JPanel没有出现在另一个JPanel中

Question

class ABC extends JFrame {
    public JPanel createGUI()
    {
        JPanel outerPanel = new JPanel();
        outerPanel.setLayout(null);

        JLabel top = new JLabel();
        top.setBounds(40,40,400,30);
        top.setText("Hello World");
        outerPanel.add(top);

        int l = getLength();
        JPanel innerPanel = new JPanel();
        if(l==0)
        {
            innerPanel.setLayout(null);
            JLabel empty = new JLabel("No Data Found");
            empty.setBounds(80,150,300,30);
            innerPanel.add(empty);
        }
        else
        {
            innerPanel.setLayout(new GridLayout(l,4,5,5)); 
            for(int i=0;i<l;i++)
            {
                innerPanel.add(new JLabel("Text1");
                innerPanel.add(new JLabel("Text2");

                JButton b1 = new JButton("Button1");
                innerPanel.add(b1);
                JButton b2 = new JButton("Button2");
                innerPanel.add(b2);
            }          
         }
         outerPanel.add(innerPanel);
         return outerPanel;
    }
}

In the above code the innerPanel does not show up and neither any error occurs.Any idea how to show up the innerPanel which is inside an outerPanel.I tried using getContentPane().add(innerPanel) but it didn't work.

Answer 1

Try changing

outerPanel.setLayout(null);

to

outerPanel.setLayout(new FlowLayout());

or remove the setLayout call entirely.