Progress Bar value is not updating

Question

Here runQuery() function executes a query on 4 databases. I want tprogrssBar value should be updated to 50 on screen before it starts running runQuery() function. But screen gets updated after runQuery() is executed.

public void actionPerformed(ActionEvent e) {
        String s = e.getActionCommand();
        progressBar.setValue(50);
        runQuery();
    }