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