JButton的默认大小不能在GridBagLayout中更改

Question

JButtons had the default size and I can't change it. I was try with setSize and it don't do anything. When I click on some of JButtons picture will be set and the JButtons will get size of the picture. I want to set size of JButton to be the same like the size of JButton when I click on it(JButton with picture)

    btn=new JButton[9];
    j=0;

    for (i = 0; i <btn.length; i++) {
        btn[i] = new JButton("");
        btn[i].addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                if(j%2==0){
                    ((JButton) e.getSource()).setIcon(new ImageIcon("resources/X.png"));
                }else{
                    ((JButton) e.getSource()).setIcon(new ImageIcon("resources/O.png"));
                }
                ((JButton) e.getSource()).setEnabled(false);
                j++;
            }
        });

    }

GridBagConstraints gbc=new GridBagConstraints();

gbc.gridx=0;
gbc.gridy=0;
p2.add(btn[0],gbc);

gbc.gridx=1;
gbc.gridy=0;
p2.add(btn[1],gbc);

gbc.gridx=2;
gbc.gridy=0;
p2.add(btn[2],gbc);

 .........

Answer 1

Probably the simplest and most reliable solution is to use a blank image which is the same size as the others as the initial image for the button

Very few layout managers allow you to directly suggest the size of a given component, in fact, the intention is to allow the component to tell the layout manager what it wants and then let the layout manager figure out if it can accomidate it.

For example...

public class TestPane extends JPanel {

    public TestPane() {
        setLayout(new GridBagLayout());
        BufferedImage img = new BufferedImage(32, 32, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = img.createGraphics();
        g2d.setBackground(new Color(255, 255, 255, 0));
        g2d.clearRect(0, 0, 32, 32);
        g2d.dispose();
        GridBagConstraints gbc = new GridBagConstraints();
        for (int row = 0; row < 3; row++) {
            gbc.gridy = row;
            for (int col = 0; col < 3; col++) {
                gbc.gridx = col;
                add(new JButton(new ImageIcon(img)), gbc);
            }
        }
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(200, 200);
    }

}

In this example I've created my own blank image, you could do the same, but it's just as easy to load blank image, the concept is the same