// newio/ChannelCopy.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
// Copying a file using channels and buffers
// {java ChannelCopy ChannelCopy.java test.txt}
import java.nio.*;
import java.nio.channels.*;
import java.io.*;

public class ChannelCopy {
  private static final int BSIZE = 1024;
  public static void
  main(String[] args) throws Exception {
    if(args.length != 2) {
      System.out.println(
        "arguments: sourcefile destfile");
      System.exit(1);
    }
    try(FileChannel in = new FileInputStream(
          args[0]).getChannel();
        FileChannel out = new FileOutputStream(
          args[1]).getChannel()) {
      ByteBuffer buffer = ByteBuffer.allocate(BSIZE);
      while(in.read(buffer) != -1) {
        buffer.flip(); // Prepare for writing
        out.write(buffer);
        buffer.clear();  // Prepare for reading
      }
    }
  }
}