Close stream in finally : finally « Language Basics « Java

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Close stream in finally

 
/*
 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit http://www.davidflanagan.com/javaexamples3.
 */
//package je3.nio;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.WritableByteChannel;

/**
 * FileCopy2.java: this program copies the file named in its first argument to
 * the file named in its second argument, or to standard output if there is no
 * second argument.
 */
public class FileCopy2 {
  public static void main(String[] args) {
    FileInputStream fin = null; // Streams to the two files.
    FileOutputStream fout = null; // These are closed in the finally block.
    try {
      // Open a stream to for the input file and get a channel from it
      fin = new FileInputStream(args[0]);
      FileChannel in = fin.getChannel();

      // Now get the output channel
      WritableByteChannel out;
      if (args.length > 1) { // If there is a second filename
        fout = new FileOutputStream(args[1]); // open file stream
        out = fout.getChannel(); // get its channel
      } else { // There is no destination filename
        out = Channels.newChannel(System.out); // wrap stdout stream
      }

      // Query the size of the input file
      long numbytes = in.size();

      // Bulk-transfer all bytes from one channel to the other.
      // This is a special feature of FileChannel channels.
      // See also FileChannel.transferFrom()
      in.transferTo(0, numbytes, out);
    } catch (IOException e) {
      // IOExceptions usually have useful informative messages.
      // Display the message if anything goes wrong.
      System.out.println(e);
    } finally {
      // Always close input and output streams. Doing this closes
      // the channels associated with them as well.
      try {
        if (fin != null)
          fin.close();
        if (fout != null)
          fout.close();
      } catch (IOException e) {
      }
    }
  }
}

 

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