1 public final class Boolean implements java.io.Serializable,
2 Comparable<Boolean>
3 {
4 /**
5 * The {@code Boolean} object corresponding to the primitive
6 * value {@code true}.
7 */
8 public static final Boolean TRUE = new Boolean(true);
9
10 /**
11 * The {@code Boolean} object corresponding to the primitive
12 * value {@code false}.
13 */
14 public static final Boolean FALSE = new Boolean(false);
15
16 /**
17 * The Class object representing the primitive type boolean.
18 *
19 * @since JDK1.1
20 */
21 @SuppressWarnings("unchecked")
22 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");
23
24 /**
25 * The value of the Boolean.
26 *
27 * @serial
28 */
29 private final boolean value;
30
31 /** use serialVersionUID from JDK 1.0.2 for interoperability */
32 private static final long serialVersionUID = -3665804199014368530L;
33
34 /**
35 * Allocates a {@code Boolean} object representing the
36 * {@code value} argument.
37 *
38 * <p><b>Note: It is rarely appropriate to use this constructor.
39 * Unless a <i>new</i> instance is required, the static factory
40 * {@link #valueOf(boolean)} is generally a better choice. It is
41 * likely to yield significantly better space and time performance.</b>
42 *
43 * @param value the value of the {@code Boolean}.
44 */
45 public Boolean(boolean value) {
46 this.value = value;
47 }
48
49 /**
50 * Allocates a {@code Boolean} object representing the value
51 * {@code true} if the string argument is not {@code null}
52 * and is equal, ignoring case, to the string {@code "true"}.
53 * Otherwise, allocate a {@code Boolean} object representing the
54 * value {@code false}. Examples:<p>
55 * {@code new Boolean("True")} produces a {@code Boolean} object
56 * that represents {@code true}.<br>
57 * {@code new Boolean("yes")} produces a {@code Boolean} object
58 * that represents {@code false}.
59 *
60 * @param s the string to be converted to a {@code Boolean}.
61 */
62 public Boolean(String s) {
63 this(parseBoolean(s));
64 }
65
66 /**
67 * Parses the string argument as a boolean. The {@code boolean}
68 * returned represents the value {@code true} if the string argument
69 * is not {@code null} and is equal, ignoring case, to the string
70 * {@code "true"}. <p>
71 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
72 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
73 *
74 * @param s the {@code String} containing the boolean
75 * representation to be parsed
76 * @return the boolean represented by the string argument
77 * @since 1.5
78 */
79 public static boolean parseBoolean(String s) {
80 return ((s != null) && s.equalsIgnoreCase("true"));
81 }
82
83 /**
84 * Returns the value of this {@code Boolean} object as a boolean
85 * primitive.
86 *
87 * @return the primitive {@code boolean} value of this object.
88 */
89 public boolean booleanValue() {
90 return value;
91 }
92
93 /**
94 * Returns a {@code Boolean} instance representing the specified
95 * {@code boolean} value. If the specified {@code boolean} value
96 * is {@code true}, this method returns {@code Boolean.TRUE};
97 * if it is {@code false}, this method returns {@code Boolean.FALSE}.
98 * If a new {@code Boolean} instance is not required, this method
99 * should generally be used in preference to the constructor
100 * {@link #Boolean(boolean)}, as this method is likely to yield
101 * significantly better space and time performance.
102 *
103 * @param b a boolean value.
104 * @return a {@code Boolean} instance representing {@code b}.
105 * @since 1.4
106 */
107 public static Boolean valueOf(boolean b) {
108 return (b ? TRUE : FALSE);
109 }
110
111 /**
112 * Returns a {@code Boolean} with a value represented by the
113 * specified string. The {@code Boolean} returned represents a
114 * true value if the string argument is not {@code null}
115 * and is equal, ignoring case, to the string {@code "true"}.
116 *
117 * @param s a string.
118 * @return the {@code Boolean} value represented by the string.
119 */
120 public static Boolean valueOf(String s) {
121 return parseBoolean(s) ? TRUE : FALSE;
122 }
123
124 /**
125 * Returns a {@code String} object representing the specified
126 * boolean. If the specified boolean is {@code true}, then
127 * the string {@code "true"} will be returned, otherwise the
128 * string {@code "false"} will be returned.
129 *
130 * @param b the boolean to be converted
131 * @return the string representation of the specified {@code boolean}
132 * @since 1.4
133 */
134 public static String toString(boolean b) {
135 return b ? "true" : "false";
136 }
137
138 /**
139 * Returns a {@code String} object representing this Boolean‘s
140 * value. If this object represents the value {@code true},
141 * a string equal to {@code "true"} is returned. Otherwise, a
142 * string equal to {@code "false"} is returned.
