/**
* 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;
/**
* WritableComparable 接口同时继承了 {@link Writable} 和 {@link Comparable}.
*
* <p>
* <code>WritableComparable</code>s 对象之间可以进行比较，{@link Mapper} 输出的 Key
* 都需要实现此接口用于排序.
* </p>
*
* <p>
* 代码示例:
*
* <pre>
* public class MyWritableComparable implements WritableComparable {
* // Some data
* private int counter;
* private long timestamp;
*
* public void write(DataOutput out) throws IOException {
* out.writeInt(counter);
* out.writeLong(timestamp);
* }
*
* public void readFields(DataInput in) throws IOException {
* counter = in.readInt();
* timestamp = in.readLong();
* }
*
* public int compareTo(MyWritableComparable w) {
* int thisValue = this.value;
* int thatValue = ((IntWritable) o).value;
* return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
* }
* }
* </pre>
*
* </p>
*/
public interface WritableComparable<T> extends Writable, Comparable<T> {
}