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336 lines
11 KiB
336 lines
11 KiB
/*
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* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.lang;
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/**
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* The Boolean class wraps a value of the primitive type
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* {@code boolean} in an object. An object of type
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* {@code Boolean} contains a single field whose type is
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* {@code boolean}.
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* <p>
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* In addition, this class provides many methods for
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* converting a {@code boolean} to a {@code String} and a
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* {@code String} to a {@code boolean}, as well as other
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* constants and methods useful when dealing with a
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* {@code boolean}.
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*
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* @author Arthur van Hoff
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* @since JDK1.0
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*/
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public final class Boolean implements java.io.Serializable,
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Comparable<Boolean>
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{
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/**
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* The {@code Boolean} object corresponding to the primitive
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* value {@code true}.
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*/
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public static final Boolean TRUE = new Boolean(true);
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/**
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* The {@code Boolean} object corresponding to the primitive
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* value {@code false}.
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*/
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public static final Boolean FALSE = new Boolean(false);
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/**
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* The Class object representing the primitive type boolean.
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*
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* @since JDK1.1
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*/
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@SuppressWarnings("unchecked")
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public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");
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/**
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* The value of the Boolean.
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*
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* @serial
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*/
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private final boolean value;
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/** use serialVersionUID from JDK 1.0.2 for interoperability */
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private static final long serialVersionUID = -3665804199014368530L;
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/**
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* Allocates a {@code Boolean} object representing the
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* {@code value} argument.
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*
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* <p><b>Note: It is rarely appropriate to use this constructor.
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* Unless a <i>new</i> instance is required, the static factory
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* {@link #valueOf(boolean)} is generally a better choice. It is
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* likely to yield significantly better space and time performance.</b>
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*
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* @param value the value of the {@code Boolean}.
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*/
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public Boolean(boolean value) {
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this.value = value;
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}
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/**
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* Allocates a {@code Boolean} object representing the value
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* {@code true} if the string argument is not {@code null}
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* and is equal, ignoring case, to the string {@code "true"}.
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* Otherwise, allocate a {@code Boolean} object representing the
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* value {@code false}. Examples:<p>
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* {@code new Boolean("True")} produces a {@code Boolean} object
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* that represents {@code true}.<br>
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* {@code new Boolean("yes")} produces a {@code Boolean} object
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* that represents {@code false}.
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*
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* @param s the string to be converted to a {@code Boolean}.
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*/
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public Boolean(String s) {
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this(parseBoolean(s));
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}
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/**
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* Parses the string argument as a boolean. The {@code boolean}
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* returned represents the value {@code true} if the string argument
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* is not {@code null} and is equal, ignoring case, to the string
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* {@code "true"}. <p>
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* Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
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* Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
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*
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* @param s the {@code String} containing the boolean
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* representation to be parsed
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* @return the boolean represented by the string argument
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* @since 1.5
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*/
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public static boolean parseBoolean(String s) {
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return ((s != null) && s.equalsIgnoreCase("true"));
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}
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/**
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* Returns the value of this {@code Boolean} object as a boolean
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* primitive.
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*
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* @return the primitive {@code boolean} value of this object.
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*/
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public boolean booleanValue() {
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return value;
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}
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/**
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* Returns a {@code Boolean} instance representing the specified
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* {@code boolean} value. If the specified {@code boolean} value
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* is {@code true}, this method returns {@code Boolean.TRUE};
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* if it is {@code false}, this method returns {@code Boolean.FALSE}.
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* If a new {@code Boolean} instance is not required, this method
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* should generally be used in preference to the constructor
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* {@link #Boolean(boolean)}, as this method is likely to yield
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* significantly better space and time performance.
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*
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* @param b a boolean value.
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* @return a {@code Boolean} instance representing {@code b}.
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* @since 1.4
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*/
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public static Boolean valueOf(boolean b) {
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return (b ? TRUE : FALSE);
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}
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/**
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* Returns a {@code Boolean} with a value represented by the
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* specified string. The {@code Boolean} returned represents a
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* true value if the string argument is not {@code null}
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* and is equal, ignoring case, to the string {@code "true"}.
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*
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* @param s a string.
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* @return the {@code Boolean} value represented by the string.
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*/
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public static Boolean valueOf(String s) {
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return parseBoolean(s) ? TRUE : FALSE;
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}
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/**
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* Returns a {@code String} object representing the specified
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* boolean. If the specified boolean is {@code true}, then
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* the string {@code "true"} will be returned, otherwise the
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* string {@code "false"} will be returned.
