code: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.lang.mutable;
  
  import org.apache.commons.lang.math.NumberUtils;
  
  /**
   * A mutable <code>double</code> wrapper.
   * 
   * @see Double
   * @since 2.1
   * @version $Id: MutableDouble.java 437554 2006-08-28 06:21:41Z bayard $
   */
  public class MutableDouble extends Number implements Comparable, Mutable {
  
      /**
       * Required for serialization support.
       * 
       * @see java.io.Serializable
       */
      private static final long serialVersionUID = 1587163916L;
  
      /** The mutable value. */
      private double value;
  
      /**
       * Constructs a new MutableDouble with the default value of zero.
       */
      public MutableDouble() {
          super();
      }
  
      /**
       * Constructs a new MutableDouble with the specified value.
       * 
       * @param value
       *            a value.
       */
      public MutableDouble(double value) {
          super();
          this.value = value;
      }
  
      /**
       * Constructs a new MutableDouble with the specified value.
       * 
       * @param value
       *            a value.
       * @throws NullPointerException
       *             if the object is null
       */
      public MutableDouble(Number value) {
          super();
          this.value = value.doubleValue();
      }
  
      //-----------------------------------------------------------------------
      /**
       * Gets the value as a Double instance.
       * 
       * @return the value as a Double
       */
      public Object getValue() {
          return new Double(this.value);
      }
  
      /**
       * Sets the value.
       * 
       * @param value
       *            the value to set
       */
      public void setValue(double value) {
          this.value = value;
      }
  
      /**
       * Sets the value from any Number instance.
       * 
       * @param value
       *            the value to set
       * @throws NullPointerException
       *             if the object is null
       * @throws ClassCastException
       *             if the type is not a {@link Number}
       */
      public void setValue(Object value) {
          setValue(((Number) value).doubleValue());
      }
  
      //-----------------------------------------------------------------------
      // shortValue and bytValue rely on Number implementation
      /**
       * Returns the value of this MutableDouble as a int.
       *
       * @return the numeric value represented by this object after conversion to type int.
       */
      public int intValue() {
          return (int) value;
      }
  
      /**
       * Returns the value of this MutableDouble as a long.
       *
       * @return the numeric value represented by this object after conversion to type long.
       */
      public long longValue() {
          return (long) value;
      }
  
      /**
       * Returns the value of this MutableDouble as a float.
       *
       * @return the numeric value represented by this object after conversion to type float.
       */
      public float floatValue() {
          return (float) value;
      }
  
      /**
       * Returns the value of this MutableDouble as a double.
       *
       * @return the numeric value represented by this object after conversion to type double.
       */
      public double doubleValue() {
          return value;
      }
  
      /**
       * Checks whether the double value is the special NaN value.
       * 
       * @return true if NaN
       */
      public boolean isNaN() {
          return Double.isNaN(value);
      }
  
      /**
       * Checks whether the double value is infinite.
       * 
       * @return true if infinite
       */
      public boolean isInfinite() {
          return Double.isInfinite(value);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Gets this mutable as an instance of Double.
       *
       * @return a Double instance containing the value from this mutable
       */
      public Double toDouble() {
          return new Double(doubleValue());
      }
  
      //-----------------------------------------------------------------------
      /**
       * Increments the value.
       *
       * @since Commons Lang 2.2
       */
      public void increment() {
          value++;
      }
  
      /**
       * Decrements the value.
       *
       * @since Commons Lang 2.2
       */
      public void decrement() {
          value--;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Adds a value.
       * 
       * @param operand
       *            the value to add
       *
       * @since Commons Lang 2.2
       */
      public void add(double operand) {
          this.value += operand;
      }
  
      /**
       * Adds a value.
       * 
       * @param operand
       *            the value to add
       * @throws NullPointerException
       *             if the object is null
       *
       * @since Commons Lang 2.2
       */
      public void add(Number operand) {
          this.value += operand.doubleValue();
      }
  
      /**
       * Subtracts a value.
       * 
       * @param operand
       *            the value to add
       *
       * @since Commons Lang 2.2
       */
      public void subtract(double operand) {
          this.value -= operand;
      }
  
      /**
       * Subtracts a value.
       * 
       * @param operand
       *            the value to add
       * @throws NullPointerException
       *             if the object is null
       *
       * @since Commons Lang 2.2
       */
      public void subtract(Number operand) {
          this.value -= operand.doubleValue();
      }
  
      //-----------------------------------------------------------------------
      /**
       * Compares this object against the specified object. The result is <code>true</code> if and only if the argument
       * is not <code>null</code> and is a <code>Double</code> object that represents a double that has the identical
       * bit pattern to the bit pattern of the double represented by this object. For this purpose, two
       * <code>double</code> values are considered to be the same if and only if the method
       * {@link Double#doubleToLongBits(double)}returns the same long value when applied to each.
       * <p>
       * Note that in most cases, for two instances of class <code>Double</code>,<code>d1</code> and <code>d2</code>,
       * the value of <code>d1.equals(d2)</code> is <code>true</code> if and only if <blockquote>
       * 
       * <pre>
       *   d1.doubleValue()&nbsp;== d2.doubleValue()
       * </pre>
       * 
       * </blockquote>
       * <p>
       * also has the value <code>true</code>. However, there are two exceptions:
       * <ul>
       * <li>If <code>d1</code> and <code>d2</code> both represent <code>Double.NaN</code>, then the
       * <code>equals</code> method returns <code>true</code>, even though <code>Double.NaN==Double.NaN</code> has
       * the value <code>false</code>.
       * <li>If <code>d1</code> represents <code>+0.0</code> while <code>d2</code> represents <code>-0.0</code>,
       * or vice versa, the <code>equal</code> test has the value <code>false</code>, even though
       * <code>+0.0==-0.0</code> has the value <code>true</code>. This allows hashtables to operate properly.
       * </ul>
       * 
       * @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) {
          return (obj instanceof MutableDouble)
              && (Double.doubleToLongBits(((MutableDouble) obj).value) == Double.doubleToLongBits(value));
      }
  
      /**
       * Returns a suitable hashcode for this mutable.
       * 
       * @return a suitable hashcode
       */
      public int hashCode() {
          long bits = Double.doubleToLongBits(value);
          return (int) (bits ^ (bits >>> 32));
      }
  
      /**
       * Compares this mutable to another in ascending order.
       * 
       * @param obj
       *            the mutable to compare to
       * @return negative if this is less, zero if equal, positive if greater
       * @throws ClassCastException if the argument is not a MutableDouble
       */
      public int compareTo(Object obj) {
          MutableDouble other = (MutableDouble) obj;
          double anotherVal = other.value;
          return NumberUtils.compare(value, anotherVal);
      }
  
      /**
       * Returns the String value of this mutable.
       * 
       * @return the mutable value as a string
       */
      public String toString() {
          return String.valueOf(value);
      }
  
  }
  