使用Timer在JLabel中更改ImageIcon

Question

I have two classes: logic and the JFrame . In frame I have a JLabel and a JButton , and I would like to:

When this button is clicked, the ImageIcon in the label changes after a determined time using a Swing Timer , like if it is flashing. To do it I loaded two images with different brightness ( img1b and img1 ). I tried to make the timer change the image twice with different delays, but I was unsuccessful. I also put a listener in the button and implemented the actionPerformed as below:

public void actionPerformed(ActionEvent e) {
    if(e.getSource().equals(btnImg1)) {
        logic.piscaImagen(img1, lblImg1);
        logic.piscaImagen(img1b, lblImg1);

In logic class:

public void piscaImagen(ImageIcon img, JLabel lbl) {

        Timer timer = new Timer(1250, null);
        timer.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent evt){
                if(lbl.getIcon() != img){
                    lbl.setIcon(img);
            }
        }
        });
        timer.setRepeats(false);
        timer.start();
}

But when I run it nothing changes in the logic.piscaImagen . Any tips?

Answer 1

logic.piscaImagen(img1, lblImg1);
logic.piscaImagen(img1b, lblImg1);

It looks to me like you are starting two Timers. So the first Timer fires and it changes the image, then the second timer fires and it restores the image so basically you only see the first image.

All you need is one Timer. Each time the Timer fires you change the image. So the basic code in your Timer would be:

if (lbl.getIcon() == img1)
    lbl.setIcon(img1b);
else
    lbl.setIcon(img1);

Or for a more flexible solution you can use the Animated Icon .

The Animated Icon will allow you to specify a List of Icons to display. Then when the Timer fires the next Icon in the List is displayed. You can set the Animated Icon for continuous display or you can control the number of cycles.

Answer 2

EDIT : answer inaccurate, repaint() not necessary - see comments.

---

You're missing the repaint() call that tells the program it needs to update the display.

@Override
public void actionPerformed(ActionEvent evt) {
    if(lbl.getIcon() != img){ 
        lbl.setIcon(img);
        lbl.repaint();
    }
}

(your if statement was also missing a closing brace, unsure what impact that would have / if it was a typo)