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