ActionListener and ActionPerformed

import javax.swing.*;
import java.awt.event.*;
public class ChangeButtonLabel{
  JButton button;
  JDialog dispay;
  MainMenu myDispay;
  public static void main(String[] args){
    ChangeButtonLabel cl = new ChangeButtonLabel();
  }
  public ChangeButtonLabel(){
    JFrame frame = new JFrame("Change JButton Lebel");
    dispay=new JDialog();
    button = new JButton("Click Me");
    myDispay=new MainMenu();  ///MainMenu class file should present in current folder as well as this class must extend from JPanel
    button.addActionListener(new MyAction());
    frame.add(button);
    dispay.add(myDispay);
    frame.setSize(400, 400);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
  public class MyAction implements ActionListener{
    public void actionPerformed(ActionEvent e)
   {
               dispay.setSize(300, 300);
               dispay.setVisible(true);
   }
  }
}