Klasa wewnętrzna / klasa anonimowa

Kody źródłowe z odcinka

package pl.am.swing.zdarzenia2;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;

public class MyFrame extends JFrame {

    private JPanel panel;

    public MyFrame() {
        setTitle("Zdarzenia");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(600, 400);

        panel = new JPanel();


        JButton button = new JButton("Zmień kolor tła");
        button.addActionListener(this::changeColour);
        panel.add(button);

        add(panel);
    }

    private void changeColour(ActionEvent e) {
        System.out.println("zostalem klikniety");
        Random random = new Random();
        int r = random.nextInt(256);
        int g = random.nextInt(256);
        int b = random.nextInt(256);
        panel.setBackground(new Color(r, g, b));
    }

    public static void main(String[] args) {
        MyFrame myFrame = new MyFrame();
        myFrame.setVisible(true);
    }
}