1 /*
2 * Copyright (c) 1994, 2019, 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.HotSpotIntrinsicCandidate;
29
30 /**
31 * The Boolean class wraps a value of the primitive type
32 * {@code boolean} in an object. An object of type
33 * {@code Boolean} contains a single field whose type is
34 * {@code boolean}.
35 * <p>
36 * In addition, this class provides many methods for
37 * converting a {@code boolean} to a {@code String} and a
38 * {@code String} to a {@code boolean}, as well as other
39 * constants and methods useful when dealing with a
40 * {@code boolean}.
41 *
42 * @author Arthur van Hoff
43 * @since 1.0
44 */
45 public final class Boolean implements java.io.Serializable,
46 Comparable<Boolean>
47 {
48 /**
49 * The {@code Boolean} object corresponding to the primitive
50 * value {@code true}.
51 */
52 public static final Boolean TRUE = new Boolean(true);
53
54 /**
55 * The {@code Boolean} object corresponding to the primitive
56 * value {@code false}.
57 */
58 public static final Boolean FALSE = new Boolean(false);
59
60 /**
61 * The Class object representing the primitive type boolean.
62 *
63 * @since 1.1
64 */
65 @SuppressWarnings("unchecked")
66 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");
67
68 /**
69 * The value of the Boolean.
70 *
71 * @serial
72 */
73 private final boolean value;
74
75 /** use serialVersionUID from JDK 1.0.2 for interoperability */
76 @java.io.Serial
77 private static final long serialVersionUID = -3665804199014368530L;
78
79 /**
80 * Allocates a {@code Boolean} object representing the
81 * {@code value} argument.
82 *
83 * @param value the value of the {@code Boolean}.
84 *
85 * @deprecated
86 * It is rarely appropriate to use this constructor. The static factory
87 * {@link #valueOf(boolean)} is generally a better choice, as it is
88 * likely to yield significantly better space and time performance.
89 * Also consider using the final fields {@link #TRUE} and {@link #FALSE}
90 * if possible.
91 */
92 @Deprecated(since="9")
93 public Boolean(boolean value) {
94 this.value = value;
95 }
96
97 /**
98 * Allocates a {@code Boolean} object representing the value
99 * {@code true} if the string argument is not {@code null}
100 * and is equal, ignoring case, to the string {@code "true"}.
101 * Otherwise, allocates a {@code Boolean} object representing the
102 * value {@code false}.
103 *
104 * @param s the string to be converted to a {@code Boolean}.
105 *
106 * @deprecated
107 * It is rarely appropriate to use this constructor.
108 * Use {@link #parseBoolean(String)} to convert a string to a
109 * {@code boolean} primitive, or use {@link #valueOf(String)}
110 * to convert a string to a {@code Boolean} object.
111 */
112 @Deprecated(since="9")
113 public Boolean(String s) {
114 this(parseBoolean(s));
115 }
116
117 /**
118 * Parses the string argument as a boolean. The {@code boolean}
119 * returned represents the value {@code true} if the string argument
120 * is not {@code null} and is equal, ignoring case, to the string
121 * {@code "true"}.
122 * Otherwise, a false value is returned, including for a null
123 * argument.<p>
124 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
125 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
126 *
127 * @param s the {@code String} containing the boolean
128 * representation to be parsed
129 * @return the boolean represented by the string argument
130 * @since 1.5
131 */
132 public static boolean parseBoolean(String s) {
133 return "true".equalsIgnoreCase(s);
134 }
135
136 /**
137 * Returns the value of this {@code Boolean} object as a boolean
138 * primitive.
139 *
140 * @return the primitive {@code boolean} value of this object.
141 */
142 @HotSpotIntrinsicCandidate
143 public boolean booleanValue() {
144 return value;
145 }
146
147 /**
148 * Returns a {@code Boolean} instance representing the specified
149 * {@code boolean} value. If the specified {@code boolean} value
150 * is {@code true}, this method returns {@code Boolean.TRUE};
151 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
152 * If a new {@code Boolean} instance is not required, this method
153 * should generally be used in preference to the constructor
154 * {@link #Boolean(boolean)}, as this method is likely to yield
155 * significantly better space and time performance.
156 *
157 * @param b a boolean value.
158 * @return a {@code Boolean} instance representing {@code b}.
159 * @since 1.4
160 */
161 @HotSpotIntrinsicCandidate
162 public static Boolean valueOf(boolean b) {
163 return (b ? TRUE : FALSE);
164 }
165
166 /**
167 * Returns a {@code Boolean} with a value represented by the
168 * specified string. The {@code Boolean} returned represents a
169 * true value if the string argument is not {@code null}
170 * and is equal, ignoring case, to the string {@code "true"}.
171 * Otherwise, a false value is returned, including for a null
172 * argument.
173 *
174 * @param s a string.
175 * @return the {@code Boolean} value represented by the string.
176 */
177 public static Boolean valueOf(String s) {
178 return parseBoolean(s) ? TRUE : FALSE;
179 }
180
181 /**
182 * Returns a {@code String} object representing the specified
183 * boolean. If the specified boolean is {@code true}, then
184 * the string {@code "true"} will be returned, otherwise the
185 * string {@code "false"} will be returned.
