1 /*
2 * Copyright (c) 1994, 2021, 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 Boolean class wraps a value of the primitive type
41 * {@code boolean} in an object. An object of type
42 * {@code Boolean} contains a single field whose type is
43 * {@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.MigratedValueClass
61 @jdk.internal.ValueBased
62 public final class Boolean implements java.io.Serializable,
63 Comparable<Boolean>, Constable
64 {
65 /**
66 * The {@code Boolean} object corresponding to the primitive
67 * value {@code true}.
68 */
69 public static final Boolean TRUE = new Boolean(true);
70
71 /**
72 * The {@code Boolean} object corresponding to the primitive
73 * value {@code false}.
74 */
75 public static final Boolean FALSE = new Boolean(false);
76
77 /**
78 * The Class object representing the primitive type boolean.
79 *
80 * @since 1.1
81 */
82 @SuppressWarnings("unchecked")
83 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");
84
85 /**
86 * The value of the Boolean.
87 *
88 * @serial
89 */
90 private final boolean value;
91
92 /** use serialVersionUID from JDK 1.0.2 for interoperability */
93 @java.io.Serial
94 private static final long serialVersionUID = -3665804199014368530L;
95
96 /**
97 * Allocates a {@code Boolean} object representing the
98 * {@code value} argument.
99 *
100 * @param value the value of the {@code Boolean}.
101 *
102 * @deprecated
103 * It is rarely appropriate to use this constructor. The static factory
104 * {@link #valueOf(boolean)} is generally a better choice, as it is
105 * likely to yield significantly better space and time performance.
106 * Also consider using the final fields {@link #TRUE} and {@link #FALSE}
107 * if possible.
108 */
109 @Deprecated(since="9", forRemoval = true)
110 public Boolean(boolean value) {
111 this.value = value;
112 }
113
114 /**
115 * Allocates a {@code Boolean} object representing the value
116 * {@code true} if the string argument is not {@code null}
117 * and is equal, ignoring case, to the string {@code "true"}.
118 * Otherwise, allocates a {@code Boolean} object representing the
119 * value {@code false}.
120 *
121 * @param s the string to be converted to a {@code Boolean}.
122 *
123 * @deprecated
124 * It is rarely appropriate to use this constructor.
125 * Use {@link #parseBoolean(String)} to convert a string to a
126 * {@code boolean} primitive, or use {@link #valueOf(String)}
127 * to convert a string to a {@code Boolean} object.
128 */
129 @Deprecated(since="9", forRemoval = true)
130 public Boolean(String s) {
131 this(parseBoolean(s));
132 }
133
134 /**
135 * Parses the string argument as a boolean. The {@code boolean}
136 * returned represents the value {@code true} if the string argument
137 * is not {@code null} and is equal, ignoring case, to the string
138 * {@code "true"}.
139 * Otherwise, a false value is returned, including for a null
140 * argument.<p>
141 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
142 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
143 *
144 * @param s the {@code String} containing the boolean
145 * representation to be parsed
146 * @return the boolean represented by the string argument
147 * @since 1.5
148 */
149 public static boolean parseBoolean(String s) {
150 return "true".equalsIgnoreCase(s);
151 }
152
153 /**
154 * Returns the value of this {@code Boolean} object as a boolean
155 * primitive.
156 *
157 * @return the primitive {@code boolean} value of this object.
158 */
159 @IntrinsicCandidate
160 public boolean booleanValue() {
161 return value;
162 }
163
164 /**
165 * Returns a {@code Boolean} instance representing the specified
166 * {@code boolean} value. If the specified {@code boolean} value
167 * is {@code true}, this method returns {@code Boolean.TRUE};
168 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
169 * If a new {@code Boolean} instance is not required, this method
170 * should generally be used in preference to the constructor
171 * {@link #Boolean(boolean)}, as this method is likely to yield
172 * significantly better space and time performance.
173 *
174 * @param b a boolean value.
175 * @return a {@code Boolean} instance representing {@code b}.
176 * @since 1.4
177 */
178 @IntrinsicCandidate
179 public static Boolean valueOf(boolean b) {
180 return (b ? TRUE : FALSE);
181 }
182
183 /**
184 * Returns a {@code Boolean} with a value represented by the
185 * specified string. The {@code Boolean} returned represents a
186 * true value if the string argument is not {@code null}
187 * and is equal, ignoring case, to the string {@code "true"}.
188 * Otherwise, a false value is returned, including for a null
189 * argument.
190 *
191 * @param s a string.
192 * @return the {@code Boolean} value represented by the string.
193 */
194 public static Boolean valueOf(String s) {
195 return parseBoolean(s) ? TRUE : FALSE;
196 }
197
198 /**
199 * Returns a {@code String} object representing the specified
200 * boolean. If the specified boolean is {@code true}, then
201 * the string {@code "true"} will be returned, otherwise the
202 * string {@code "false"} will be returned.
203 *
204 * @param b the boolean to be converted
205 * @return the string representation of the specified {@code boolean}
206 * @since 1.4
207 */
208 public static String toString(boolean b) {
209 return String.valueOf(b);
210 }
211
212 /**
213 * Returns a {@code String} object representing this Boolean's
214 * value. If this object represents the value {@code true},
215 * a string equal to {@code "true"} is returned. Otherwise, a
216 * string equal to {@code "false"} is returned.
