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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