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  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