Question

Hi I have an Standalone application in which when an user logs in a abc.lck file gets created when the application is closed it gets deleted.I have used addshutdownhook() to delete the file when power supply is interrupted that is switching off the power supply when my application is running.My problem is the file is not getting deleted when I manually shutdown the system i.e by start–>shutdown and I should prompt the user with a message to save the changes using cofirm dailog box like in MS Word.Can some one help me
Thanking u
Chaithu

Answer 1

Use deleteOnExit method instead of adding shutdownhook. However, take a look at this sample,

class Shutdown {

  private Thread thread = null; 
  protected boolean flag=false;
  public Shutdown() {
     thread = new Thread("Sample thread") {
     public void run() {
        while (!flag) {
           System.out.println("Sample thread");
          try {
              Thread.currentThread().sleep(1000);
              } catch (InterruptedException ie) {
               break;
              }
        }
        System.out.println("[Sample thread] Stopped");
     }
   };
  thread.start();
  }
public void stopThread() {
    flag=true;
 }
}

class ShutdownThread extends Thread {
    private Shutdown shutdown = null;
    public ShutdownThread(Shutdown shutdown) {
      super();
      this.shutdown = shutdown;
    }
    public void run() {
         System.out.println("Shutdown thread");
         shutdown.stopThread();
         System.out.println("Shutdown completed");
    }
}

public class Main {
  public static void main(String [] args) {
   Shutdown shutdown = new Shutdown();
   try {
     Runtime.getRuntime().addShutdownHook(new ShutdownThread(shutdown));
     System.out.println("[Main thread] Shutdown hook added");
    } catch (Throwable t) {
      System.out.println("[Main thread] Could not add Shutdown hook");
    }

    try {
       Thread.currentThread().sleep(10000);
    } catch (InterruptedException ie) {}
    System.exit(0);
   }
}