- 001
/* - 002
* @(#)Boolean.java 1.53 05/11/17 - 003 *
- 004 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
- 005 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- 006
*/ - 007
- 008package java.lang;
- 009
- 010/**
- 011 * The Boolean class wraps a value of the primitive type
- 012 * <code>boolean</code> in an object. An object of type
- 013 * <code>Boolean</code> contains a single field whose type is
- 014 * <code>boolean</code>.
- 015 * <p>
- 016 * In addition, this class provides many methods for
- 017 * converting a <code>boolean</code> to a <code>String</code> and a
- 018 * <code>String</code> to a <code>boolean</code>, as well as other
- 019 * constants and methods useful when dealing with a
- 020 * <code>boolean</code>.
- 021 *
- 022 * @author Arthur van Hoff
- 023 * @version 1.53, 11/17/05
- 024 * @since JDK1.0
- 025 */
- 026public final class Boolean implements java.io.Serializable,
- 027 Comparable<Boolean>
- 028{
- 029 /**
- 030 * The <code>Boolean</code> object corresponding to the primitive
- 031 * value <code>true</code>.
- 032 */
- 033 public static final Boolean TRUE = new Boolean(true);
- 034
- 035 /**
- 036 * The <code>Boolean</code> object corresponding to the primitive
- 037 * value <code>false</code>.
- 038 */
- 039 public static final Boolean FALSE = new Boolean(false);
- 040
- 041 /**
- 042 * The Class object representing the primitive type boolean.
- 043 *
- 044 * @since JDK1.1
- 045 */
- 046 public static final Class<Boolean> TYPE = Class.getPrimitiveClass("boolean");
- 047
- 048 /**
- 049 * The value of the Boolean.
- 050 *
- 051 * @serial
- 052 */
- 053 private final boolean value;
- 054
- 055 /** use serialVersionUID from JDK 1.0.2 for interoperability */
- 056 private static final long serialVersionUID = -3665804199014368530L;
- 057
- 058 /**
- 059 * Allocates a <code>Boolean</code> object representing the
- 060 * <code>value</code> argument.
- 061 *
- 062 * <p><b>Note: It is rarely appropriate to use this constructor.
- 063 * Unless a <i>new</i> instance is required, the static factory
- 064 * {@link #valueOf(boolean)} is generally a better choice. It is
- 065 * likely to yield significantly better space and time performance.</b>
- 066 *
- 067 * @param value the value of the <code>Boolean</code>.
- 068 */
- 069 public Boolean(boolean value) {
- 070 this.value = value;
- 071 }
- 072
- 073 /**
- 074 * Allocates a <code>Boolean</code> object representing the value
- 075 * <code>true</code> if the string argument is not <code>null</code>
- 076 * and is equal, ignoring case, to the string {@code "true"}.
- 077 * Otherwise, allocate a <code>Boolean</code> object representing the
- 078 * value <code>false</code>. Examples:<p>
- 079 * {@code new Boolean("True")} produces a <tt>Boolean</tt> object
- 080 * that represents <tt>true</tt>.<br>
- 081 * {@code new Boolean("yes")} produces a <tt>Boolean</tt> object
- 082 * that represents <tt>false</tt>.
- 083 *
- 084 * @param s the string to be converted to a <code>Boolean</code>.
- 085 */
- 086 public Boolean(String s) {
- 087 this(toBoolean(s));
- 088 }
- 089
- 090 /**
- 091 * Parses the string argument as a boolean. The <code>boolean</code>
- 092 * returned represents the value <code>true</code> if the string argument
- 093 * is not <code>null</code> and is equal, ignoring case, to the string
- 094 * {@code "true"}. <p>
- 095 * Example: {@code Boolean.parseBoolean("True")} returns <tt>true</tt>.<br>
- 096 * Example: {@code Boolean.parseBoolean("yes")} returns <tt>false</tt>.
- 097 *
- 098 * @param s the <code>String</code> containing the boolean
- 099 * representation to be parsed
- 100 * @return the boolean represented by the string argument
- 101 * @since 1.5
- 102 */
- 103 public static boolean parseBoolean(String s) {
- 104 return toBoolean(s);
- 105 }
- 106
- 107 /**
- 108 * Returns the value of this <tt>Boolean</tt> object as a boolean
- 109 * primitive.
- 110 *
- 111 * @return the primitive <code>boolean</code> value of this object.
- 112 */
- 113 public boolean booleanValue() {
- 114 return value;
- 115 }
- 116
- 117 /**
- 118 * Returns a <tt>Boolean</tt> instance representing the specified
- 119 * <tt>boolean</tt> value. If the specified <tt>boolean</tt> value
- 120 * is <tt>true</tt>, this method returns <tt>Boolean.TRUE</tt>;
- 121 * if it is <tt>false</tt>, this method returns <tt>Boolean.FALSE</tt>.
