double.java

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/* Double.java -- object wrapper for double primitive
   Copyright (C) 1998, 1999, 2000, 2001, 2002 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., 59 Temple Place, Suite 330, Boston, MA
02111-1307 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 gnu.classpath.Configuration;

/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
 * "The Java Language Specification", ISBN 0-201-63451-1
 * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
 * Status:  Believed complete and correct.
 */

/**
 * Instances of class <code>Double</code> represent primitive
 * <code>double</code> values.
 *
 * Additionally, this class provides various helper functions and variables
 * related to doubles.
 *
 * @author Paul Fisher
 * @author Andrew Haley <[e-mail]>
 * @since JDK 1.0
 */
public final class Double extends Number implements Comparable
{
  /**
   * The minimum positive value a <code>double</code> may represent
   * is 5e-324.
   */
  public static final double MIN_VALUE = 5e-324;

  /**
   * The maximum positive value a <code>double</code> may represent
   * is 1.7976931348623157e+308.
   */
  public static final double MAX_VALUE = 1.7976931348623157e+308;

  /**
   * The value of a double representation -1.0/0.0, negative
   * infinity.  
   */
  public static final double NEGATIVE_INFINITY = -1.0d/0.0d;

  /**
   * The value of a double representing 1.0/0.0, positive infinity.
   */
  public static final double POSITIVE_INFINITY = 1.0d/0.0d;

  /**
   * All IEEE 754 values of NaN have the same value in Java.
   */
  public static final double NaN = 0.0d/0.0d;

  /**
   * The primitive type <code>double</code> is represented by this
   * <code>Class</code> object.
   */
  public static final Class TYPE = VMClassLoader.getPrimitiveClass('D');

  /**
   * The immutable value of this Double.
   */
  private final double value;

  private static final long serialVersionUID = -9172774392245257468L;

  /**
   * Load native routines necessary for this class.  
   */
  static
  {
    if (Configuration.INIT_LOAD_LIBRARY)
      {
	System.loadLibrary ("javalang");
	initIDs ();
      }
  }

  /**
   * Create a <code>Double</code> from the primitive <code>double</code>
   * specified.
   *
   * @param value the <code>double</code> argument
   */
  public Double (double value)
  {
    this.value = value;
  }

  /**
   * Create a <code>Double</code> from the specified
   * <code>String</code>.
   *
   * This method calls <code>Double.parseDouble()</code>.
   *
   * @exception NumberFormatException when the <code>String</code> cannot
   *            be parsed into a <code>Float</code>.
   * @param s the <code>String</code> to convert
   * @see #parseDouble(java.lang.String) 
   */
  public Double (String s) throws NumberFormatException
  {
    value = parseDouble (s);
  }

  /**
   * Convert the <code>double</code> value of this <code>Double</code>
   * to a <code>String</code>.  This method calls
   * <code>Double.toString(double)</code> to do its dirty work.
   *
   * @return the <code>String</code> representation of this <code>Double</code>.
   * @see #toString(double)
   */
  public String toString ()
  {
    return toString (value);
  }

  /**
   * If the <code>Object</code> is not <code>null</code>, is an
   * <code>instanceof</code> <code>Double</code>, and represents
   * the same primitive <code>double</code> value return 
   * <code>true</code>.  Otherwise <code>false</code> is returned.
   * <p>
   * Note that there are two differences between <code>==</code> and
   * <code>equals()</code>. <code>0.0d == -0.0d</code> returns <code>true</code>
   * but <code>new Double(0.0d).equals(new Double(-0.0d))</code> returns
   * <code>false</code>. And <code>Double.NaN == Double.NaN</code> returns
   * <code>false</code>, but
   * <code>new Double(Double.NaN).equals(new Double(Double.NaN))</code> returns
   * <code>true</code>.
   *
   * @param obj the object to compare to
   * @return whether the objects are semantically equal.
   */
  public boolean equals (Object obj)
  {
    if (!(obj instanceof Double))
      return false;

    double d = ((Double) obj).value;

    // GCJ LOCAL: this implementation is probably faster than
    // Classpath's, especially once we inline doubleToLongBits.
    return doubleToLongBits (value) == doubleToLongBits (d);
    // END GCJ LOCAL
  }

  /**
   * The hashcode is the value of the expression: <br>
   * <br>
   * <code>(int)(v^(v>>>32))</code><br>
   * <br>
   * where v is defined by: <br>
   * <code>long v = Double.doubleToLongBits(this.longValue());</code><br>
   */
  public int hashCode ()
  {
    long v = doubleToLongBits (value);
    return (int) (v ^ (v >>> 32));
  }

  /**
   * Return the value of this <code>Double</code> when cast to an 
   * <code>int</code>.
   */
  public int intValue ()
  {
    return (int) value;
  }

  /**
   * Return the value of this <code>Double</code> when cast to a
   * <code>long</code>.
   */
  public long longValue ()
  {
    return (long) value;
  }

  /**
   * Return the value of this <code>Double</code> when cast to a
   * <code>float</code>.
   */
  public float floatValue ()
  {
    return (float) value;
  }

  /**
   * Return the primitive <code>double</code> value represented by this
   * <code>Double</code>.
   */
  public double doubleValue ()
  {
    return value;
  }

  /**
   * Return the result of calling <code>new Double(java.lang.String)</code>.
   *
   * @param s the <code>String</code> to convert to a <code>Double</code>.
   * @return a new <code>Double</code> representing the <code>String</code>'s
   *         numeric value.
   *
   * @exception NullPointerException thrown if <code>String</code> is 
   * <code>null</code>.
   * @exception NumberFormatException thrown if <code>String</code> cannot
   * be parsed as a <code>double</code>.
   * @see #Double(java.lang.String)
   * @see #parseDouble(java.lang.String)
   */
  public static Double valueOf (String s) throws NumberFormatException
  {
    return new Double (s);
  }

  /**
   * Return <code>true</code> if the value of this <code>Double</code>
   * is the same as <code>NaN</code>, otherwise return <code>false</code>.
   * @return whether this <code>Double</code> is <code>NaN</code>.
   */
  public boolean isNaN ()
  {
    return isNaN (value);
  }

  /**
   * Return <code>true</code> if the <code>double</code> has the same