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.vm.annotation.IntrinsicCandidate;
29
30 import java.lang.constant.Constable;
31 import java.lang.constant.ConstantDesc;
32 import java.lang.constant.ConstantDescs;
33 import java.lang.constant.DynamicConstantDesc;
34 import java.util.Optional;
35
36 import static java.lang.constant.ConstantDescs.BSM_GET_STATIC_FINAL;
37 import static java.lang.constant.ConstantDescs.CD_Boolean;
38
39 /**
40 * The {@code Boolean} class is the {@linkplain
41 * java.lang##wrapperClass wrapper class} for values of the primitive
42 * type {@code boolean}. An object of type {@code Boolean} contains a
43 * single field whose type is {@code boolean}.
44 *
45 * <p>In addition, this class provides many methods for
46 * converting a {@code boolean} to a {@code String} and a
47 * {@code String} to a {@code boolean}, as well as other
48 * constants and methods useful when dealing with a
49 * {@code boolean}.
50 *
51 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
52 * class; programmers should treat instances that are
53 * {@linkplain #equals(Object) equal} as interchangeable and should not
54 * use instances for synchronization, or unpredictable behavior may
55 * occur. For example, in a future release, synchronization may fail.
56 *
57 * @author Arthur van Hoff
58 * @since 1.0
59 */
60 @jdk.internal.ValueBased
61 public final class Boolean implements java.io.Serializable,
62 Comparable<Boolean>, Constable
63 {
64 // AOT cache support - there are references to these fields by other cached Java objects. We need
65 // to preserve their identity across AOT cache assembly phase and production runs.
66 static class AOTHolder {
67 private static final Boolean TRUE = new Boolean(true);
68 private static final Boolean FALSE = new Boolean(false);
69 }
70
71 /**
72 * The {@code Boolean} object corresponding to the primitive
73 * value {@code true}.
74 */
75 public static final Boolean TRUE = AOTHolder.TRUE;
76
77 /**
78 * The {@code Boolean} object corresponding to the primitive
79 * value {@code false}.
80 */
81 public static final Boolean FALSE = AOTHolder.FALSE;
82
83 /**
84 * The Class object representing the primitive type boolean.
85 *
86 * @since 1.1
87 */
88 @SuppressWarnings("unchecked")
89 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");
90
91 /**
92 * The value of the Boolean.
93 *
94 * @serial
95 */
96 private final boolean value;
97
98 /** use serialVersionUID from JDK 1.0.2 for interoperability */
99 @java.io.Serial
100 private static final long serialVersionUID = -3665804199014368530L;
101
102 /**
103 * Allocates a {@code Boolean} object representing the
104 * {@code value} argument.
105 *
106 * @param value the value of the {@code Boolean}.
107 *
108 * @deprecated
109 * It is rarely appropriate to use this constructor. The static factory
110 * {@link #valueOf(boolean)} is generally a better choice, as it is
111 * likely to yield significantly better space and time performance.
112 * Also consider using the final fields {@link #TRUE} and {@link #FALSE}
113 * if possible.
114 */
115 @Deprecated(since="9", forRemoval = true)
116 public Boolean(boolean value) {
117 this.value = value;
118 }
119
120 /**
121 * Allocates a {@code Boolean} object representing the value
122 * {@code true} if the string argument is not {@code null}
123 * and is equal, ignoring case, to the string {@code "true"}.
124 * Otherwise, allocates a {@code Boolean} object representing the
125 * value {@code false}.
126 *
127 * @param s the string to be converted to a {@code Boolean}.
128 *
129 * @deprecated
130 * It is rarely appropriate to use this constructor.
131 * Use {@link #parseBoolean(String)} to convert a string to a
132 * {@code boolean} primitive, or use {@link #valueOf(String)}
133 * to convert a string to a {@code Boolean} object.
