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; 020 021 022import java.io.DataInput; 023import java.io.DataOutput; 024import java.io.IOException; 025 026import org.apache.hadoop.classification.InterfaceAudience; 027import org.apache.hadoop.classification.InterfaceStability; 028 029/** A WritableComparable for longs. */ 030@InterfaceAudience.Public 031@InterfaceStability.Stable 032public class LongWritable implements WritableComparable<LongWritable> { 033 private long value; 034 035 public LongWritable() {} 036 037 public LongWritable(long value) { set(value); } 038 039 /** Set the value of this LongWritable. */ 040 public void set(long value) { this.value = value; } 041 042 /** Return the value of this LongWritable. */ 043 public long get() { return value; } 044 045 public void readFields(DataInput in) throws IOException { 046 value = in.readLong(); 047 } 048 049 public void write(DataOutput out) throws IOException { 050 out.writeLong(value); 051 } 052 053 /** Returns true iff <code>o</code> is a LongWritable with the same value. */ 054 public boolean equals(Object o) { 055 if (!(o instanceof LongWritable)) 056 return false; 057 LongWritable other = (LongWritable)o; 058 return this.value == other.value; 059 } 060 061 public int hashCode() { 062 return (int)value; 063 } 064 065 /** Compares two LongWritables. */ 066 public int compareTo(LongWritable o) { 067 long thisValue = this.value; 068 long thatValue = o.value; 069 return (thisValue<thatValue ? -1 : (thisValue==thatValue ? 0 : 1)); 070 } 071 072 public String toString() { 073 return Long.toString(value); 074 } 075 076 /** A Comparator optimized for LongWritable. */ 077 public static class Comparator extends WritableComparator { 078 public Comparator() { 079 super(LongWritable.class); 080 } 081 082 public int compare(byte[] b1, int s1, int l1, 083 byte[] b2, int s2, int l2) { 084 long thisValue = readLong(b1, s1); 085 long thatValue = readLong(b2, s2); 086 return (thisValue<thatValue ? -1 : (thisValue==thatValue ? 0 : 1)); 087 } 088 } 089 090 /** A decreasing Comparator optimized for LongWritable. */ 091 public static class DecreasingComparator extends Comparator { 092 093 @Override 094 public int compare(WritableComparable a, WritableComparable b) { 095 return -super.compare(a, b); 096 } 097 public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) { 098 return -super.compare(b1, s1, l1, b2, s2, l2); 099 } 100 } 101 102 static { // register default comparator 103 WritableComparator.define(LongWritable.class, new Comparator()); 104 } 105 106} 107