Question

does anyone know how to refresh my JFrame so I can display my new JButton ?

private void displayGrid()
{
   Case arrayGrid [][] = Grid.returnArray();

   for(int i = 0; i < Settings.returnYGrid(); i++)
    {
        for(int j = 0; j < Settings.returnXGrid(); j++)
        {
             Case caase = arrayGrid [i][j];
             panel.add(caase.getButton());
        }
}

Here is the method that I use when I create my JFrame. Then, I want to refresh my JFrame with the same method because some Case in my arrayGrid have changed and nothing is happening at all…

I tried to set revalidate(), repaint() and nothing either.

Answer 1

Try adding a call to revalidate and repaint at the end of the method…

private void displayGrid()
{
   Case arrayGrid [][] = Grid.returnArray();

   for(int i = 0; i < Settings.returnYGrid(); i++)
    {
        for(int j = 0; j < Settings.returnXGrid(); j++)
        {
             Case caase = arrayGrid [i][j];
             panel.add(caase.getButton());
        }
    }
    panel.revalidate();
    panel.repaint();
}

Updated with working example

public class TestFrame02 {

    public static void main(String[] args) {
        new TestFrame02();
    }

    public TestFrame02() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                final JPanel panel = new JPanel(new GridLayout(0, 4));
                JButton update = new JButton("Update");
                update.addActionListener(new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        for (int index = 0; index < 20; index++) {
                            panel.add(new JLabel(Integer.toString(index)));
                        }
                        panel.revalidate();
                        panel.repaint();
                    }
                });

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(panel);
                frame.add(update, BorderLayout.SOUTH);
                frame.setSize(100, 100);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }

        });
    }

}