217 *
218 * @return a string representation of this object.
219 */
220 @Override
221 public String toString() {
222 return String.valueOf(value);
223 }
224
225 /**
226 * Returns a hash code for this {@code Boolean} object.
227 *
228 * @return the integer {@code 1231} if this object represents
229 * {@code true}; returns the integer {@code 1237} if this
230 * object represents {@code false}.
231 */
232 @Override
233 public int hashCode() {
234 return Boolean.hashCode(value);
235 }
236
237 /**
238 * Returns a hash code for a {@code boolean} value; compatible with
239 * {@code Boolean.hashCode()}.
240 *
241 * @param value the value to hash
242 * @return a hash code value for a {@code boolean} value.
243 * @since 1.8
244 */
245 public static int hashCode(boolean value) {
246 return value ? 1231 : 1237;
247 }
248
249 /**
250 * Returns {@code true} if and only if the argument is not
251 * {@code null} and is a {@code Boolean} object that
252 * represents the same {@code boolean} value as this object.
253 *
254 * @param obj the object to compare with.
255 * @return {@code true} if the Boolean objects represent the
256 * same value; {@code false} otherwise.
257 */
258 public boolean equals(Object obj) {
259 if (obj instanceof Boolean) {
260 return value == ((Boolean)obj).booleanValue();
261 }
262 return false;
263 }
264
265 /**
266 * Returns {@code true} if and only if the system property named
267 * by the argument exists and is equal to, ignoring case, the
268 * string {@code "true"}.
269 * A system property is accessible through {@code getProperty}, a
270 * method defined by the {@code System} class. <p> If there is no
271 * property with the specified name, or if the specified name is
272 * empty or null, then {@code false} is returned.
273 *
274 * @param name the system property name.
275 * @return the {@code boolean} value of the system property.
276 * @throws SecurityException for the same reasons as
277 * {@link System#getProperty(String) System.getProperty}
278 * @see java.lang.System#getProperty(java.lang.String)
279 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
280 */
281 public static boolean getBoolean(String name) {
282 boolean result = false;
283 try {
284 result = parseBoolean(System.getProperty(name));
285 } catch (IllegalArgumentException | NullPointerException e) {
286 }
287 return result;
288 }
289
290 /**
291 * Compares this {@code Boolean} instance with another.
292 *
293 * @param b the {@code Boolean} instance to be compared
294 * @return zero if this object represents the same boolean value as the
295 * argument; a positive value if this object represents true
296 * and the argument represents false; and a negative value if
297 * this object represents false and the argument represents true
298 * @throws NullPointerException if the argument is {@code null}
299 * @see Comparable
300 * @since 1.5
301 */
302 public int compareTo(Boolean b) {
303 return compare(this.value, b.value);
304 }
305
306 /**
307 * Compares two {@code boolean} values.
308 * The value returned is identical to what would be returned by:
309 * <pre>
310 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
311 * </pre>
312 *
313 * @param x the first {@code boolean} to compare
314 * @param y the second {@code boolean} to compare
315 * @return the value {@code 0} if {@code x == y};
316 * a value less than {@code 0} if {@code !x && y}; and
317 * a value greater than {@code 0} if {@code x && !y}
318 * @since 1.7
319 */
320 public static int compare(boolean x, boolean y) {
321 return (x == y) ? 0 : (x ? 1 : -1);
322 }
323
324 /**
325 * Returns the result of applying the logical AND operator to the
326 * specified {@code boolean} operands.
327 *
328 * @param a the first operand
329 * @param b the second operand
330 * @return the logical AND of {@code a} and {@code b}
331 * @see java.util.function.BinaryOperator
332 * @since 1.8
333 */
334 public static boolean logicalAnd(boolean a, boolean b) {
335 return a && b;
336 }
337
338 /**
339 * Returns the result of applying the logical OR operator to the
340 * specified {@code boolean} operands.
341 *
342 * @param a the first operand
343 * @param b the second operand
344 * @return the logical OR of {@code a} and {@code b}
345 * @see java.util.function.BinaryOperator
346 * @since 1.8
347 */
348 public static boolean logicalOr(boolean a, boolean b) {
349 return a || b;
350 }
351
352 /**
353 * Returns the result of applying the logical XOR operator to the
354 * specified {@code boolean} operands.
355 *
356 * @param a the first operand
357 * @param b the second operand
358 * @return the logical XOR of {@code a} and {@code b}
359 * @see java.util.function.BinaryOperator
360 * @since 1.8
361 */
362 public static boolean logicalXor(boolean a, boolean b) {
363 return a ^ b;
364 }
365
366 /**
367 * Returns an {@link Optional} containing the nominal descriptor for this
368 * instance.
369 *
370 * @return an {@link Optional} describing the {@linkplain Boolean} instance
371 * @since 15
372 */
373 @Override
374 public Optional<DynamicConstantDesc<Boolean>> describeConstable() {
375 return Optional.of(value ? ConstantDescs.TRUE : ConstantDescs.FALSE);
376 }
377 }