186 *
187 * @param b the boolean to be converted
188 * @return the string representation of the specified {@code boolean}
189 * @since 1.4
190 */
191 public static String toString(boolean b) {
192 return b ? "true" : "false";
193 }
194
195 /**
196 * Returns a {@code String} object representing this Boolean's
197 * value. If this object represents the value {@code true},
198 * a string equal to {@code "true"} is returned. Otherwise, a
199 * string equal to {@code "false"} is returned.
200 *
201 * @return a string representation of this object.
202 */
203 public String toString() {
204 return value ? "true" : "false";
205 }
206
207 /**
208 * Returns a hash code for this {@code Boolean} object.
209 *
210 * @return the integer {@code 1231} if this object represents
211 * {@code true}; returns the integer {@code 1237} if this
212 * object represents {@code false}.
213 */
214 @Override
215 public int hashCode() {
216 return Boolean.hashCode(value);
217 }
218
219 /**
220 * Returns a hash code for a {@code boolean} value; compatible with
221 * {@code Boolean.hashCode()}.
222 *
223 * @param value the value to hash
224 * @return a hash code value for a {@code boolean} value.
225 * @since 1.8
226 */
227 public static int hashCode(boolean value) {
228 return value ? 1231 : 1237;
229 }
230
231 /**
232 * Returns {@code true} if and only if the argument is not
233 * {@code null} and is a {@code Boolean} object that
234 * represents the same {@code boolean} value as this object.
235 *
236 * @param obj the object to compare with.
237 * @return {@code true} if the Boolean objects represent the
238 * same value; {@code false} otherwise.
239 */
240 public boolean equals(Object obj) {
241 if (obj instanceof Boolean) {
242 return value == ((Boolean)obj).booleanValue();
243 }
244 return false;
245 }
246
247 /**
248 * Returns {@code true} if and only if the system property named
249 * by the argument exists and is equal to, ignoring case, the
250 * string {@code "true"}.
251 * A system property is accessible through {@code getProperty}, a
252 * method defined by the {@code System} class. <p> If there is no
253 * property with the specified name, or if the specified name is
254 * empty or null, then {@code false} is returned.
255 *
256 * @param name the system property name.
257 * @return the {@code boolean} value of the system property.
258 * @throws SecurityException for the same reasons as
259 * {@link System#getProperty(String) System.getProperty}
260 * @see java.lang.System#getProperty(java.lang.String)
261 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
262 */
263 public static boolean getBoolean(String name) {
264 boolean result = false;
265 try {
266 result = parseBoolean(System.getProperty(name));
267 } catch (IllegalArgumentException | NullPointerException e) {
268 }
269 return result;
270 }
271
272 /**
273 * Compares this {@code Boolean} instance with another.
274 *
275 * @param b the {@code Boolean} instance to be compared
276 * @return zero if this object represents the same boolean value as the
277 * argument; a positive value if this object represents true
278 * and the argument represents false; and a negative value if
279 * this object represents false and the argument represents true
280 * @throws NullPointerException if the argument is {@code null}
281 * @see Comparable
282 * @since 1.5
283 */
284 public int compareTo(Boolean b) {
285 return compare(this.value, b.value);
286 }
287
288 /**
289 * Compares two {@code boolean} values.
290 * The value returned is identical to what would be returned by:
291 * <pre>
292 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
293 * </pre>
294 *
295 * @param x the first {@code boolean} to compare
296 * @param y the second {@code boolean} to compare
297 * @return the value {@code 0} if {@code x == y};
298 * a value less than {@code 0} if {@code !x && y}; and
299 * a value greater than {@code 0} if {@code x && !y}
300 * @since 1.7
301 */
302 public static int compare(boolean x, boolean y) {
303 return (x == y) ? 0 : (x ? 1 : -1);
304 }
305
306 /**
307 * Returns the result of applying the logical AND operator to the
308 * specified {@code boolean} operands.
309 *
310 * @param a the first operand
311 * @param b the second operand
312 * @return the logical AND of {@code a} and {@code b}
313 * @see java.util.function.BinaryOperator
314 * @since 1.8
315 */
316 public static boolean logicalAnd(boolean a, boolean b) {
317 return a && b;
318 }
319
320 /**
321 * Returns the result of applying the logical OR operator to the
322 * specified {@code boolean} operands.
323 *
324 * @param a the first operand
325 * @param b the second operand
326 * @return the logical OR of {@code a} and {@code b}
327 * @see java.util.function.BinaryOperator
328 * @since 1.8
329 */
330 public static boolean logicalOr(boolean a, boolean b) {
331 return a || b;
332 }
333
334 /**
335 * Returns the result of applying the logical XOR operator to the
336 * specified {@code boolean} operands.
337 *
338 * @param a the first operand
339 * @param b the second operand
340 * @return the logical XOR of {@code a} and {@code b}
341 * @see java.util.function.BinaryOperator
342 * @since 1.8
343 */
344 public static boolean logicalXor(boolean a, boolean b) {
345 return a ^ b;
346 }
347 }