jdk/src/java.base/share/classes/java/lang/Boolean.java
changeset 25859 3317bb8137f4
parent 24865 09b1d992ca72
child 30678 a8b7fd8ede97
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.base/share/classes/java/lang/Boolean.java	Sun Aug 17 15:54:13 2014 +0100
@@ -0,0 +1,335 @@
+/*
+ * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.lang;
+
+/**
+ * The Boolean class wraps a value of the primitive type
+ * {@code boolean} in an object. An object of type
+ * {@code Boolean} contains a single field whose type is
+ * {@code boolean}.
+ * <p>
+ * In addition, this class provides many methods for
+ * converting a {@code boolean} to a {@code String} and a
+ * {@code String} to a {@code boolean}, as well as other
+ * constants and methods useful when dealing with a
+ * {@code boolean}.
+ *
+ * @author  Arthur van Hoff
+ * @since   1.0
+ */
+public final class Boolean implements java.io.Serializable,
+                                      Comparable<Boolean>
+{
+    /**
+     * The {@code Boolean} object corresponding to the primitive
+     * value {@code true}.
+     */
+    public static final Boolean TRUE = new Boolean(true);
+
+    /**
+     * The {@code Boolean} object corresponding to the primitive
+     * value {@code false}.
+     */
+    public static final Boolean FALSE = new Boolean(false);
+
+    /**
+     * The Class object representing the primitive type boolean.
+     *
+     * @since   1.1
+     */
+    @SuppressWarnings("unchecked")
+    public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");
+
+    /**
+     * The value of the Boolean.
+     *
+     * @serial
+     */
+    private final boolean value;
+
+    /** use serialVersionUID from JDK 1.0.2 for interoperability */
+    private static final long serialVersionUID = -3665804199014368530L;
+
+    /**
+     * Allocates a {@code Boolean} object representing the
+     * {@code value} argument.
+     *
+     * <p><b>Note: It is rarely appropriate to use this constructor.
+     * Unless a <i>new</i> instance is required, the static factory
+     * {@link #valueOf(boolean)} is generally a better choice. It is
+     * likely to yield significantly better space and time performance.</b>
+     *
+     * @param   value   the value of the {@code Boolean}.
+     */
+    public Boolean(boolean value) {
+        this.value = value;
+    }
+
+    /**
+     * Allocates a {@code Boolean} object representing the value
+     * {@code true} if the string argument is not {@code null}
+     * and is equal, ignoring case, to the string {@code "true"}.
+     * Otherwise, allocate a {@code Boolean} object representing the
+     * value {@code false}. Examples:<p>
+     * {@code new Boolean("True")} produces a {@code Boolean} object
+     * that represents {@code true}.<br>
+     * {@code new Boolean("yes")} produces a {@code Boolean} object
+     * that represents {@code false}.
+     *
+     * @param   s   the string to be converted to a {@code Boolean}.
+     */
+    public Boolean(String s) {
+        this(parseBoolean(s));
+    }
+
+    /**
+     * Parses the string argument as a boolean.  The {@code boolean}
+     * returned represents the value {@code true} if the string argument
+     * is not {@code null} and is equal, ignoring case, to the string
+     * {@code "true"}. <p>
+     * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
+     * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
+     *
+     * @param      s   the {@code String} containing the boolean
+     *                 representation to be parsed
+     * @return     the boolean represented by the string argument
+     * @since 1.5
+     */
+    public static boolean parseBoolean(String s) {
+        return ((s != null) && s.equalsIgnoreCase("true"));
+    }
+
+    /**
+     * Returns the value of this {@code Boolean} object as a boolean
+     * primitive.
+     *
+     * @return  the primitive {@code boolean} value of this object.
+     */
+    public boolean booleanValue() {
+        return value;
+    }
+
+    /**
+     * Returns a {@code Boolean} instance representing the specified
+     * {@code boolean} value.  If the specified {@code boolean} value
+     * is {@code true}, this method returns {@code Boolean.TRUE};
+     * if it is {@code false}, this method returns {@code Boolean.FALSE}.
+     * If a new {@code Boolean} instance is not required, this method
+     * should generally be used in preference to the constructor
+     * {@link #Boolean(boolean)}, as this method is likely to yield
+     * significantly better space and time performance.
+     *
+     * @param  b a boolean value.
+     * @return a {@code Boolean} instance representing {@code b}.
+     * @since  1.4
+     */
+    public static Boolean valueOf(boolean b) {
+        return (b ? TRUE : FALSE);
+    }
+
+    /**
+     * Returns a {@code Boolean} with a value represented by the
+     * specified string.  The {@code Boolean} returned represents a
+     * true value if the string argument is not {@code null}
+     * and is equal, ignoring case, to the string {@code "true"}.
+     *
+     * @param   s   a string.
+     * @return  the {@code Boolean} value represented by the string.
+     */
+    public static Boolean valueOf(String s) {
+        return parseBoolean(s) ? TRUE : FALSE;
+    }
+
+    /**
+     * Returns a {@code String} object representing the specified
+     * boolean.  If the specified boolean is {@code true}, then
+     * the string {@code "true"} will be returned, otherwise the
+     * string {@code "false"} will be returned.