134 */
135 @Deprecated(since="9", forRemoval = true)
136 public Boolean(String s) {
137 this(parseBoolean(s));
138 }
139
140 /**
141 * Parses the string argument as a boolean. The {@code boolean}
142 * returned represents the value {@code true} if the string argument
143 * is not {@code null} and is equal, ignoring case, to the string
144 * {@code "true"}.
145 * Otherwise, a false value is returned, including for a null
146 * argument.<p>
147 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
148 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
149 *
150 * @param s the {@code String} containing the boolean
151 * representation to be parsed
152 * @return the boolean represented by the string argument
153 * @since 1.5
154 */
155 public static boolean parseBoolean(String s) {
156 return "true".equalsIgnoreCase(s);
157 }
158
159 /**
160 * Returns the value of this {@code Boolean} object as a boolean
161 * primitive.
162 *
163 * @return the primitive {@code boolean} value of this object.
164 */
165 @IntrinsicCandidate
166 public boolean booleanValue() {
167 return value;
168 }
169
170 /**
171 * Returns a {@code Boolean} instance representing the specified
172 * {@code boolean} value. If the specified {@code boolean} value
173 * is {@code true}, this method returns {@code Boolean.TRUE};
174 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
175 * If a new {@code Boolean} instance is not required, this method
176 * should generally be used in preference to the constructor
177 * {@link #Boolean(boolean)}, as this method is likely to yield
178 * significantly better space and time performance.
179 *
180 * @param b a boolean value.
181 * @return a {@code Boolean} instance representing {@code b}.
182 * @since 1.4
183 */
184 @IntrinsicCandidate
185 public static Boolean valueOf(boolean b) {
186 return (b ? TRUE : FALSE);
187 }
188
189 /**
190 * Returns a {@code Boolean} with a value represented by the
191 * specified string. The {@code Boolean} returned represents a
192 * true value if the string argument is not {@code null}
193 * and is equal, ignoring case, to the string {@code "true"}.
194 * Otherwise, a false value is returned, including for a null
195 * argument.
196 *
197 * @param s a string.
198 * @return the {@code Boolean} value represented by the string.
199 */
200 public static Boolean valueOf(String s) {
201 return parseBoolean(s) ? TRUE : FALSE;
202 }
203
204 /**
205 * Returns a {@code String} object representing the specified
206 * boolean. If the specified boolean is {@code true}, then
207 * the string {@code "true"} will be returned, otherwise the
208 * string {@code "false"} will be returned.
209 *
210 * @param b the boolean to be converted
211 * @return the string representation of the specified {@code boolean}
212 * @since 1.4
213 */
214 public static String toString(boolean b) {
215 return String.valueOf(b);
216 }
217
218 /**
219 * Returns a {@code String} object representing this Boolean's
220 * value. If this object represents the value {@code true},
221 * a string equal to {@code "true"} is returned. Otherwise, a
222 * string equal to {@code "false"} is returned.
223 *
224 * @return a string representation of this object.
225 */
226 @Override
227 public String toString() {
228 return String.valueOf(value);
229 }
230
231 /**
232 * Returns a hash code for this {@code Boolean} object.
233 *
234 * @return the integer {@code 1231} if this object represents
235 * {@code true}; returns the integer {@code 1237} if this
236 * object represents {@code false}.
237 */
238 @Override
239 public int hashCode() {
240 return Boolean.hashCode(value);
241 }
242
243 /**
244 * Returns a hash code for a {@code boolean} value; compatible with
245 * {@code Boolean.hashCode()}.
246 *
247 * @param value the value to hash
248 * @return a hash code value for a {@code boolean} value.
249 * @since 1.8
250 */
251 public static int hashCode(boolean value) {
252 return value ? 1231 : 1237;
253 }
254
255 /**
256 * Returns {@code true} if and only if the argument is not
257 * {@code null} and is a {@code Boolean} object that
258 * represents the same {@code boolean} value as this object.
259 *
260 * @param obj the object to compare with.
261 * @return {@code true} if the Boolean objects represent the
262 * same value; {@code false} otherwise.
