Java tutorial
/** * 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.hadoop.io; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.classification.InterfaceStability; /** A WritableComparable for ints. */ @InterfaceAudience.Public @InterfaceStability.Stable public class IntWritable implements WritableComparable<IntWritable> { private int value; public IntWritable() { } public IntWritable(int value) { set(value); } /** Set the value of this IntWritable. */ public void set(int value) { this.value = value; } /** Return the value of this IntWritable. */ public int get() { return value; } @Override public void readFields(DataInput in) throws IOException { value = in.readInt(); } @Override public void write(DataOutput out) throws IOException { out.writeInt(value); } /** Returns true iff <code>o</code> is a IntWritable with the same value. */ @Override public boolean equals(Object o) { if (!(o instanceof IntWritable)) return false; IntWritable other = (IntWritable) o; return this.value == other.value; } @Override public int hashCode() { return value; } /** Compares two IntWritables. */ @Override public int compareTo(IntWritable o) { int thisValue = this.value; int thatValue = o.value; return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1)); } @Override public String toString() { return Integer.toString(value); } /** A Comparator optimized for IntWritable. */ public static class Comparator extends WritableComparator { public Comparator() { super(IntWritable.class); } @Override public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) { int thisValue = readInt(b1, s1); int thatValue = readInt(b2, s2); return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1)); } } static { // register this comparator WritableComparator.define(IntWritable.class, new Comparator()); } }