CODEWITHSUNDEEP
javaswinguser-interfacejpanelrepaint
Ann
Ann

Reputation: 11

revalidate() and repaint() not updating my JPanel

I'm trying to make a program in which a displayed JTabel changes according to the user's choice of files. They input this by clicking a button that calls on some method(), that returns a new JTable. But I cannot get the table in the GUI to update. 

public class program extends JFrame{

public JPanel panel;
public JTable table;

  public program{
    this.panel = new JPanel();
    panel.setLayout(new FlowLayout());

    JTable table = new JTable();
    panel.add(table);

    JButton button = new JButton();
    button.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
            JFileChooser chooser = new JFileChooser();
            if(browser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION){ 
            table = method(); //some method that changes the values of the table 
            panel.revalidate();
            panel.repaint();
            }
        };
    });
    panel.add(button);

    setContentPane(panel);
    setVisible(true);
  }

private static JTable method(){ ... }

public static void main(String[] args){
  program something = new program();
}

}

I'm not entirely sure on the differences between validate(), revalidate(), and repaint() despite reading a lot about them. I've also tried table.revalidate() ect. instead, but that's no good either.

EDIT: Thanks for the help, it's all sorted now :) I rewrote my ActionListener as "instructed" by resueman:

   JButton button = new JButton();
   button.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent e){
        JFileChooser chooser = new JFileChooser();
        if(browser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION){  
        panel.remove(table);
        table = method();
        panel.add(table);
        panel.revalidate();
        panel.repaint();
        }
    };
});

I've hesitated to do this since FlowLayout would place it somewhere I didn't want it. But with additional JPanels inside the primary one, it can be controlled.

Thanks for the comments, you all just saved my day!

Upvotes: 1

Views: 1374

Answers (1)

Jan
Jan

Reputation: 13858

If you could redesign to change the tables contents you wouldn't need to worry about manually repainting.

Try to modify your code to

 table.setModel (method());

And model () returning a TableModel instead of a JTable.

You don't see any changes because the old JTable is still added to your panel. You'd have to remove old / add new if you insist of keeping your method the way it is.

Good Luck.

Upvotes: 2

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