Use GridBagConstraints to update layout

Question

I use GridBagConstraints to update my layout, when a button have been clicked, some input fields will appear.

private class EventListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            input_panel.removeAll();
               String str = e.getActionCommand();
               System.out.print(str);

               JLabel jl = new JLabel("Label ");
            // Create constraints
               GridBagConstraints textFieldConstraints = new GridBagConstraints();
               GridBagConstraints labelConstraints = new GridBagConstraints();

               labelConstraints.gridx = 0;
               labelConstraints.gridy = 0;

               input_panel.add(jl,textFieldConstraints);
        }
    }

This function successfully runs, however, there is a strange problem, when I click the button, it do update, but not show immediately, I must need to resize the window to see it. What happens?

score 4 · Accepted Answer · edited Dec 09 '12 at 14:30

4

input_panel.add(jl,textFieldConstraints);
input_panel.revalidate(); //try to add this
input_panel.repaint(); // and this

edited Dec 09 '12 at 14:30

Hovercraft Full Of Eels

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answered Dec 09 '12 at 14:28

Nikolay Kuznetsov

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Or better, `revalidate()` followed by `repaint()` – Hovercraft Full Of Eels Dec 09 '12 at 14:29
Edit made. The repaint will be necessary at times, especially if components are removed. @PandaYang: understand that `revalidate()` asks the container layout managers to re-layout their components recursively, and the `repaint()` allows the painting methods to clean up any dirty screen portions. – Hovercraft Full Of Eels Dec 09 '12 at 14:30
@HovercraftFullOfEels, thanks! I was always wondering about difference of `validate`, `revalidate`, `repaint`. – Nikolay Kuznetsov Dec 09 '12 at 14:32
@PandaYang: if Nikolay's advice helped you, please "accept" his answer. – Hovercraft Full Of Eels Dec 09 '12 at 14:34
@PandaYang, please, don't forget ;) – Nikolay Kuznetsov Dec 09 '12 at 15:35
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@NikolayKuznetsov : Hopefully this thread, [Difference between validate(), revalidate() and invalidate()](http://stackoverflow.com/q/9510125/1057230), might be of some interest to you :-) – nIcE cOw Dec 09 '12 at 15:51

Use GridBagConstraints to update layout

1 Answers1