001 /* Boolean.java -- object wrapper for boolean
002 Copyright (C) 1998, 2001, 2002, 2004, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.lang;
040
041 import java.io.Serializable;
042
043 /**
044 * Instances of class <code>Boolean</code> represent primitive
045 * <code>boolean</code> values.
046 *
047 * @author Paul Fisher
048 * @author Eric Blake (ebb9@email.byu.edu)
049 * @since 1.0
050 * @status updated to 1.5
051 */
052 public final class Boolean implements Serializable, Comparable<Boolean>
053 {
054 /**
055 * Compatible with JDK 1.0.2+.
056 */
057 private static final long serialVersionUID = -3665804199014368530L;
058
059 /**
060 * This field is a <code>Boolean</code> object representing the
061 * primitive value <code>true</code>. This instance is returned
062 * by the static <code>valueOf()</code> methods if they return
063 * a <code>Boolean</code> representing <code>true</code>.
064 */
065 public static final Boolean TRUE = new Boolean(true);
066
067 /**
068 * This field is a <code>Boolean</code> object representing the
069 * primitive value <code>false</code>. This instance is returned
070 * by the static <code>valueOf()</code> methods if they return
071 * a <code>Boolean</code> representing <code>false</code>.
072 */
073 public static final Boolean FALSE = new Boolean(false);
074
075 /**
076 * The primitive type <code>boolean</code> is represented by this
077 * <code>Class</code> object.
078 *
079 * @since 1.1
080 */
081 public static final Class<Boolean> TYPE = (Class<Boolean>) VMClassLoader.getPrimitiveClass('Z');
082
083 /**
084 * The immutable value of this Boolean.
085 * @serial the wrapped value
086 */
087 private final boolean value;
088
089 /**
090 * Create a <code>Boolean</code> object representing the value of the
091 * argument <code>value</code>. In general the use of the static
092 * method <code>valueof(boolean)</code> is more efficient since it will
093 * not create a new object.
094 *
095 * @param value the primitive value of this <code>Boolean</code>
096 * @see #valueOf(boolean)
097 */
098 public Boolean(boolean value)
099 {
100 this.value = value;
101 }
102
103 /**
104 * Creates a <code>Boolean</code> object representing the primitive
105 * <code>true</code> if and only if <code>s</code> matches
106 * the string "true" ignoring case, otherwise the object will represent
107 * the primitive <code>false</code>. In general the use of the static
108 * method <code>valueof(String)</code> is more efficient since it will
109 * not create a new object.
110 *
111 * @param s the <code>String</code> representation of <code>true</code>
112 * or false
113 */
114 public Boolean(String s)
115 {
116 value = "true".equalsIgnoreCase(s);
117 }
118
119 /**
120 * Return the primitive <code>boolean</code> value of this
121 * <code>Boolean</code> object.
122 *
123 * @return true or false, depending on the value of this Boolean
124 */
125 public boolean booleanValue()
126 {
127 return value;
128 }
129
130 /**
131 * Returns the Boolean <code>TRUE</code> if the given boolean is
132 * <code>true</code>, otherwise it will return the Boolean
133 * <code>FALSE</code>.
134 *
135 * @param b the boolean to wrap
136 * @return the wrapper object
137 * @see #TRUE
138 * @see #FALSE
139 * @since 1.4
140 */
141 public static Boolean valueOf(boolean b)
142 {
143 return b ? TRUE : FALSE;
144 }
145
146 /**
147 * Returns the Boolean <code>TRUE</code> if and only if the given
148 * String is equal, ignoring case, to the the String "true", otherwise
149 * it will return the Boolean <code>FALSE</code>.
150 *
151 * @param s the string to convert
152 * @return a wrapped boolean from the string
153 */
154 public static Boolean valueOf(String s)
155 {
156 return "true".equalsIgnoreCase(s) ? TRUE : FALSE;
157 }
158
159 /**
160 * Returns "true" if the value of the give boolean is <code>true</code> and
161 * returns "false" if the value of the given boolean is <code>false</code>.
162 *
163 * @param b the boolean to convert
164 * @return the string representation of the boolean
165 * @since 1.4
166 */
167 public static String toString(boolean b)
168 {
169 return b ? "true" : "false";
170 }
171
172 /**
173 * Returns "true" if the value of this object is <code>true</code> and
174 * returns "false" if the value of this object is <code>false</code>.
175 *
176 * @return the string representation of this
177 */
178 public String toString()
179 {
180 return value ? "true" : "false";
181 }
182
183 /**
184 * Returns the integer <code>1231</code> if this object represents
185 * the primitive <code>true</code> and the integer <code>1237</code>
186 * otherwise.
187 *
188 * @return the hash code
189 */
190 public int hashCode()
191 {
192 return value ? 1231 : 1237;
193 }
194
195 /**
196 * If the <code>obj</code> is an instance of <code>Boolean</code> and
197 * has the same primitive value as this object then <code>true</code>
198 * is returned. In all other cases, including if the <code>obj</code>
199 * is <code>null</code>, <code>false</code> is returned.
200 *
201 * @param obj possibly an instance of any <code>Class</code>
202 * @return true if <code>obj</code> equals this
203 */
204 public boolean equals(Object obj)
205 {
206 return obj instanceof Boolean && value == ((Boolean) obj).value;
207 }
208
209 /**
210 * If the value of the system property <code>name</code> matches
211 * "true" ignoring case then the function returns <code>true</code>.
212 *
213 * @param name the property name to look up
214 * @return true if the property resulted in "true"
215 * @throws SecurityException if accessing the system property is forbidden
216 * @see System#getProperty(String)
217 */
218 public static boolean getBoolean(String name)
219 {
220 if (name == null || "".equals(name))
221 return false;
222 return "true".equalsIgnoreCase(System.getProperty(name));
223 }
224
225 /**
226 * Compares this Boolean to another.
227 *
228 * @param other the Boolean to compare this Boolean to
229 * @return 0 if both Booleans represent the same value, a positive number
230 * if this Boolean represents true and the other false, and a negative
231 * number otherwise.
232 * @since 1.5
233 */
234 public int compareTo(Boolean other)
235 {
236 return value == other.value ? 0 : (value ? 1 : -1);
237 }
238
239 /**
240 * If the String argument is "true", ignoring case, return true.
241 * Otherwise, return false.
242 *
243 * @param b String to parse
244 * @since 1.5
245 */
246 public static boolean parseBoolean(String b)
247 {
248 return "true".equalsIgnoreCase(b) ? true : false;
249 }
250
251 }