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*
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* @param b the boolean to be converted
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* @return the string representation of the specified {@code boolean}
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* @since 1.4
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*/
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public static String toString(boolean b) {
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return b ? "true" : "false";
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}
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/**
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* Returns a {@code String} object representing this Boolean's
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* value. If this object represents the value {@code true},
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* a string equal to {@code "true"} is returned. Otherwise, a
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* string equal to {@code "false"} is returned.
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*
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* @return a string representation of this object.
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*/
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public String toString() {
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return value ? "true" : "false";
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}
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/**
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* Returns a hash code for this {@code Boolean} object.
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*
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* @return the integer {@code 1231} if this object represents
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* {@code true}; returns the integer {@code 1237} if this
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* object represents {@code false}.
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*/
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@Override
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public int hashCode() {
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return Boolean.hashCode(value);
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}
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/**
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* Returns a hash code for a {@code boolean} value; compatible with
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* {@code Boolean.hashCode()}.
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*
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* @param value the value to hash
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* @return a hash code value for a {@code boolean} value.
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* @since 1.8
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*/
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public static int hashCode(boolean value) {
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return value ? 1231 : 1237;
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}
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/**
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* Returns {@code true} if and only if the argument is not
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* {@code null} and is a {@code Boolean} object that
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* represents the same {@code boolean} value as this object.
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*
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* @param obj the object to compare with.
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* @return {@code true} if the Boolean objects represent the
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* same value; {@code false} otherwise.
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*/
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public boolean equals(Object obj) {
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if (obj instanceof Boolean) {
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return value == ((Boolean)obj).booleanValue();
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}
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return false;
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}
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/**
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* Returns {@code true} if and only if the system property
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* named by the argument exists and is equal to the string
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* {@code "true"}. (Beginning with version 1.0.2 of the
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* Java<small><sup>TM</sup></small> platform, the test of
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* this string is case insensitive.) A system property is accessible
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* through {@code getProperty}, a method defined by the
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* {@code System} class.
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* <p>
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* If there is no property with the specified name, or if the specified
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* name is empty or null, then {@code false} is returned.
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*
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* @param name the system property name.
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* @return the {@code boolean} value of the system property.
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* @throws SecurityException for the same reasons as
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* {@link System#getProperty(String) System.getProperty}
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* @see java.lang.System#getProperty(java.lang.String)
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* @see java.lang.System#getProperty(java.lang.String, java.lang.String)
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*/
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public static boolean getBoolean(String name) {
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boolean result = false;
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try {
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result = parseBoolean(System.getProperty(name));
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} catch (IllegalArgumentException | NullPointerException e) {
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}
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return result;
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}
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/**
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* Compares this {@code Boolean} instance with another.
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*
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* @param b the {@code Boolean} instance to be compared
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* @return zero if this object represents the same boolean value as the
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* argument; a positive value if this object represents true
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* and the argument represents false; and a negative value if
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* this object represents false and the argument represents true
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* @throws NullPointerException if the argument is {@code null}
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* @see Comparable
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* @since 1.5
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*/
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public int compareTo(Boolean b) {
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return compare(this.value, b.value);
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}
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/**
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* Compares two {@code boolean} values.
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* The value returned is identical to what would be returned by:
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* <pre>
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* Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
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* </pre>
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*
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* @param x the first {@code boolean} to compare
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* @param y the second {@code boolean} to compare
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* @return the value {@code 0} if {@code x == y};
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* a value less than {@code 0} if {@code !x && y}; and
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* a value greater than {@code 0} if {@code x && !y}
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* @since 1.7
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*/
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public static int compare(boolean x, boolean y) {
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return (x == y) ? 0 : (x ? 1 : -1);
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}
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/**
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* Returns the result of applying the logical AND operator to the
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* specified {@code boolean} operands.
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*
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* @param a the first operand
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* @param b the second operand
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* @return the logical AND of {@code a} and {@code b}
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* @see java.util.function.BinaryOperator
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* @since 1.8
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*/
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public static boolean logicalAnd(boolean a, boolean b) {
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return a && b;
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}
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/**
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* Returns the result of applying the logical OR operator to the
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* specified {@code boolean} operands.
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*
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* @param a the first operand
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* @param b the second operand
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* @return the logical OR of {@code a} and {@code b}
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* @see java.util.function.BinaryOperator
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* @since 1.8
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*/
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public static boolean logicalOr(boolean a, boolean b) {
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return a || b;
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}
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/**
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* Returns the result of applying the logical XOR operator to the
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* specified {@code boolean} operands.
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*
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* @param a the first operand
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* @param b the second operand
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* @return the logical XOR of {@code a} and {@code b}
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* @see java.util.function.BinaryOperator
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* @since 1.8
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*/
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public static boolean logicalXor(boolean a, boolean b) {
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return a ^ b;
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}
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}
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