How to change image with the click of a button in java

Question

If already an image is display, by clicking a button how can i change it to another one?

Say I have two image buffered.

bi = ImageIO.read(new File("1.jpg");
bi2 = ImageIO.read(new File("2.jpg"));

and to display the bi I am using

public void paint(Graphics g){
    super.paintComponent(g);

    Dimension dim = Toolkit.getDefaultToolkit().getScreenSize(); 
    int w = ((int) dim.getWidth() / 2) - (bi.getWidth() / 2);
    int h = ((int) dim.getHeight() / 2) - (bi.getHeight() / 2);

    g.drawImage(bi, w, h, null);
}

I am tried to do this.

JButton b = new JButton("Change Image");
b.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent ae){
        bi = bi2;
        paint(null);
    }
});

this set bi to a new image and paint() method called, but the image viewer itself doesnt appear at all now.

continuation of how to set JFrame background transparent but JPanel or JLabel Background opaque?

Why don't you just use `setImageIcon(imageIcon)` method of button? — Harry Joy, Aug 23 '12 at 04:15
The easiest way is to use them as alternate icons on an undecorated button, as shown in [this answer](http://stackoverflow.com/a/7360696/418556). — Andrew Thompson, Aug 23 '12 at 04:15
@HarryJoy I guess it would depend on if the OP is painting Icons on a button or not. They could be painting to the container instead? You point is, however, valid (+1 to you) - you could also use a `JLabel` instead — MadProgrammer, Aug 23 '12 at 04:20
For better help sooner, post an [SSCCE](http://sscce.org/). Note that `public void paint(Graphics g){ super.paintComponent(g);` is almost certainly wrong. Will know more when I see an SSCCE. — Andrew Thompson, Aug 23 '12 at 05:20
@AndrewThompson +1 for the pick up on `super.paintComponent` missed that — MadProgrammer, Aug 23 '12 at 07:40

score 3 · Answer 1 · answered Aug 23 '12 at 04:14

You need to request a repaint.

JButton b = new JButton("Change Image");
b.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent ae){
        bi = bi2;
        //invalidate();
        repaint();
    }
});

It may also be necessary to call invalidate first to allow the container to be marked for repainting by the repaint manager

If you know the area to be painted (ie the old area and the new area) you could call paintImmediately instead

So something like this could also work...

int w = ((int) dim.getWidth() / 2) - (bi.getWidth() / 2);
int h = ((int) dim.getHeight() / 2) - (bi.getHeight() / 2);
Rectangle oldArea = new Rectangle(w, h, bi.getWidth(), bi.getHeight());

bi = bi2;
w = ((int) dim.getWidth() / 2) - (bi.getWidth() / 2);
h = ((int) dim.getHeight() / 2) - (bi.getHeight() / 2);
Rectangle newArea = new Rectangle(w, h, bi.getWidth(), bi.getHeight());

Area area = new Area();
area.add(oldArea);
area.add(newArea);

Rectangle updateArea = area.getBounds();
paintImmediately(updateArea);

@sabbibJAVA not use CardLayout – mKorbel Aug 23 '12 at 07:36 — mKorbel, Aug 23 '12 at 07:36

How to change image with the click of a button in java

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