Java 1.2 How-To/JavaHowTo.iso/3rdParty/jbuilder/unsupported/JDK1.2beta3/SOURCE/SRC.ZIP/java/lang/Boolean.java

Java Source | 1998-03-20 | 5.3 KB | 166 lines

/*
 * @(#)Boolean.java    1.28 98/03/18
 *
 * Copyright 1994-1997 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */

package java.lang;

/**
 * The Boolean class wraps a value of the primitive type
 * <code>boolean</code> in an object. An object of type
 * <code>Boolean</code> contains a single field whose type is
 * <code>boolean</code>.
 * <p>
 * In addition, this class provides many methods for
 * converting a <code>boolean</code> to a <code>String</code> and a
 * <code>String</code> to a <code>boolean</code>, as well as other
 * constants and methods useful when dealing with a
 * <code>boolean</code>.
 *
 * @author  Arthur van Hoff
 * @version 1.28, 03/18/98
 * @since   JDK1.0
 */
public final
class Boolean implements java.io.Serializable {
    /**
     * The <code>Boolean</code> object corresponding to the primitive
     * value <code>true</code>.
     */
    public static final Boolean TRUE = new Boolean(true);

    /**
     * The <code>Boolean</code> object corresponding to the primitive
     * value <code>false</code>.
     */
    public static final Boolean FALSE = new Boolean(false);

    /**
     * The Class object representing the primitive type boolean.
     *
     * @since   JDK1.1
     */
    public static final Class    TYPE = Class.getPrimitiveClass("boolean");

    /**
     * The value of the Boolean.
     */
    private boolean value;

    /** use serialVersionUID from JDK 1.0.2 for interoperability */
    private static final long serialVersionUID = -3665804199014368530L;

    /**
     * Allocates a <code>Boolean</code> object representing the
     * <code>value</code> argument.
     *
     * @param   value   the value of the <code>Boolean</code>.
     */
    public Boolean(boolean value) {
    this.value = value;
    }

    /**
     * Allocates a <code>Boolean</code> object representing the value
     * <code>true</code> if the string argument is not <code>null</code>
     * and is equal, ignoring case, to the string <code>"true"</code>.
     * Otherwise, allocate a <code>Boolean</code> object representing the
     * value <code>false</code>.
     *
     * @param   s   the string to be converted to a <code>Boolean</code>.
     */
    public Boolean(String s) {
    this(toBoolean(s));
    }

    /**
     * Returns the value of this Boolean object as a boolean.
     *
     * @return  the primitive <code>boolean</code> value of this object.
     */
    public boolean booleanValue() {
    return value;
    }

    /**
     * Returns the boolean value represented by the specified String.
     * A new <code>Boolean</code> object is constructed. This
     * <code>Boolean</code> contains the value <code>true</code> if the
     * string argument is not <code>null</code> and is equal, ignoring
     * case, to the string <code>"true"</code>.
     *
     * @param   s   a string.
     * @return  the <code>Boolean</code> value represented by the string.
     */
    public static Boolean valueOf(String s) {
    return new Boolean(toBoolean(s));
    }

    /**
     * Returns a String object representing this Boolean's value.
     * If this object contains the value <code>true</code>, a string equal
     * to <code>"true"</code> is returned. Otherwise, a string equal to
     * <code>"false"</code> is returned.
     *
     * @return  a string representation of this object.
     */
    public String toString() {
    return value ? "true" : "false";
    }

    /**
     * Returns a hash code for this Boolean.
     *
     * @return  a hash code value for this object.
     */
    public int hashCode() {
    return value ? 1231 : 1237;
    }

    /**
     * Returns <code>true</code> if and only if the argument is not
     * <code>null</code> and is a <code>Boolean </code>object that
     * contains the same <code>boolean</code> value as this object.
     *
     * @param   obj   the object to compare with.
     * @return  <code>true</code> if the objects are the same;
     *          <code>false</code> otherwise.
     */
    public boolean equals(Object obj) {
    if ((obj != null) && (obj instanceof Boolean)) {
        return value == ((Boolean)obj).booleanValue();
    }
    return false;
    }

    /**
     * Returns is <code>true</code> if and only if the system property
     * named by the argument exists and is equal to the string
     * <code>"true"</code>. (Beginning with Java 1.0.2, the test of
     * this string is case insensitive.) A system property is accessible
     * through <code>getProperty</code>, a method defined by the
     * <code>System</code> class.
     *
     * @param   name   the system property name.
     * @return  the <code>boolean</code> value of the system property.
     * @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) {
    return toBoolean(System.getProperty(name));
    }

    private static boolean toBoolean(String name) {
    return ((name != null) && name.toLowerCase().equals("true"));
    }
}