Boolean.java

/* Boolean.java -- object wrapper for boolean
   Copyright (C) 1998, 2001, 2002, 2004, 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath 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 for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package java.lang;

import java.io.Serializable;

/**
 * Instances of class <code>Boolean</code> represent primitive
 * <code>boolean</code> values.
 *
 * @author Paul Fisher
 * @author Eric Blake (ebb9@email.byu.edu)
 * @since 1.0
 * @status updated to 1.5
 */
public final class Boolean implements Serializable, Comparable<Boolean>
{
  /**
   * Compatible with JDK 1.0.2+.
   */
  private static final long serialVersionUID = -3665804199014368530L;

  /**
   * This field is a <code>Boolean</code> object representing the
   * primitive value <code>true</code>. This instance is returned
   * by the static <code>valueOf()</code> methods if they return
   * a <code>Boolean</code> representing <code>true</code>.
   */
  public static final Boolean TRUE = new Boolean(true);

  /**
   * This field is a <code>Boolean</code> object representing the
   * primitive value <code>false</code>. This instance is returned
   * by the static <code>valueOf()</code> methods if they return
   * a <code>Boolean</code> representing <code>false</code>.
   */
  public static final Boolean FALSE = new Boolean(false);

  /**
   * The primitive type <code>boolean</code> is represented by this
   * <code>Class</code> object.
   *
   * @since 1.1
   */
  public static final Class<Boolean> TYPE = (Class<Boolean>) VMClassLoader.getPrimitiveClass('Z');

  /**
   * The immutable value of this Boolean.
   * @serial the wrapped value
   */
  private final boolean value;

  /**
   * Create a <code>Boolean</code> object representing the value of the
   * argument <code>value</code>. In general the use of the static
   * method <code>valueof(boolean)</code> is more efficient since it will
   * not create a new object.
   *
   * @param value the primitive value of this <code>Boolean</code>
   * @see #valueOf(boolean)
   */
  public Boolean(boolean value)
  {
    this.value = value;
  }

  /**
   * Creates a <code>Boolean</code> object representing the primitive
   * <code>true</code> if and only if <code>s</code> matches
   * the string "true" ignoring case, otherwise the object will represent
   * the primitive <code>false</code>. In general the use of the static
   * method <code>valueof(String)</code> is more efficient since it will
   * not create a new object.
   *
   * @param s the <code>String</code> representation of <code>true</code>
   *        or false
   */
  public Boolean(String s)
  {
    value = "true".equalsIgnoreCase(s);
  }

  /**
   * Return the primitive <code>boolean</code> value of this
   * <code>Boolean</code> object.
   *
   * @return true or false, depending on the value of this Boolean
   */
  public boolean booleanValue()
  {
    return value;
  }

  /**
   * Returns the Boolean <code>TRUE</code> if the given boolean is
   * <code>true</code>, otherwise it will return the Boolean
   * <code>FALSE</code>.
   *
   * @param b the boolean to wrap
   * @return the wrapper object
   * @see #TRUE
   * @see #FALSE
   * @since 1.4
   */
  public static Boolean valueOf(boolean b)
  {
    return b ? TRUE : FALSE;
  }

  /**
   * Returns the Boolean <code>TRUE</code> if and only if the given
   * String is equal, ignoring case, to the the String "true", otherwise
   * it will return the Boolean <code>FALSE</code>.
   *
   * @param s the string to convert
   * @return a wrapped boolean from the string
   */
  public static Boolean valueOf(String s)
  {
    return "true".equalsIgnoreCase(s) ? TRUE : FALSE;
  }

  /**
   * Returns "true" if the value of the give boolean is <code>true</code> and
   * returns "false" if the value of the given boolean is <code>false</code>.
   *
   * @param b the boolean to convert
   * @return the string representation of the boolean
   * @since 1.4
   */
  public static String toString(boolean b)
  {
    return b ? "true" : "false";
  }

  /**
   * Returns "true" if the value of this object is <code>true</code> and
   * returns "false" if the value of this object is <code>false</code>.
   *
   * @return the string representation of this
   */
  public String toString()
  {
    return value ? "true" : "false";
  }

  /**
   * Returns the integer <code>1231</code> if this object represents
   * the primitive <code>true</code> and the integer <code>1237</code>
   * otherwise.
   *
   * @return the hash code
   */
  public int hashCode()
  {
    return value ? 1231 : 1237;
  }

  /**
   * If the <code>obj</code> is an instance of <code>Boolean</code> and
   * has the same primitive value as this object then <code>true</code>
   * is returned.  In all other cases, including if the <code>obj</code>
   * is <code>null</code>, <code>false</code> is returned.
   *
   * @param obj possibly an instance of any <code>Class</code>
   * @return true if <code>obj</code> equals this
   */
  public boolean equals(Object obj)
  {
    return obj instanceof Boolean && value == ((Boolean) obj).value;
  }

  /**
   * If the value of the system property <code>name</code> matches
   * "true" ignoring case then the function returns <code>true</code>.
   *
   * @param name the property name to look up
   * @return true if the property resulted in "true"
   * @throws SecurityException if accessing the system property is forbidden
   * @see System#getProperty(String)
   */
  public static boolean getBoolean(String name)
  {
    if (name == null || "".equals(name))
      return false;
    return "true".equalsIgnoreCase(System.getProperty(name));
  }

  /**
   * Compares this Boolean to another.
   *
   * @param other the Boolean to compare this Boolean to
   * @return 0 if both Booleans represent the same value, a positive number
   * if this Boolean represents true and the other false, and a negative
   * number otherwise.
   * @since 1.5
   */
  public int compareTo(Boolean other)
  {
    return value == other.value ? 0 : (value ? 1 : -1);
  }

  /**
   * If the String argument is "true", ignoring case, return true.
   * Otherwise, return false.
   *
   * @param b String to parse
   * @since 1.5
   */
  public static boolean parseBoolean(String b)
  {
    return "true".equalsIgnoreCase(b) ? true : false;
  }

}