nullwritable.java

来自「Hadoop是一个用于运行应用程序在大型集群的廉价硬件设备上的框架。Hadoop」· Java 代码 · 共 35 行

/**
 * Copyright 2005 The Apache Software Foundation
 *
 * Licensed 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 org.apache.hadoop.io;

import java.io.*;

/** Singleton Writable with no data. */
public class NullWritable implements Writable {

  private static final NullWritable THIS = new NullWritable();

  private NullWritable() {}                       // no public ctor

  /** Returns the single instance of this class. */
  public static NullWritable get() { return THIS; }

  public void readFields(DataInput in) throws IOException {}
  public void write(DataOutput out) throws IOException {}
}