Make the buttons members of CenterPanel
class CenterPanel{
JPanel center = new JPanel();
JButton enterButton;
JButton exitButton;
public void renderPanel(){
enterButton = new JButton("enter");
exitButton = new JButton("exit");
center.add(exitButton);
center.add(enterButton);
}
public JButton getEnterButton()
{
return enterButton;
}
public JButton getExitButton()
{
return exitButton;
}
public JComponent getGUI(){
return center;
}
}