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
   * <p>
   * http://www.apache.org/licenses/LICENSE-2.0
   * <p>
   * 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;
  
  /**
   * ShortWritable 提供了 smallint 的 {@link Writable} 和 {@link WritableComparable} 的实现
   */
  public class ShortWritable implements WritableComparable<ShortWritable> {
  
    private short value;
  
    /*
    * 默认构造值为零的 ShortWritable
    */
    public ShortWritable() {
    }
  
    /*
    * 构造 smallint 值为给定的value 的 ShortWritable
    *
    * @param value
    */
    public ShortWritable(short value) {
      this.value = value;
    }
  
  
    /**
     * 序列化到指定的 {@link DataOutput} out.
     *
     * @param out
     * @throws IOException
     */
    @Override
    public void write(DataOutput out) throws IOException {
      out.writeShort(this.value);
    }
  
    /**
     * 从指定的 {@link DataInput} in 反序列化.
     *
     * @param in
     * @throws IOException
     */
    @Override
    public void readFields(DataInput in) throws IOException {
      this.value = in.readShort();
    }
  
    /**
     * 判断两个 ShortWritable 是否相等.
     *
     * 如果两个都是 ShortWritable 且值相等，返回true，否则返回false
     *
     * @param o
     * @return
     */
    @Override
    public boolean equals(Object o) {
      if (o.getClass() != getClass()) {
        return false;
      }
  
      return this.value == ((ShortWritable) o).value;
    }
  
    /**
     * 计算哈希值，直接返回此 ShortWritable 的值.
     */
    @Override
    public int hashCode() {
      return value;
    }
  
    @Override
    public String toString() {
      return Short.toString(value);
    }
  
    /**
     * 比较两个 ShortWritable 的值.
     *
     * @param o
     *     比较对象
     * @return (this < o ? -1 : (this == o) ? 0 ：1))
     */
    @Override
    public int compareTo(ShortWritable o) {
      return (this.value < o.value ? -1 : (this.value == o.value ? 0 : 1));
    }
  
    /*
    * 返回 ShortWritable 的值
    *
    * @return
    */
    public short get() {
      return value;
    }
  
    /*
    * 设置 ShortWritable 的值
    *
    * @param value
    */
    public void set(short value) {
      this.value = value;
    }
  
    /**
     * ShortWritable 对象的 {@link WritableComparator} 自然顺序实现（升序）.
     */
    public static class Comparator extends WritableComparator {
  
      public Comparator() {
        super(ShortWritable.class);
      }
  
      /**
       * 基于二进制内容的 ShortWritable 对象比较函数.
       */
      @Override
      public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
        short thisValue = readShort(b1, s1);
        short thatValue = readShort(b2, s2);
        return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
      }
    }
  
    static { // register this comparator
      WritableComparator.define(ShortWritable.class, new Comparator());
    }
  }
  