+     *
+     * @param b the boolean to be converted
+     * @return the string representation of the specified {@code boolean}
+     * @since 1.4
+     */
+    public static String toString(boolean b) {
+        return b ? "true" : "false";
+    }
+
+    /**
+     * Returns a {@code String} object representing this Boolean's
+     * value.  If this object represents the value {@code true},
+     * a string equal to {@code "true"} is returned. Otherwise, a
+     * string equal to {@code "false"} is returned.
+     *
+     * @return  a string representation of this object.
+     */
+    public String toString() {
+        return value ? "true" : "false";
+    }
+
+    /**
+     * Returns a hash code for this {@code Boolean} object.
+     *
+     * @return  the integer {@code 1231} if this object represents
+     * {@code true}; returns the integer {@code 1237} if this
+     * object represents {@code false}.
+     */
+    @Override
+    public int hashCode() {
+        return Boolean.hashCode(value);
+    }
+
+    /**
+     * Returns a hash code for a {@code boolean} value; compatible with
+     * {@code Boolean.hashCode()}.
+     *
+     * @param value the value to hash
+     * @return a hash code value for a {@code boolean} value.
+     * @since 1.8
+     */
+    public static int hashCode(boolean value) {
+        return value ? 1231 : 1237;
+    }
+
+   /**
+     * Returns {@code true} if and only if the argument is not
+     * {@code null} and is a {@code Boolean} object that
+     * represents the same {@code boolean} value as this object.
+     *
+     * @param   obj   the object to compare with.
+     * @return  {@code true} if the Boolean objects represent the
+     *          same value; {@code false} otherwise.
+     */
+    public boolean equals(Object obj) {
+        if (obj instanceof Boolean) {
+            return value == ((Boolean)obj).booleanValue();
+        }
+        return false;
+    }
+
+    /**
+     * Returns {@code true} if and only if the system property
+     * named by the argument exists and is equal to the string
+     * {@code "true"}. (Beginning with version 1.0.2 of the
+     * Java<small><sup>TM</sup></small> platform, the test of
+     * this string is case insensitive.) A system property is accessible
+     * through {@code getProperty}, a method defined by the
+     * {@code System} class.
+     * <p>
+     * If there is no property with the specified name, or if the specified
+     * name is empty or null, then {@code false} is returned.
+     *
+     * @param   name   the system property name.
+     * @return  the {@code boolean} value of the system property.
+     * @throws  SecurityException for the same reasons as
+     *          {@link System#getProperty(String) System.getProperty}
+     * @see     java.lang.System#getProperty(java.lang.String)
+     * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
+     */
+    public static boolean getBoolean(String name) {
+        boolean result = false;
+        try {
+            result = parseBoolean(System.getProperty(name));
+        } catch (IllegalArgumentException | NullPointerException e) {
+        }
+        return result;
+    }
+
+    /**
+     * Compares this {@code Boolean} instance with another.
+     *
+     * @param   b the {@code Boolean} instance to be compared
+     * @return  zero if this object represents the same boolean value as the
+     *          argument; a positive value if this object represents true
+     *          and the argument represents false; and a negative value if
+     *          this object represents false and the argument represents true
+     * @throws  NullPointerException if the argument is {@code null}
+     * @see     Comparable
+     * @since  1.5
+     */
+    public int compareTo(Boolean b) {
+        return compare(this.value, b.value);
+    }
+
+    /**
+     * Compares two {@code boolean} values.
+     * The value returned is identical to what would be returned by:
+     * <pre>
+     *    Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
+     * </pre>
+     *
+     * @param  x the first {@code boolean} to compare
+     * @param  y the second {@code boolean} to compare
+     * @return the value {@code 0} if {@code x == y};
+     *         a value less than {@code 0} if {@code !x && y}; and
+     *         a value greater than {@code 0} if {@code x && !y}
+     * @since 1.7
+     */
+    public static int compare(boolean x, boolean y) {
+        return (x == y) ? 0 : (x ? 1 : -1);
+    }
+
+    /**
+     * Returns the result of applying the logical AND operator to the
+     * specified {@code boolean} operands.
+     *
+     * @param a the first operand
+     * @param b the second operand
+     * @return the logical AND of {@code a} and {@code b}
+     * @see java.util.function.BinaryOperator
+     * @since 1.8
+     */
+    public static boolean logicalAnd(boolean a, boolean b) {
+        return a && b;
+    }
+
+    /**
+     * Returns the result of applying the logical OR operator to the
+     * specified {@code boolean} operands.
+     *
+     * @param a the first operand
+     * @param b the second operand
+     * @return the logical OR of {@code a} and {@code b}
+     * @see java.util.function.BinaryOperator
+     * @since 1.8
+     */
+    public static boolean logicalOr(boolean a, boolean b) {
+        return a || b;
+    }
+
+    /**
+     * Returns the result of applying the logical XOR operator to the
+     * specified {@code boolean} operands.
+     *
+     * @param a the first operand
+     * @param b the second operand
+     * @return  the logical XOR of {@code a} and {@code b}
+     * @see java.util.function.BinaryOperator
+     * @since 1.8
+     */
+    public static boolean logicalXor(boolean a, boolean b) {
+        return a ^ b;
+    }
+}