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 import jdk.internal.misc.CDS;
40
41 /**
42 * The Boolean class wraps a value of the primitive type
43 * {@code boolean} in an object. An object of type
44 * {@code Boolean} contains a single field whose type is
45 * {@code boolean}.
46 *
47 * <p>In addition, this class provides many methods for
48 * converting a {@code boolean} to a {@code String} and a
49 * {@code String} to a {@code boolean}, as well as other
50 * constants and methods useful when dealing with a
51 * {@code boolean}.
52 *
53 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
54 * class; programmers should treat instances that are
55 * {@linkplain #equals(Object) equal} as interchangeable and should not
56 * use instances for synchronization, or unpredictable behavior may
57 * occur. For example, in a future release, synchronization may fail.
58 *
59 * @author Arthur van Hoff
60 * @since 1.0
61 */
62 @jdk.internal.ValueBased
63 public final class Boolean implements java.io.Serializable,
64 Comparable<Boolean>, Constable
65 {
66 // CDS support.
67 private static Boolean[] archivedCache;
68 static {
69 CDS.initializeFromArchive(Boolean.class);
70 }
71
72 /**
73 * The {@code Boolean} object corresponding to the primitive
74 * value {@code true}.
75 */
76 public static final Boolean TRUE = (archivedCache != null) ? archivedCache[0] : new Boolean(true);
77
78 /**
79 * The {@code Boolean} object corresponding to the primitive
80 * value {@code false}.
81 */
82 public static final Boolean FALSE = (archivedCache != null) ? archivedCache[1] : new Boolean(false);
83
84 static {
85 if (archivedCache == null) {
86 archivedCache = new Boolean[2];
87 archivedCache[0] = TRUE;
88 archivedCache[1] = FALSE;
89 }
90 }
91
92 /**
93 * The Class object representing the primitive type boolean.
94 *
95 * @since 1.1
96 */
97 @SuppressWarnings("unchecked")
98 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");
99
100 /**
101 * The value of the Boolean.
102 *
103 * @serial
104 */
105 private final boolean value;
106
107 /** use serialVersionUID from JDK 1.0.2 for interoperability */
108 @java.io.Serial
109 private static final long serialVersionUID = -3665804199014368530L;
110
111 /**
112 * Allocates a {@code Boolean} object representing the
113 * {@code value} argument.
114 *
115 * @param value the value of the {@code Boolean}.
116 *
117 * @deprecated
118 * It is rarely appropriate to use this constructor. The static factory
119 * {@link #valueOf(boolean)} is generally a better choice, as it is
120 * likely to yield significantly better space and time performance.
121 * Also consider using the final fields {@link #TRUE} and {@link #FALSE}
122 * if possible.
123 */
124 @Deprecated(since="9", forRemoval = true)
125 public Boolean(boolean value) {
126 this.value = value;
127 }
128
129 /**
130 * Allocates a {@code Boolean} object representing the value
131 * {@code true} if the string argument is not {@code null}
132 * and is equal, ignoring case, to the string {@code "true"}.
133 * Otherwise, allocates a {@code Boolean} object representing the
134 * value {@code false}.
135 *
136 * @param s the string to be converted to a {@code Boolean}.
137 *
138 * @deprecated
139 * It is rarely appropriate to use this constructor.
140 * Use {@link #parseBoolean(String)} to convert a string to a
141 * {@code boolean} primitive, or use {@link #valueOf(String)}
142 * to convert a string to a {@code Boolean} object.
143 */
144 @Deprecated(since="9", forRemoval = true)
145 public Boolean(String s) {
146 this(parseBoolean(s));
147 }
148
149 /**
150 * Parses the string argument as a boolean. The {@code boolean}
151 * returned represents the value {@code true} if the string argument
152 * is not {@code null} and is equal, ignoring case, to the string
153 * {@code "true"}.
154 * Otherwise, a false value is returned, including for a null
155 * argument.<p>
156 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
157 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
158 *
159 * @param s the {@code String} containing the boolean
160 * representation to be parsed
161 * @return the boolean represented by the string argument
162 * @since 1.5
163 */
164 public static boolean parseBoolean(String s) {
165 return "true".equalsIgnoreCase(s);
166 }
167
168 /**
169 * Returns the value of this {@code Boolean} object as a boolean
170 * primitive.
171 *
172 * @return the primitive {@code boolean} value of this object.
173 */
174 @IntrinsicCandidate
175 public boolean booleanValue() {
176 return value;
177 }
178
179 /**
180 * Returns a {@code Boolean} instance representing the specified
181 * {@code boolean} value. If the specified {@code boolean} value
182 * is {@code true}, this method returns {@code Boolean.TRUE};
183 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
184 * If a new {@code Boolean} instance is not required, this method
185 * should generally be used in preference to the constructor
186 * {@link #Boolean(boolean)}, as this method is likely to yield
187 * significantly better space and time performance.
188 *
189 * @param b a boolean value.
190 * @return a {@code Boolean} instance representing {@code b}.
191 * @since 1.4
192 */
193 @IntrinsicCandidate
194 public static Boolean valueOf(boolean b) {
195 return (b ? TRUE : FALSE);
196 }
197
198 /**
199 * Returns a {@code Boolean} with a value represented by the
200 * specified string. The {@code Boolean} returned represents a
201 * true value if the string argument is not {@code null}
202 * and is equal, ignoring case, to the string {@code "true"}.
203 * Otherwise, a false value is returned, including for a null
204 * argument.
205 *
206 * @param s a string.
207 * @return the {@code Boolean} value represented by the string.
