How could I add a simple delay in a Java Swing application?
Solution 1:
Here's an example using a javax.swing.Timer
public class TestBlinkingText {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new BlinkPane());
frame.setSize(200, 200);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
protected static class BlinkPane extends JLabel {
private JLabel label;
private boolean state;
public BlinkPane() {
label = new JLabel("Look at me!");
setLayout(new GridBagLayout());
add(label);
Timer timer = new Timer(500, new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
state = !state;
if (state) {
label.setForeground(Color.RED);
} else {
label.setForeground(Color.BLACK);
}
repaint();
}
});
timer.setRepeats(true);
timer.setCoalesce(true);
timer.setInitialDelay(0);
timer.start();
}
}
}
Solution 2:
Good thing you removed the Thread.sleep
as that would make your UI unresponsive for those 2 seconds.
What you can do is start a Timer
which only runs once:
int delay = 2000;
Timer timer = new Timer( delay, new ActionListener(){
@Override
public void actionPerformed( ActionEvent e ){
jLabel12.setForeground( Color.red );
}
} );
timer.setRepeats( false );
timer.start();
Note that the Timer
is a javax.swing.Timer
, which assures that the actionPerformed
method of the ActionListener
is called on the Event Dispatch Thread, respecting the Swing threading rules.
This is also possible with a SwingWorker
, but I would stick to the Timer
for this. In case you want to use the SwingWorker
, you can simply use Thread.sleep
in the doInBackground()
method, and update the JLabel
in the done()
method.
Something along the lines of
class Delay extends SwingWorker<Void, Object> {
@Override
public void doInBackground() {
Thread.sleep( 2000 );
}
@Override
protected void done() {
jLabel12.setForeground( Color.red );
}
}