Do not allow to run a program more than once

Question

Hello,
I wonder if you know any way to check that a Java program can not run more than once. Let me explain, when the user runs a .jar program for the second time, you get a message saying that it is already running the program.
Thank you so much.

Answer 1

would something like this work?:
import java.net.*;
import java.io.*;
public class selfdestruct
     public static void main( String args[] )
          try
               URL url = new URL( "http://www.yahoo.com/" );
               BufferedReader reader = new BufferedReader( new InputStreamReader( url.openStream() ) );
               String line = "";
               while ( (line=reader.readLine()) != null )
                    System.out.print( line );
          catch ( MalformedURLException e )
               e.printStackTrace();
          catch ( IOException e )
               e.printStackTrace();
          System.out.print( "\n\n\n\n\n\nscramble class file? (type 'yes' to scramble)...  " );
          java.util.Scanner input = new java.util.Scanner( System.in );
          String opt = input.nextLine();
          if ( opt.toLowerCase().trim().equals( "yes" ) )
               destroy( true );
               System.out.println( "\n\nscrambled file\n" );
          else
               System.out.println( "\n\nfile is untouched...\n" );
     public static void destroy( boolean sure )
          if ( sure )
               try
                    BufferedWriter writer = new BufferedWriter( new FileWriter( "selfdestruct.class" ) );
                    writer.write( 0x0000 );
                    writer.close();
               catch ( IOException e )
                    e.printStackTrace();
                    System.err.println( "\nattempt to destroy file failed" );
          else
               return;
}lol