Prompt user to save change before abnormally closing the application

Question

Hi,
I've some trouble prompting user to save change before abnormally closing the application (logging off, shutdownding machine...). I tried to use Runtime.getRuntime().addShutdownHook() and it doesn't seem to work. Here's part of my code. Help please!!!
program print out "1" and stays in a "dead-lock" mode...
private void shutdown() {
boolean saveConfig = true;
if (saveConfig) {
System.out.println("1 ");
int answer = JOptionPane.showConfirmDialog(null,
"Configuration has been changed. Do you want to save
configuration before exit?",
"Save Config"
JOptionPane.
YES_NO_CANCEL_OPTION);
JOptionPane.showMessageDialog(this, "Can't connect to unit. Error in Heal unit!", "Error", JOptionPane.INFORMATION_MESSAGE);
System.out.println("2 ");
if (answer == 0) {
savefileButton_actionPerformed();
jMenuFileExit_actionPerformed();
else if (answer == 1) {
jMenuFileExit_actionPerformed();
else {
return;
else {
int answer = JOptionPane.showConfirmDialog(itself,
"Are you sure you want to exit? ",
"Exit",
JOptionPane.YES_NO_OPTION);
if (answer == 0) {
jMenuFileExit_actionPerformed();
else {
return;
private class MyShutdownHook extends Thread {
public void run() {
shutdown();
// add shutdown hook
MyShutdownHook shutdownHook = new MyShutdownHook();
Runtime.getRuntime().addShutdownHook(shutdownHook);

Answer 1

doesn't much matter. shutdown hooks are not guaranteed to run or be able to finish.