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
019 package org.apache.hadoop.io;
020
021 import java.io.DataInput;
022 import java.io.DataOutput;
023 import java.io.IOException;
024
025 import org.apache.hadoop.classification.InterfaceAudience;
026 import org.apache.hadoop.classification.InterfaceStability;
027
028 /**
029 * Writable for Double values.
030 */
031 @InterfaceAudience.Public
032 @InterfaceStability.Stable
033 public 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 public void readFields(DataInput in) throws IOException {
046 value = in.readDouble();
047 }
048
049 public void write(DataOutput out) throws IOException {
050 out.writeDouble(value);
051 }
052
053 public void set(double value) { this.value = value; }
054
055 public double get() { return value; }
056
057 /**
058 * Returns true iff <code>o</code> is a DoubleWritable with the same value.
059 */
060 @Override
061 public boolean equals(Object o) {
062 if (!(o instanceof DoubleWritable)) {
063 return false;
064 }
065 DoubleWritable other = (DoubleWritable)o;
066 return this.value == other.value;
067 }
068
069 @Override
070 public int hashCode() {
071 return (int)Double.doubleToLongBits(value);
072 }
073
074 @Override
075 public int compareTo(DoubleWritable o) {
076 return (value < o.value ? -1 : (value == o.value ? 0 : 1));
077 }
078
079 @Override
080 public String toString() {
081 return Double.toString(value);
082 }
083
084 /** A Comparator optimized for DoubleWritable. */
085 public static class Comparator extends WritableComparator {
086 public Comparator() {
087 super(DoubleWritable.class);
088 }
089
090 @Override
091 public int compare(byte[] b1, int s1, int l1,
092 byte[] b2, int s2, int l2) {
093 double thisValue = readDouble(b1, s1);
094 double thatValue = readDouble(b2, s2);
095 return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
096 }
097 }
098
099 static { // register this comparator
100 WritableComparator.define(DoubleWritable.class, new Comparator());
101 }
102
103 }
104