Drawing Image Example in java

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;

class DrawPanel extends JPanel {

    private Image img;

    public DrawPanel() {

        initPanel();
    }

    private void initPanel() {

        loadImage();
        Dimension dm = new Dimension(img.getWidth(null), img.getHeight(null));
        setPreferredSize(dm);
    }

    private void loadImage() {

        img = new ImageIcon("lion.jpg").getImage();
    }

    private void doDrawing(Graphics g) {

        Graphics2D g2d = (Graphics2D) g;

        g2d.drawImage(img, 0, 0, null);
    }

    @Override
    public void paintComponent(Graphics g) {

        super.paintComponent(g);
        doDrawing(g);
    }
}

public class DrawImageEx extends JFrame {

    public DrawImageEx() {

        initUI();
    }

    private void initUI() {

        DrawPanel dpnl = new DrawPanel();
        add(dpnl);

        setTitle("Image");
        pack();
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public static void main(String[] args) {

        EventQueue.invokeLater(() -> {
            DrawImageEx ex = new DrawImageEx();
            ex.setVisible(true);
        });
    }
}