1 /*
2 * Copyright (c) 1994, 2013, 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 private static final long serialVersionUID = -3665804199014368530L;
77
78 /**
79 * Allocates a {@code Boolean} object representing the
80 * {@code value} argument.
81 *
82 * @param value the value of the {@code Boolean}.
83 *
84 * @deprecated
85 * It is rarely appropriate to use this constructor. The static factory
86 * {@link #valueOf(boolean)} is generally a better choice, as it is
87 * likely to yield significantly better space and time performance.
88 * Also consider using the final fields {@link #TRUE} and {@link #FALSE}
89 * if possible.
90 */
91 @Deprecated(since="9")
92 public Boolean(boolean value) {
93 this.value = value;
94 }
95
96 /**
97 * Allocates a {@code Boolean} object representing the value
98 * {@code true} if the string argument is not {@code null}
99 * and is equal, ignoring case, to the string {@code "true"}.
100 * Otherwise, allocates a {@code Boolean} object representing the
101 * value {@code false}.
102 *
103 * @param s the string to be converted to a {@code Boolean}.
104 *
105 * @deprecated
106 * It is rarely appropriate to use this constructor.
107 * Use {@link #parseBoolean(String)} to convert a string to a
108 * {@code boolean} primitive, or use {@link #valueOf(String)}
109 * to convert a string to a {@code Boolean} object.
110 */
111 @Deprecated(since="9")
112 public Boolean(String s) {
113 this(parseBoolean(s));
114 }
115
116 /**
117 * Parses the string argument as a boolean. The {@code boolean}
118 * returned represents the value {@code true} if the string argument
119 * is not {@code null} and is equal, ignoring case, to the string
120 * {@code "true"}.
121 * Otherwise, a false value is returned, including for a null
122 * argument.<p>
123 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
124 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
125 *
126 * @param s the {@code String} containing the boolean
127 * representation to be parsed
128 * @return the boolean represented by the string argument
129 * @since 1.5
130 */
131 public static boolean parseBoolean(String s) {
132 return "true".equalsIgnoreCase(s);
133 }
134
135 /**
136 * Returns the value of this {@code Boolean} object as a boolean
137 * primitive.
138 *
139 * @return the primitive {@code boolean} value of this object.
140 */
141 @HotSpotIntrinsicCandidate
142 public boolean booleanValue() {
143 return value;
144 }
145
146 /**
147 * Returns a {@code Boolean} instance representing the specified
148 * {@code boolean} value. If the specified {@code boolean} value
149 * is {@code true}, this method returns {@code Boolean.TRUE};
150 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
151 * If a new {@code Boolean} instance is not required, this method
152 * should generally be used in preference to the constructor
153 * {@link #Boolean(boolean)}, as this method is likely to yield
154 * significantly better space and time performance.
155 *
156 * @param b a boolean value.
157 * @return a {@code Boolean} instance representing {@code b}.
158 * @since 1.4
159 */
160 @HotSpotIntrinsicCandidate
161 public static Boolean valueOf(boolean b) {
162 return (b ? TRUE : FALSE);
163 }
164
165 /**
166 * Returns a {@code Boolean} with a value represented by the
167 * specified string. The {@code Boolean} returned represents a
168 * true value if the string argument is not {@code null}
169 * and is equal, ignoring case, to the string {@code "true"}.
170 * Otherwise, a false value is returned, including for a null
171 * argument.
172 *
173 * @param s a string.
174 * @return the {@code Boolean} value represented by the string.
175 */
176 public static Boolean valueOf(String s) {
177 return parseBoolean(s) ? TRUE : FALSE;
178 }
179
180 /**
181 * Returns a {@code String} object representing the specified
182 * boolean. If the specified boolean is {@code true}, then
183 * the string {@code "true"} will be returned, otherwise the
184 * string {@code "false"} will be returned.
185 *
186 * @param b the boolean to be converted
187 * @return the string representation of the specified {@code boolean}
188 * @since 1.4
189 */
190 public static String toString(boolean b) {
191 return b ? "true" : "false";
192 }
193
194 /**
195 * Returns a {@code String} object representing this Boolean's
196 * value. If this object represents the value {@code true},
197 * a string equal to {@code "true"} is returned. Otherwise, a
198 * string equal to {@code "false"} is returned.
199 *
200 * @return a string representation of this object.
201 */
202 public String toString() {
203 return value ? "true" : "false";
204 }
205
206 /**
207 * Returns a hash code for this {@code Boolean} object.
