How to lock a process in java to prevent multiple instance at the same time

prevent_multiple_instance_run

http://www.dscripts.net/2010/06/09/how-to-lock-a-process-in-java-to-prevent-multiple-instance-at-the-same-time/


//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// check if another process is running
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
package utils;
 
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
 
/**
 *
 * @author Burhan Uddin
 */
public class lock {
    private static File f;
    private static FileChannel channel;
    private static FileLock lock;
 
    public lock()
    {
        try
        {
            f = new File("process.lock");
            // Check if the lock exist
            if (f.exists()) // if exist try to delete it
                f.delete();
            // Try to get the lock
            channel = new RandomAccessFile(f, "rw").getChannel();
            lock = channel.tryLock();
            if(lock == null)
            {
                // File is lock by other application
                channel.close();
                throw new RuntimeException("Two instance cant run at a time.");
            }
            // Add shutdown hook to release lock when application shutdown
            ShutdownHook shutdownHook = new ShutdownHook();
            Runtime.getRuntime().addShutdownHook(shutdownHook);
 
        }
        catch(IOException e)
        {
               throw new RuntimeException("Could not start process.", e);
        }
    }
 
    public static void unlockFile() {
        // release and delete file lock
        try
        {
            if(lock != null)
            {
                lock.release();
                channel.close();
                f.delete();
            }
        }
        catch(IOException e)
        {
            e.printStackTrace();
        }
    }
 
    static class ShutdownHook extends Thread {
        public void run() {
            unlockFile();
        }
    }
}


//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
package msngr;
 
import utils.lock;

public class Main {
    public static void main(String[] args) {
        .....
        lock l = new lock();
        ....
    }
}

awesome