JFrame + JPanel

JJFrame.java

package lesson5_8;


import javax.swing.*;
import java.awt.*;

public class JJFrame extends JPanel{

    public static void main(String[] args) {

        new JJFrame();
    }

    public JJFrame() {

        JFrame f = new JFrame("Day5_8");
        f.setMinimumSize(new Dimension(800, 600));
        f.setLocation(300, 100);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(this);
        f.pack();

        f.setVisible(true);
    }

    @Override
    protected void paintComponent(Graphics g) {

        super.paintComponent(g);
        this.setBackground(Color.CYAN);
    }
}