How to use a JProgressBar in a different Thread?

Question

I'm using POI in a function to fill the content of my excel document (it takes 10 seconds) and when i call my function I want to use a JProgressBar to see the progress, but the button and the program is block, i need to to make in other thread? and how can I do it? an example of my code:

btnEjecutar.addMouseListener(new MouseAdapter() {
        @Override
        public void mouseClicked(MouseEvent arg0) {
        //the function
        generarDocumento(nombre);
            }

Answer 1

Event listeners are executed in the UI thread. If an event listener takes a long time, the UI will stop working/lock up/block/hang.

My guess is that the method generarDocumento() takes a long time. If you want the UI to continue working, you must run it in a worker thread. The Java documentation contains several examples how to do that: https://docs.oracle.com/javase/tutorial/uiswing/concurrency/worker.html

The last example in the tutorial contains demo code how to update a progress bar: https://docs.oracle.com/javase/tutorial/displayCode.html?code=https://docs.oracle.com/javase/tutorial/uiswing/examples/components/ProgressBarDemoProject/src/components/ProgressBarDemo.java

Note: The linked content is copyrighted; therefore I can't copy it here.

Answer 2

Try to use an invokeLater, like the example bellow:

SwingUtilities.invokeLater(new Runnable() {
    public void run() {
        generarDocumento(nombre);
    });