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    
022    import java.io.DataInput;
023    import java.io.DataOutput;
024    import java.io.IOException;
025    
026    import org.apache.hadoop.classification.InterfaceAudience;
027    import org.apache.hadoop.classification.InterfaceStability;
028    
029    /** A WritableComparable for longs. */
030    @InterfaceAudience.Public
031    @InterfaceStability.Stable
032    public 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      @Override
046      public void readFields(DataInput in) throws IOException {
047        value = in.readLong();
048      }
049    
050      @Override
051      public void write(DataOutput out) throws IOException {
052        out.writeLong(value);
053      }
054    
055      /** Returns true iff <code>o</code> is a LongWritable with the same value. */
056      @Override
057      public boolean equals(Object o) {
058        if (!(o instanceof LongWritable))
059          return false;
060        LongWritable other = (LongWritable)o;
061        return this.value == other.value;
062      }
063    
064      @Override
065      public int hashCode() {
066        return (int)value;
067      }
068    
069      /** Compares two LongWritables. */
070      @Override
071      public int compareTo(LongWritable o) {
072        long thisValue = this.value;
073        long thatValue = o.value;
074        return (thisValue<thatValue ? -1 : (thisValue==thatValue ? 0 : 1));
075      }
076    
077      @Override
078      public String toString() {
079        return Long.toString(value);
080      }
081    
082      /** A Comparator optimized for LongWritable. */ 
083      public static class Comparator extends WritableComparator {
084        public Comparator() {
085          super(LongWritable.class);
086        }
087    
088        @Override
089        public int compare(byte[] b1, int s1, int l1,
090                           byte[] b2, int s2, int l2) {
091          long thisValue = readLong(b1, s1);
092          long thatValue = readLong(b2, s2);
093          return (thisValue<thatValue ? -1 : (thisValue==thatValue ? 0 : 1));
094        }
095      }
096    
097      /** A decreasing Comparator optimized for LongWritable. */ 
098      public static class DecreasingComparator extends Comparator {
099        
100        @Override
101        public int compare(WritableComparable a, WritableComparable b) {
102          return -super.compare(a, b);
103        }
104        @Override
105        public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
106          return -super.compare(b1, s1, l1, b2, s2, l2);
107        }
108      }
109    
110      static {                                       // register default comparator
111        WritableComparator.define(LongWritable.class, new Comparator());
112      }
113    
114    }
115