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