content: /**
   * 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 com.aliyun.odps.io;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  
  /**
   * LongWritable 提供了 long 的 {@link Writable} 和 {@link WritableComparable} 的实现
   */
  @SuppressWarnings("rawtypes")
  public class LongWritable implements WritableComparable {
  
    private long value;
  
    /**
     * 默认构造 long 值为0的 LongWritable.
     */
    public LongWritable() {
    }
  
    /**
     * 构造 long 值为给定 value 的 LongWritable.
     *
     * @param value
     */
    public LongWritable(long value) {
      set(value);
    }
  
    /**
     * 设置 LongWritable 的值
     *
     * @param value
     */
    public void set(long value) {
      this.value = value;
    }
  
    /**
     * 返回此 LongWritable 的值
     *
     * @return
     */
    public long get() {
      return value;
    }
  
    @Override
    public void readFields(DataInput in) throws IOException {
      value = in.readLong();
    }
  
    @Override
    public void write(DataOutput out) throws IOException {
      out.writeLong(value);
    }
  
    /**
     * 判断两个 LongWritable 是否相等.
     *
     * <p>
     * 如果两个都是 LongWritable 且值相等，返回true，否则返回false
     *
     * @param o
     * @return
     */
    @Override
    public boolean equals(Object o) {
      if (!(o instanceof LongWritable)) {
        return false;
      }
      LongWritable other = (LongWritable) o;
      return this.value == other.value;
    }
  
    /**
     * 计算哈希值，直接返回此 LongWritable 的值.
     */
    @Override
    public int hashCode() {
      return (int) value;
    }
  
    /**
     * 比较两个 LongWritable 的值.
     *
     * @param o
     *     比较对象
     * @return (this < o ? -1 : (this == o) ? 0 ：1))
     */
    @Override
    public int compareTo(Object o) {
      long thisValue = this.value;
      long thatValue = ((LongWritable) o).value;
      return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
    }
  
    @Override
    public String toString() {
      return Long.toString(value);
    }
  
    /**
     * LongWritable 对象的 {@link WritableComparator} 自然顺序实现（升序）.
     */
    public static class Comparator extends WritableComparator {
  
      public Comparator() {
        super(LongWritable.class);
      }
  
      /**
       * 基于二进制内容的 LongWritable 对象比较函数.
       */
      @Override
      public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
        long thisValue = readLong(b1, s1);
        long thatValue = readLong(b2, s2);
        return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
      }
    }
  
    /**
     * LongWritable 对象的 {@link WritableComparator} 降序实现.
     */
    public static class DecreasingComparator extends Comparator {
  
      @Override
      public int compare(WritableComparable a, WritableComparable b) {
        return -super.compare(a, b);
      }
  
      /**
       * 基于二进制内容的 LongWritable 对象比较函数.
       *
       * @return 对象1>对象2，返回-1，对象1=对象2，返回0，对象1<对象2，返回1
       */
      @Override
      public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
        return -super.compare(b1, s1, l1, b2, s2, l2);
      }
    }
  
    static { // register default comparator
      WritableComparator.define(LongWritable.class, new Comparator());
    }
  
  }
  