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.*;
022
023import org.apache.hadoop.classification.InterfaceAudience;
024import org.apache.hadoop.classification.InterfaceStability;
025
026/** A WritableComparable for a single byte. */
027@InterfaceAudience.Public
028@InterfaceStability.Stable
029public 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  @Override
043  public void readFields(DataInput in) throws IOException {
044    value = in.readByte();
045  }
046
047  @Override
048  public void write(DataOutput out) throws IOException {
049    out.writeByte(value);
050  }
051
052  /** Returns true iff <code>o</code> is a ByteWritable with the same value. */
053  @Override
054  public boolean equals(Object o) {
055    if (!(o instanceof ByteWritable)) {
056      return false;
057    }
058    ByteWritable other = (ByteWritable)o;
059    return this.value == other.value;
060  }
061
062  @Override
063  public int hashCode() {
064    return (int)value;
065  }
066
067  /** Compares two ByteWritables. */
068  @Override
069  public int compareTo(ByteWritable o) {
070    int thisValue = this.value;
071    int thatValue = o.value;
072    return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
073  }
074
075  @Override
076  public String toString() {
077    return Byte.toString(value);
078  }
079
080  /** A Comparator optimized for ByteWritable. */ 
081  public static class Comparator extends WritableComparator {
082    public Comparator() {
083      super(ByteWritable.class);
084    }
085
086    @Override
087    public int compare(byte[] b1, int s1, int l1,
088                       byte[] b2, int s2, int l2) {
089      byte thisValue = b1[s1];
090      byte thatValue = b2[s2];
091      return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
092    }
093  }
094
095  static {                                        // register this comparator
096    WritableComparator.define(ByteWritable.class, new Comparator());
097  }
098}
099