208 *
209 * @return the integer {@code 1231} if this object represents
210 * {@code true}; returns the integer {@code 1237} if this
211 * object represents {@code false}.
212 */
213 @Override
214 public int hashCode() {
215 return Boolean.hashCode(value);
216 }
217
218 /**
219 * Returns a hash code for a {@code boolean} value; compatible with
220 * {@code Boolean.hashCode()}.
221 *
222 * @param value the value to hash
223 * @return a hash code value for a {@code boolean} value.
224 * @since 1.8
225 */
226 public static int hashCode(boolean value) {
227 return value ? 1231 : 1237;
228 }
229
230 /**
231 * Returns {@code true} if and only if the argument is not
232 * {@code null} and is a {@code Boolean} object that
233 * represents the same {@code boolean} value as this object.
234 *
235 * @param obj the object to compare with.
236 * @return {@code true} if the Boolean objects represent the
237 * same value; {@code false} otherwise.
238 */
239 public boolean equals(Object obj) {
240 if (obj instanceof Boolean) {
241 return value == ((Boolean)obj).booleanValue();
242 }
243 return false;
244 }
245
246 /**
247 * Returns {@code true} if and only if the system property named
248 * by the argument exists and is equal to, ignoring case, the
249 * string {@code "true"}.
250 * A system property is accessible through {@code getProperty}, a
251 * method defined by the {@code System} class. <p> If there is no
252 * property with the specified name, or if the specified name is
253 * empty or null, then {@code false} is returned.
254 *
255 * @param name the system property name.
256 * @return the {@code boolean} value of the system property.
257 * @throws SecurityException for the same reasons as
258 * {@link System#getProperty(String) System.getProperty}
259 * @see java.lang.System#getProperty(java.lang.String)
260 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
261 */
262 public static boolean getBoolean(String name) {
263 boolean result = false;
264 try {
265 result = parseBoolean(System.getProperty(name));
266 } catch (IllegalArgumentException | NullPointerException e) {
267 }
268 return result;
269 }
270
271 /**
272 * Compares this {@code Boolean} instance with another.
273 *
274 * @param b the {@code Boolean} instance to be compared
275 * @return zero if this object represents the same boolean value as the
276 * argument; a positive value if this object represents true
277 * and the argument represents false; and a negative value if
278 * this object represents false and the argument represents true
279 * @throws NullPointerException if the argument is {@code null}
280 * @see Comparable
281 * @since 1.5
282 */
283 public int compareTo(Boolean b) {
284 return compare(this.value, b.value);
285 }
286
287 /**
288 * Compares two {@code boolean} values.
289 * The value returned is identical to what would be returned by:
290 * <pre>
291 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
292 * </pre>
293 *
294 * @param x the first {@code boolean} to compare
295 * @param y the second {@code boolean} to compare
296 * @return the value {@code 0} if {@code x == y};
297 * a value less than {@code 0} if {@code !x && y}; and
298 * a value greater than {@code 0} if {@code x && !y}
299 * @since 1.7
300 */
301 public static int compare(boolean x, boolean y) {
302 return (x == y) ? 0 : (x ? 1 : -1);
303 }
304
305 /**
306 * Returns the result of applying the logical AND operator to the
307 * specified {@code boolean} operands.
308 *
309 * @param a the first operand
310 * @param b the second operand
311 * @return the logical AND of {@code a} and {@code b}
312 * @see java.util.function.BinaryOperator
313 * @since 1.8
314 */
315 public static boolean logicalAnd(boolean a, boolean b) {
316 return a && b;
317 }
318
319 /**
320 * Returns the result of applying the logical OR operator to the
321 * specified {@code boolean} operands.
322 *
323 * @param a the first operand
324 * @param b the second operand
325 * @return the logical OR of {@code a} and {@code b}
326 * @see java.util.function.BinaryOperator
327 * @since 1.8
328 */
329 public static boolean logicalOr(boolean a, boolean b) {
330 return a || b;
331 }
332
333 /**
334 * Returns the result of applying the logical XOR operator to the
335 * specified {@code boolean} operands.
336 *
337 * @param a the first operand
338 * @param b the second operand
339 * @return the logical XOR of {@code a} and {@code b}
340 * @see java.util.function.BinaryOperator
341 * @since 1.8
342 */
343 public static boolean logicalXor(boolean a, boolean b) {
344 return a ^ b;
345 }
346 }
347