001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.io;
020
021import java.io.DataInput;
022import java.io.DataOutput;
023import java.io.IOException;
024
025import org.apache.hadoop.classification.InterfaceAudience;
026import org.apache.hadoop.classification.InterfaceStability;
027
028/**
029 * Writable for Double values.
030 */
031@InterfaceAudience.Public
032@InterfaceStability.Stable
033public class DoubleWritable implements WritableComparable<DoubleWritable> {
034
035  private double value = 0.0;
036  
037  public DoubleWritable() {
038    
039  }
040  
041  public DoubleWritable(double value) {
042    set(value);
043  }
044  
045  @Override
046  public void readFields(DataInput in) throws IOException {
047    value = in.readDouble();
048  }
049
050  @Override
051  public void write(DataOutput out) throws IOException {
052    out.writeDouble(value);
053  }
054  
055  public void set(double value) { this.value = value; }
056  
057  public double get() { return value; }
058
059  /**
060   * Returns true iff <code>o</code> is a DoubleWritable with the same value.
061   */
062  @Override
063  public boolean equals(Object o) {
064    if (!(o instanceof DoubleWritable)) {
065      return false;
066    }
067    DoubleWritable other = (DoubleWritable)o;
068    return this.value == other.value;
069  }
070  
071  @Override
072  public int hashCode() {
073    return (int)Double.doubleToLongBits(value);
074  }
075  
076  @Override
077  public int compareTo(DoubleWritable o) {
078    return (value < o.value ? -1 : (value == o.value ? 0 : 1));
079  }
080  
081  @Override
082  public String toString() {
083    return Double.toString(value);
084  }
085
086  /** A Comparator optimized for DoubleWritable. */ 
087  public static class Comparator extends WritableComparator {
088    public Comparator() {
089      super(DoubleWritable.class);
090    }
091
092    @Override
093    public int compare(byte[] b1, int s1, int l1,
094                       byte[] b2, int s2, int l2) {
095      double thisValue = readDouble(b1, s1);
096      double thatValue = readDouble(b2, s2);
097      return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
098    }
099  }
100
101  static {                                        // register this comparator
102    WritableComparator.define(DoubleWritable.class, new Comparator());
103  }
104
105}
106