Compare the contents of two Streams to determine if they are equal or not. : InputStream « File « Java Tutorial

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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.
 */

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
/** * Origin of code: Apache Avalon (Excalibur)
 * 
 * @author Peter Donald
 * @author Jeff Turner
 * @author Matthew Hawthorne
 * @author Stephen Colebourne
 * @author Gareth Davis
 * @version CVS $Revision$ $Date$*/
public class Main {
  /**
   * Compare the contents of two Streams to determine if they are equal or not.
   * 
   * This method buffers the input internally using <code>BufferedInputStream</code> if they are
   * not already buffered.
   * 
   * @param input1
   *            the first stream
   * @param input2
   *            the second stream
   * @return true if the content of the streams are equal or they both don't exist, false
   *         otherwise
   * @throws NullPointerException
   *             if either input is null
   * @throws IOException
   *             if an I/O error occurs
   */
  public static boolean contentEquals(InputStream input1, InputStream input2) throws IOException
  {
    if (!(input1 instanceof BufferedInputStream))
    {
      input1 = new BufferedInputStream(input1);
    }
    if (!(input2 instanceof BufferedInputStream))
    {
      input2 = new BufferedInputStream(input2);
    }

    int ch = input1.read();
    while (-1 != ch)
    {
      int ch2 = input2.read();
      if (ch != ch2)
      {
        return false;
      }
      ch = input1.read();
    }

    int ch2 = input2.read();
    return (ch2 == -1);
  }
}