I’m writing an Eclipse RCP and I want to ask the user whether to

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Asked: May 26, 20262026-05-26T01:39:25+00:00 2026-05-26T01:39:25+00:00

I’m writing an Eclipse RCP and I want to ask the user whether to

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I’m writing an Eclipse RCP and I want to ask the user whether to backup the database when the application is closed. Doing it from the File>Exit menu was easy as I defined a command exit:

public class ExitCommand extends AbstractHandler implements IHandler {

@Override
public Object execute(ExecutionEvent event) throws ExecutionException {
    final IWorkbench workbench = PlatformUI.getWorkbench();
    if (workbench == null)
        return null;

    // Ask whether the user wants to back up the information
    Shell shell = new Shell(workbench.getDisplay());
    MessageBox messageBox = new MessageBox(shell, SWT.ICON_QUESTION
            | SWT.YES | SWT.NO);
    messageBox.setMessage("You are leaving CatSysPD. Do you want to make a backup of the DataBase? (recommended)");
    messageBox.setText("On Exit Backup");
    int response = messageBox.open();
    if (response == SWT.YES){
        new BackupDataBaseAction(shell);
    }

    final Display display = workbench.getDisplay();
    display.syncExec(new Runnable() {
        public void run() {
            if (!display.isDisposed())
                workbench.close();
        }
    });
    return null;
}}

I then linked this to a menu entry called Exit and this work right. However the user could close the application also by pressing the “close window” button. Is there any way of catching this event?

I found a suggestion in a previous topic (see here) using a shutdownHook. However the thread that I want execute has to open a dialog and, as I understand, this cannot be done by an external thread.

Thank you!

Edit
I add here the code for the shutdownHook I’m using. In the Application class:
public class Application implements IApplication {

final double NIDAQmxPortingVersionDependency = 1.001;

public final static String PLUGIN_ID = "CatsysPD";
private static Logger logger = Logger.getLogger(Application.class
        .toString());

/*
 * (non-Javadoc)
 * 
 * @see org.eclipse.equinox.app.IApplication#start(org.eclipse.equinox.app.
 * IApplicationContext)
 */
public Object start(IApplicationContext context) {
    logger.info("Starting the application");
    Display display = PlatformUI.createDisplay();
    systemCheck(display);
    initializeApplication(display);
    try {
        int returnCode = PlatformUI.createAndRunWorkbench(display,
                new ApplicationWorkbenchAdvisor());
        if (returnCode == PlatformUI.RETURN_RESTART) {
            return IApplication.EXIT_RESTART;
        }
        BackupOnExitHook backupOnExitHook = new BackupOnExitHook(PlatformUI.getWorkbench().getDisplay());
        Runtime.getRuntime().addShutdownHook(backupOnExitHook);
        return IApplication.EXIT_OK;
    } finally {
        display.dispose();
    }
}

private void systemCheck(Display display) {...}

public void stop() {...}

public void initializeApplication(Display display) {...}

private class BackupOnExitHook extends Thread {

    private Display display;

    public BackupOnExitHook(Display display){
        this.display = display;
    }

    @Override
    public void run(){
        display.syncExec(new Runnable(){

            @Override
            public void run() {
                MessageBox messageBox = new MessageBox(new Shell(display), SWT.ICON_QUESTION
                        | SWT.YES | SWT.NO);
                messageBox.setMessage("You are leaving CatSysPD. Do you want to make a backup of the DataBase? (recommended)");
                messageBox.setText("On Exit Backup");
                int response = messageBox.open();
                if (response == SWT.YES){
                    new BackupDataBaseAction(new Shell(display));
                }
            }});


    }

}
}

The error I get when I try to run it is:

Exception in thread "Thread-5" org.eclipse.swt.SWTException: Device is disposed
at org.eclipse.swt.SWT.error(SWT.java:4083)
at org.eclipse.swt.SWT.error(SWT.java:3998)
at org.eclipse.swt.SWT.error(SWT.java:3969)
at org.eclipse.swt.widgets.Display.error(Display.java:1249)
at org.eclipse.swt.widgets.Display.syncExec(Display.java:4581)
at dk.catsys.pd.Application$BackupOnExitHook.run(Application.java:128)

Thanks again.