mapreduce/src/contrib/streaming/src/test/org/apache/hadoop/streaming/UniqApp.java

/**
 * 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 org.apache.hadoop.streaming;

import java.io.*;
import java.util.Date;

/** A minimal Java implementation of /usr/bin/uniq
    Used to test the usage of external applications without adding
    platform-specific dependencies.
    Uniques lines and prepends a header on the line.
 */
public class UniqApp
{

  public UniqApp(String header)
  {
    this.header = header;
  }
  public void go() throws IOException
  {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String line;
    String prevLine = null;
    while ((line = in.readLine()) != null) {
      if (!line.equals(prevLine)) {
        System.out.println(header + line);
      }
      prevLine = line;
    }
  }

  public static void main(String[] args) throws IOException
  {
    String h = (args.length < 1) ? "" : args[0];
    UniqApp app = new UniqApp(h);
    app.go();
  }

  String header;
}