- 122 * If a new <tt>Boolean</tt> instance is not required, this method
- 123 * should generally be used in preference to the constructor
- 124 * {@link #Boolean(boolean)}, as this method is likely to yield
- 125 * significantly better space and time performance.
- 126 *
- 127 * @param b a boolean value.
- 128 * @return a <tt>Boolean</tt> instance representing <tt>b</tt>.
- 129 * @since 1.4
- 130 */
- 131 public static Boolean valueOf(boolean b) {
- 132 return (b ? TRUE : FALSE);
- 133 }
- 134
- 135 /**
- 136 * Returns a <code>Boolean</code> with a value represented by the
- 137 * specified string. The <code>Boolean</code> returned represents a
- 138 * true value if the string argument is not <code>null</code>
- 139 * and is equal, ignoring case, to the string {@code "true"}.
- 140 *
- 141 * @param s a string.
- 142 * @return the <code>Boolean</code> value represented by the string.
- 143 */
- 144 public static Boolean valueOf(String s) {
- 145 return toBoolean(s) ? TRUE : FALSE;
- 146 }
- 147
- 148 /**
- 149 * Returns a <tt>String</tt> object representing the specified
- 150 * boolean. If the specified boolean is <code>true</code>, then
- 151 * the string {@code "true"} will be returned, otherwise the
- 152 * string {@code "false"} will be returned.
- 153 *
- 154 * @param b the boolean to be converted
- 155 * @return the string representation of the specified <code>boolean</code>
- 156 * @since 1.4
- 157 */
- 158 public static String toString(boolean b) {
- 159 return b ? "true" : "false";
- 160 }
- 161
- 162 /**
- 163 * Returns a <tt>String</tt> object representing this Boolean's
- 164 * value. If this object represents the value <code>true</code>,
- 165 * a string equal to {@code "true"} is returned. Otherwise, a
- 166 * string equal to {@code "false"} is returned.
- 167 *
- 168 * @return a string representation of this object.
- 169 */
- 170 public String toString() {
- 171 return value ? "true" : "false";
- 172 }
- 173
- 174 /**
- 175 * Returns a hash code for this <tt>Boolean</tt> object.
- 176 *
- 177 * @return the integer <tt>1231</tt> if this object represents
- 178 * <tt>true</tt>; returns the integer <tt>1237</tt> if this
- 179 * object represents <tt>false</tt>.
- 180 */
- 181 public int hashCode() {
- 182 return value ? 1231 : 1237;
- 183 }
- 184
- 185 /**
- 186 * Returns <code>true</code> if and only if the argument is not
- 187 * <code>null</code> and is a <code>Boolean</code> object that
- 188 * represents the same <code>boolean</code> value as this object.
- 189 *
- 190 * @param obj the object to compare with.
- 191 * @return <code>true</code> if the Boolean objects represent the
- 192 * same value; <code>false</code> otherwise.
- 193 */
- 194 public boolean equals(Object obj) {
- 195 if (obj instanceof Boolean) {
- 196 return value == ((Boolean)obj).booleanValue();
- 197 }
- 198 return false;
- 199 }
- 200
- 201 /**
- 202 * Returns <code>true</code> if and only if the system property
- 203 * named by the argument exists and is equal to the string
- 204 * {@code "true"}. (Beginning with version 1.0.2 of the
- 205 * Java<small><sup>TM</sup></small> platform, the test of
- 206 * this string is case insensitive.) A system property is accessible
- 207 * through <code>getProperty</code>, a method defined by the
- 208 * <code>System</code> class.
- 209 * <p>
- 210 * If there is no property with the specified name, or if the specified
- 211 * name is empty or null, then <code>false</code> is returned.
- 212 *
- 213 * @param name the system property name.
- 214 * @return the <code>boolean</code> value of the system property.
- 215 * @see java.lang.System#getProperty(java.lang.String)
- 216 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
- 217 */
- 218 public static boolean getBoolean(String name) {
- 219 boolean result = false;
- 220 try {
- 221 result = toBoolean(System.getProperty(name));
- 222 } catch (IllegalArgumentException e) {
- 223 } catch (NullPointerException e) {
- 224 }
- 225 return result;
- 226 }
- 227
- 228 /**
- 229 * Compares this <tt>Boolean</tt> instance with another.
- 230 *
- 231 * @param b the <tt>Boolean</tt> instance to be compared
- 232 * @return zero if this object represents the same boolean value as the
- 233 * argument; a positive value if this object represents true
- 234 * and the argument represents false; and a negative value if
- 235 * this object represents false and the argument represents true
- 236 * @throws NullPointerException if the argument is <tt>null</tt>
- 237 * @see Comparable
- 238 * @since 1.5
- 239 */
- 240 public int compareTo(Boolean b) {
- 241 return (b.value == value ? 0 : (value ? 1 : -1));
- 242 }
- 243
- 244 private static boolean toBoolean(String name) {
- 245 return ((name != null) && name.equalsIgnoreCase("true"));
- 246 }
- 247}