208 */
209 public static Boolean valueOf(String s) {
210 return parseBoolean(s) ? TRUE : FALSE;
211 }
212
213 /**
214 * Returns a {@code String} object representing the specified
215 * boolean. If the specified boolean is {@code true}, then
216 * the string {@code "true"} will be returned, otherwise the
217 * string {@code "false"} will be returned.
218 *
219 * @param b the boolean to be converted
220 * @return the string representation of the specified {@code boolean}
221 * @since 1.4
222 */
223 public static String toString(boolean b) {
224 return String.valueOf(b);
225 }
226
227 /**
228 * Returns a {@code String} object representing this Boolean's
229 * value. If this object represents the value {@code true},
230 * a string equal to {@code "true"} is returned. Otherwise, a
231 * string equal to {@code "false"} is returned.
232 *
233 * @return a string representation of this object.
234 */
235 @Override
236 public String toString() {
237 return String.valueOf(value);
238 }
239
240 /**
241 * Returns a hash code for this {@code Boolean} object.
242 *
243 * @return the integer {@code 1231} if this object represents
244 * {@code true}; returns the integer {@code 1237} if this
245 * object represents {@code false}.
246 */
247 @Override
248 public int hashCode() {
249 return Boolean.hashCode(value);
250 }
251
252 /**
253 * Returns a hash code for a {@code boolean} value; compatible with
254 * {@code Boolean.hashCode()}.
255 *
256 * @param value the value to hash
257 * @return a hash code value for a {@code boolean} value.
258 * @since 1.8
259 */
260 public static int hashCode(boolean value) {
261 return value ? 1231 : 1237;
262 }
263
264 /**
265 * Returns {@code true} if and only if the argument is not
266 * {@code null} and is a {@code Boolean} object that
267 * represents the same {@code boolean} value as this object.
268 *
269 * @param obj the object to compare with.
270 * @return {@code true} if the Boolean objects represent the
271 * same value; {@code false} otherwise.
272 */
273 public boolean equals(Object obj) {
274 if (obj instanceof Boolean) {
275 return value == ((Boolean)obj).booleanValue();
276 }
277 return false;
278 }
279
280 /**
281 * Returns {@code true} if and only if the system property named
282 * by the argument exists and is equal to, ignoring case, the
283 * string {@code "true"}.
284 * A system property is accessible through {@code getProperty}, a
285 * method defined by the {@code System} class. <p> If there is no
286 * property with the specified name, or if the specified name is
287 * empty or null, then {@code false} is returned.
288 *
289 * @param name the system property name.
290 * @return the {@code boolean} value of the system property.
291 * @throws SecurityException for the same reasons as
292 * {@link System#getProperty(String) System.getProperty}
293 * @see java.lang.System#getProperty(java.lang.String)
294 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
295 */
296 public static boolean getBoolean(String name) {
297 boolean result = false;
298 try {
299 result = parseBoolean(System.getProperty(name));
300 } catch (IllegalArgumentException | NullPointerException e) {
301 }
302 return result;
303 }
304
305 /**
306 * Compares this {@code Boolean} instance with another.
307 *
308 * @param b the {@code Boolean} instance to be compared
309 * @return zero if this object represents the same boolean value as the
310 * argument; a positive value if this object represents true
311 * and the argument represents false; and a negative value if
312 * this object represents false and the argument represents true
313 * @throws NullPointerException if the argument is {@code null}
314 * @see Comparable
315 * @since 1.5
316 */
317 public int compareTo(Boolean b) {
318 return compare(this.value, b.value);
319 }
320
321 /**
322 * Compares two {@code boolean} values.
323 * The value returned is identical to what would be returned by:
324 * <pre>
325 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
326 * </pre>
327 *
328 * @param x the first {@code boolean} to compare
329 * @param y the second {@code boolean} to compare
330 * @return the value {@code 0} if {@code x == y};
331 * a value less than {@code 0} if {@code !x && y}; and
332 * a value greater than {@code 0} if {@code x && !y}
333 * @since 1.7
334 */
335 public static int compare(boolean x, boolean y) {
336 return (x == y) ? 0 : (x ? 1 : -1);
337 }
338
339 /**
340 * Returns the result of applying the logical AND 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 AND of {@code a} and {@code b}
346 * @see java.util.function.BinaryOperator
347 * @since 1.8
348 */
349 public static boolean logicalAnd(boolean a, boolean b) {
350 return a && b;
351 }
352
353 /**
354 * Returns the result of applying the logical OR operator to the
355 * specified {@code boolean} operands.
356 *
357 * @param a the first operand
358 * @param b the second operand
359 * @return the logical OR of {@code a} and {@code b}
360 * @see java.util.function.BinaryOperator
361 * @since 1.8
362 */
363 public static boolean logicalOr(boolean a, boolean b) {
364 return a || b;
365 }
366
367 /**
368 * Returns the result of applying the logical XOR operator to the
369 * specified {@code boolean} operands.
370 *
371 * @param a the first operand
372 * @param b the second operand
373 * @return the logical XOR of {@code a} and {@code b}
374 * @see java.util.function.BinaryOperator
375 * @since 1.8
376 */
377 public static boolean logicalXor(boolean a, boolean b) {
378 return a ^ b;
379 }
380
381 /**
382 * Returns an {@link Optional} containing the nominal descriptor for this
383 * instance.
384 *
385 * @return an {@link Optional} describing the {@linkplain Boolean} instance
386 * @since 15
387 */
388 @Override
389 public Optional<DynamicConstantDesc<Boolean>> describeConstable() {
390 return Optional.of(value ? ConstantDescs.TRUE : ConstantDescs.FALSE);
391 }
392 }