- Boolean源码比较简单。
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 }
原文地址：https://www.cnblogs.com/aben-blog/p/8729428.html
时间： 2024-11-05 21:47:22