Question

I have this “main” panel (let’s call it AAA) with BorderLayout, and two panels (BBB and CCC) in it:

public class AAA extends JPanel {
    BBB pnlNorth = new BBB();
    CCC pnlCenter = new CCC();
    public AAA(){
        setLayout(new BorderLayout());
        add(pnlNorth,BorderLayout.NORTH);
        add(pnlCenter,BorderLayout.CENTER);        
    }
}

Panel CCC is currently empty, with GridLayout.

My panel BBB looks like this:

public class BBB extends JPanel {
    public BBB (){
        JLabel labNum = new JLabel("Number of items: ");
        JTextField txtNum = new JTextField();
        JButton cmdOK = new JButton("OK");
        txtNum.setColumns(5);
        cmdOK.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                /* ???????????? */
            }
        });
        add(labNum);
        add(txtNum);
        add(cmdOK);        
    }
}

When a user enters a number in txtNum and presses “OK”, panel CCC should be populated with appropriate number of rows for data input. Each row should contain two text fields, two drop-down lists and a checkbox. It would be nice if all the items would be in a JScrollPane, if the user enters some large number.

My question: How should I implement the action listener in BBB? I have no idea what number will be typed in by the user. Therefore, I don’t know the precise number of rows in CCC‘s GridLayout (I just know it should have 5 columns). Can I modify its layout from the listener in BBB? And how can I add components to the panel CCC from the listener in the panel BBB?

Of course, if you have better solution (without two separate panels), let me know 🙂

Answer 1

I managed to do this. I simply passed the Center panel as a parameter in the North panel’s constructor. It works perfectly. Thank you all for the answers 🙂