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/**
 * 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;

/**
 * IntWritable 提供了 int 的 {@link Writable} 和 {@link WritableComparable} 的实现
 */
@SuppressWarnings("rawtypes")
public class IntWritable implements WritableComparable {

  private int value;

  /**
   * 默认构造int 值为0的 IntWritable.
   */
  public IntWritable() {
  }

  /**
   * 构造int 值为给定 value 的 IntWritable.
   *
   * @param value
   */
  public IntWritable(int value) {
    set(value);
  }

  /**
   * 设置 IntWritable 的值
   *
   * @param value
   */
  public void set(int value) {
    this.value = value;
  }

  /**
   * 返回此 IntWritable 的值
   *
   * @return
   */
  public int get() {
    return value;
  }

  @Override
  public void readFields(DataInput in) throws IOException {
    value = in.readInt();
  }

  @Override
  public void write(DataOutput out) throws IOException {
    out.writeInt(value);
  }

  /**
   * 判断两个 IntWritable 是否相等.
   *
   * 

* 如果两个都是 IntWritable 且值相等,返回true,否则返回false * * @param o * @return */ @Override public boolean equals(Object o) { if (!(o instanceof IntWritable)) { return false; } IntWritable other = (IntWritable) o; return this.value == other.value; } /** * 计算哈希值,直接返回此 IntWritable 的值. */ @Override public int hashCode() { return value; } /** * 比较两个 IntWritable 的值. * * @param o * 比较对象 * @return (this < o ? -1 : (this == o) ? 0 :1)) */ @Override public int compareTo(Object o) { int thisValue = this.value; int thatValue = ((IntWritable) o).value; return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1)); } @Override public String toString() { return Integer.toString(value); } /** * IntWritable 对象的 {@link WritableComparator} 自然顺序实现(升序). */ public static class Comparator extends WritableComparator { public Comparator() { super(IntWritable.class); } /** * 基于二进制内容的 IntWritable 对象比较函数. */ @Override public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) { int thisValue = readInt(b1, s1); int thatValue = readInt(b2, s2); return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1)); } } static { // register this comparator WritableComparator.define(IntWritable.class, new Comparator()); } }





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