import java.nio.*;
import java.nio.channels.*;
import java.io.*;

public class FileChannelTest5 {

    public FileChannelTest5(String filename, int position, int size, boolean shareFlag) {
        access(filename, position, size, shareFlag);
    }

    private void access(String filename, int position, int size, boolean shareFlag){

        try{
            RandomAccessFile raFile = new RandomAccessFile(filename, "rw");
            FileChannel channel = raFile.getChannel();

            // Acquire Exclusive Lock
            System.out.println("Acquire Lock.");
            FileLock lock = channel.lock(position, size, shareFlag);
            System.out.println("Lock: " + lock);

            ByteBuffer buffer = ByteBuffer.allocate(size);

            channel.position(position);
            channel.read(buffer);

            System.out.println("Read " + size + " bytes from position: " +  position);
            
            javax.swing.JOptionPane.showMessageDialog(null, "Release Lock?");
            lock.release();

            channel.close();

            System.exit(0);
        }catch(FileNotFoundException ex){
            ex.printStackTrace();
        }catch(IOException ex){
            ex.printStackTrace();
        }
    }

    public static void main(String[] args){
        new FileChannelTest5(args[0],
                             Integer.parseInt(args[1]),
                             Integer.parseInt(args[2]),
                             args[3].equalsIgnoreCase("shared") ? true : false);
    }
}