263 */
264 public boolean equals(Object obj) {
265 if (obj instanceof Boolean) {
266 return value == ((Boolean)obj).booleanValue();
267 }
268 return false;
269 }
270
271 /**
272 * Returns {@code true} if and only if the system property named
273 * by the argument exists and is equal to, ignoring case, the
274 * string {@code "true"}.
275 * A system property is accessible through {@code getProperty}, a
276 * method defined by the {@code System} class. <p> If there is no
277 * property with the specified name, or if the specified name is
278 * empty or null, then {@code false} is returned.
279 *
280 * @param name the system property name.
281 * @return the {@code boolean} value of the system property.
282 * @throws SecurityException for the same reasons as
283 * {@link System#getProperty(String) System.getProperty}
284 * @see java.lang.System#getProperty(java.lang.String)
285 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
286 */
287 public static boolean getBoolean(String name) {
288 boolean result = false;
289 try {
290 result = parseBoolean(System.getProperty(name));
291 } catch (IllegalArgumentException | NullPointerException e) {
292 }
293 return result;
294 }
295
296 /**
297 * Compares this {@code Boolean} instance with another.
298 *
299 * @param b the {@code Boolean} instance to be compared
300 * @return zero if this object represents the same boolean value as the
301 * argument; a positive value if this object represents true
302 * and the argument represents false; and a negative value if
303 * this object represents false and the argument represents true
304 * @throws NullPointerException if the argument is {@code null}
305 * @see Comparable
306 * @since 1.5
307 */
308 public int compareTo(Boolean b) {
309 return compare(this.value, b.value);
310 }
311
312 /**
313 * Compares two {@code boolean} values.
314 * The value returned is identical to what would be returned by:
315 * <pre>
316 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
317 * </pre>
318 *
319 * @param x the first {@code boolean} to compare
320 * @param y the second {@code boolean} to compare
321 * @return the value {@code 0} if {@code x == y};
322 * a value less than {@code 0} if {@code !x && y}; and
323 * a value greater than {@code 0} if {@code x && !y}
324 * @since 1.7
325 */
326 public static int compare(boolean x, boolean y) {
327 return (x == y) ? 0 : (x ? 1 : -1);
328 }
329
330 /**
331 * Returns the result of applying the logical AND operator to the
332 * specified {@code boolean} operands.
333 *
334 * @param a the first operand
335 * @param b the second operand
336 * @return the logical AND of {@code a} and {@code b}
337 * @see java.util.function.BinaryOperator
338 * @since 1.8
339 */
340 public static boolean logicalAnd(boolean a, boolean b) {
341 return a && b;
342 }
343
344 /**
345 * Returns the result of applying the logical OR operator to the
346 * specified {@code boolean} operands.
347 *
348 * @param a the first operand
349 * @param b the second operand
350 * @return the logical OR of {@code a} and {@code b}
351 * @see java.util.function.BinaryOperator
352 * @since 1.8
353 */
354 public static boolean logicalOr(boolean a, boolean b) {
355 return a || b;
356 }
357
358 /**
359 * Returns the result of applying the logical XOR operator to the
360 * specified {@code boolean} operands.
361 *
362 * @param a the first operand
363 * @param b the second operand
364 * @return the logical XOR of {@code a} and {@code b}
365 * @see java.util.function.BinaryOperator
366 * @since 1.8
367 */
368 public static boolean logicalXor(boolean a, boolean b) {
369 return a ^ b;
370 }
371
372 /**
373 * Returns an {@link Optional} containing the nominal descriptor for this
374 * instance.
375 *
376 * @return an {@link Optional} describing the {@linkplain Boolean} instance
377 * @since 15
378 */
379 @Override
380 public Optional<DynamicConstantDesc<Boolean>> describeConstable() {
381 return Optional.of(value ? ConstantDescs.TRUE : ConstantDescs.FALSE);
382 }
383 }