolean} value.
248 * @since 1.8
249 */
250 public static int hashCode(boolean value) {
251 return value ? 1231 : 1237;
252 }
253
254 /**
255 * Returns {@code true} if and only if the argument is not
256 * {@code null} and is a {@code Boolean} object that
257 * represents the same {@code boolean} value as this object.
258 *
259 * @param obj the object to compare with.
260 * @return {@code true} if the Boolean objects represent the
261 * same value; {@code false} otherwise.
262 */
263 public boolean equals(Object obj) {
264 if (obj instanceof Boolean b) {
265 return value == b.booleanValue();
266 }
267 return false;
268 }
269
270 /**
271 * Returns {@code true} if and only if the system property named
272 * by the argument exists and is equal to, ignoring case, the
273 * string {@code "true"}.
274 * A system property is accessible through {@code getProperty}, a
275 * method defined by the {@code System} class. <p> If there is no
276 * property with the specified name, or if the specified name is
277 * empty or null, then {@code false} is returned.
278 *
279 * @param name the system property name.
280 * @return the {@code boolean} value of the system property.
281 * @throws SecurityException for the same reasons as
282 * {@link System#getProperty(String) System.getProperty}
283 * @see java.lang.System#getProperty(java.lang.String)
284 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
285 */
286 public static boolean getBoolean(String name) {
287 boolean result = false;
288 try {
289 result = parseBoolean(System.getProperty(name));
290 } catch (IllegalArgumentException | NullPointerException e) {
291 }
292 return result;
293 }
294
295 /**
296 * Compares this {@code Boolean} instance with another.
297 *
298 * @param b the {@code Boolean} instance to be compared
299 * @return zero if this object represents the same boolean value as the
300 * argument; a positive value if this object represents true
301 * and the argument represents false; and a negative value if
302 * this object represents false and the argument represents true
303 * @throws NullPointerException if the argument is {@code null}
304 * @see Comparable
305 * @since 1.5
306 */
307 public int compareTo(Boolean b) {
308 return compare(this.value, b.value);
309 }
310
311 /**
312 * Compares two {@code boolean} values.
313 * The value returned is identical to what would be returned by:
314 * <pre>
315 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
316 * </pre>
317 *
318 * @param x the first {@code boolean} to compare
319 * @param y the second {@code boolean} to compare
320 * @return the value {@code 0} if {@code x == y};
321 * a value less than {@code 0} if {@code !x && y}; and
322 * a value greater than {@code 0} if {@code x && !y}
323 * @since 1.7
324 */
325 public static int compare(boolean x, boolean y) {
326 return (x == y) ? 0 : (x ? 1 : -1);
327 }
328
329 /**
330 * Returns the result of applying the logical AND 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 AND of {@code a} and {@code b}
336 * @see java.util.function.BinaryOperator
337 * @since 1.8
338 */
339 public static boolean logicalAnd(boolean a, boolean b) {
340 return a && b;
341 }
342
343 /**
344 * Returns the result of applying the logical OR operator to the
345 * specified {@code boolean} operands.
346 *
347 * @param a the first operand
348 * @param b the second operand
349 * @return the logical OR of {@code a} and {@code b}
350 * @see java.util.function.BinaryOperator
351 * @since 1.8
352 */
353 public static boolean logicalOr(boolean a, boolean b) {
354 return a || b;
355 }
356
357 /**
358 * Returns the result of applying the logical XOR operator to the
359 * specified {@code boolean} operands.
360 *
361 * @param a the first operand
362 * @param b the second operand
363 * @return the logical XOR of {@code a} and {@code b}
364 * @see java.util.function.BinaryOperator
365 * @since 1.8
366 */
367 public static boolean logicalXor(boolean a, boolean b) {
368 return a ^ b;
369 }
370
371 /**
372 * Returns an {@link Optional} containing the nominal descriptor for this
373 * instance.
374 *
375 * @return an {@link Optional} describing the {@linkplain Boolean} instance
376 * @since 15
377 */
378 @Override
379 public Optional<DynamicConstantDesc<Boolean>> describeConstable() {
380 return Optional.of(value ? ConstantDescs.TRUE : ConstantDescs.FALSE);
381 }
382 }