图形用户界面不可见错误

Question

My Main code

import javax.swing.JFrame;

public class PotLuck {

private static JFrame frame;

public static void main(String[] args) {
    frame = new JFrame("POT LUCK V1.0");
    PotLuckPanel panel3 = new PotLuckPanel();
    frame.add(panel3);
    frame.setSize(300,300);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   
}
}

My PotLuckPanel class

import java.awt.BorderLayout;

public class PotLuckPanel extends JPanel  {

private JLabel statusBar;
private int guessCounter=0;

public PotLuckPanel(){

JPanel panel = new JPanel(new BorderLayout());  
JPanel panel2 = new JPanel();

panel2.setLayout(new GridLayout(5,5));
for(int i=0 ; i< 25 ; i++){
    JButton buttoni = new JButton();
    panel2.add(buttoni);
}

statusBar = new JLabel("Number of guess:"+ guessCounter);
panel.add(statusBar, BorderLayout.NORTH);
panel.add(panel2, BorderLayout.SOUTH);
}
 }

Buttons are not visible, panels either. Only frame is appearing. When I compile there is no error. What is my error? How can I fix it?

Answer 1

Try to set layout to frame as

frame.setLayout(new FlowLayout());

Or any other layout in main method. And it will be visible.

Answer 2

The problem is that your PotLuckPanel is a JPanel , but you never add any components to it.

There is no need for you to create the "panel" variable. You just set the layout of your class and than add the components directly to it:

//JPanel panel = new JPanel(new BorderLayout());  
setLayout( new BorderLayout() ):

...

//panel.add(statusBar, BorderLayout.NORTH);
//panel.add(panel2, BorderLayout.SOUTH);
add(statusBar, BorderLayout.NORTH);
add(panel2, BorderLayout.SOUTH);