143 *
144 * @return a string representation of this object.
145 */
146 public String toString() {
147 return value ? "true" : "false";
148 }
149
150 /**
151 * Returns a hash code for this {@code Boolean} object.
152 *
153 * @return the integer {@code 1231} if this object represents
154 * {@code true}; returns the integer {@code 1237} if this
155 * object represents {@code false}.
156 */
157 @Override
158 public int hashCode() {
159 return Boolean.hashCode(value);
160 }
161
162 /**
163 * Returns a hash code for a {@code boolean} value; compatible with
164 * {@code Boolean.hashCode()}.
165 *
166 * @param value the value to hash
167 * @return a hash code value for a {@code boolean} value.
168 * @since 1.8
169 */
170 public static int hashCode(boolean value) {
171 return value ? 1231 : 1237;
172 }
173
174 /**
175 * Returns {@code true} if and only if the argument is not
176 * {@code null} and is a {@code Boolean} object that
177 * represents the same {@code boolean} value as this object.
178 *
179 * @param obj the object to compare with.
180 * @return {@code true} if the Boolean objects represent the
181 * same value; {@code false} otherwise.
182 */
183 public boolean equals(Object obj) {
184 if (obj instanceof Boolean) {
185 return value == ((Boolean)obj).booleanValue();
186 }
187 return false;
188 }
189
190 /**
191 * Returns {@code true} if and only if the system property
192 * named by the argument exists and is equal to the string
193 * {@code "true"}. (Beginning with version 1.0.2 of the
194 * Java<small><sup>TM</sup></small> platform, the test of
195 * this string is case insensitive.) A system property is accessible
196 * through {@code getProperty}, a method defined by the
197 * {@code System} class.
198 * <p>
199 * If there is no property with the specified name, or if the specified
200 * name is empty or null, then {@code false} is returned.
201 *
202 * @param name the system property name.
203 * @return the {@code boolean} value of the system property.
204 * @throws SecurityException for the same reasons as
205 * {@link System#getProperty(String) System.getProperty}
206 * @see java.lang.System#getProperty(java.lang.String)
207 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
208 */
209 public static boolean getBoolean(String name) {
210 boolean result = false;
211 try {
212 result = parseBoolean(System.getProperty(name));
213 } catch (IllegalArgumentException | NullPointerException e) {
214 }
215 return result;
216 }
217
218 /**
219 * Compares this {@code Boolean} instance with another.
220 *
221 * @param b the {@code Boolean} instance to be compared
222 * @return zero if this object represents the same boolean value as the
223 * argument; a positive value if this object represents true
224 * and the argument represents false; and a negative value if
225 * this object represents false and the argument represents true
226 * @throws NullPointerException if the argument is {@code null}
227 * @see Comparable
228 * @since 1.5
229 */
230 public int compareTo(Boolean b) {
231 return compare(this.value, b.value);
232 }
233
234 /**
235 * Compares two {@code boolean} values.
236 * The value returned is identical to what would be returned by:
237 * <pre>
238 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
239 * </pre>
240 *
241 * @param x the first {@code boolean} to compare
242 * @param y the second {@code boolean} to compare
243 * @return the value {@code 0} if {@code x == y};
244 * a value less than {@code 0} if {@code !x && y}; and
245 * a value greater than {@code 0} if {@code x && !y}
246 * @since 1.7
247 */
248 public static int compare(boolean x, boolean y) {
249 return (x == y) ? 0 : (x ? 1 : -1);
250 }
251
252 /**
253 * Returns the result of applying the logical AND operator to the
254 * specified {@code boolean} operands.
255 *
256 * @param a the first operand
257 * @param b the second operand
258 * @return the logical AND of {@code a} and {@code b}
259 * @see java.util.function.BinaryOperator
260 * @since 1.8
261 */
262 public static boolean logicalAnd(boolean a, boolean b) {
263 return a && b;
264 }
265
266 /**
267 * Returns the result of applying the logical OR operator to the
268 * specified {@code boolean} operands.
269 *
270 * @param a the first operand
271 * @param b the second operand
272 * @return the logical OR of {@code a} and {@code b}
273 * @see java.util.function.BinaryOperator
274 * @since 1.8
275 */
276 public static boolean logicalOr(boolean a, boolean b) {
277 return a || b;
278 }
279
280 /**
281 * Returns the result of applying the logical XOR operator to the
282 * specified {@code boolean} operands.
283 *
284 * @param a the first operand
285 * @param b the second operand
286 * @return the logical XOR of {@code a} and {@code b}
287 * @see java.util.function.BinaryOperator
288 * @since 1.8
289 */
290 public static boolean logicalXor(boolean a, boolean b) {
291 return a ^ b;
292 }
293 }
