java thread.sleep puts swing ui to sleep too

Question

I im creating a simple testing app that runs a check every hour on the selected directory/s using thread.sleep() through JFileChooser. But when i select the directory and the method runs the ui panel goes grey and the swing bits disappear. The thread seems to be putting the ui to sleep as well as the method its calling.

if (option == JFileChooser.APPROVE_OPTION) {
    selectedDirectory = chooser.getSelectedFiles();
    try {
        while (true) {
            runCheck(selectedDirectory);
            Thread.sleep(1000*5);//1000 is 1 second
        }
    } catch (InterruptedException e1) {
        Thread.currentThread().interrupt();
        e1.printStackTrace();
    }               
} 

Im looking for a way around this issue so that i can print the results of the checks being run in the ui .setText(result)

Answer 1

You are correct about the code putting the UI to sleep. Since sleep is called on the Event Dispatch Thread (the thread responsible for running the gui) the UI stops processing events and 'goes to sleep'.

I think what you want is a javax.swing.Timer.

Timer t = new Timer(1000 * 5, new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        // do your reoccuring task
    }
});

This will cause your reoccurring task to be performed off of the EDT, and thus it wont leave your ui unresponsive.

Answer 2

If the code you have posted runs on the EventDispatchThread, then there is no way Swing can redraw the GUI. You're blocking (sleeping in) the thread that's supposed to handle that!