|  | Home > List of Packages > java.awt [78 examples] > Drawing [7 examples] ### e575. The Quintessential Drawing Program To draw on the screen, it is first necessary to subclass a `JComponent` and override its `paint()` method. The `paint()` method is automatically called by the windowing system whenever component's area needs to be repainted. The `paint()` method is supplied a graphics context which is used to draw shapes and images. The coordinate system of a graphics context is such that the origin is at the northwest corner and x-axis increases toward the right while the y-axis increases toward the bottom. This example defines a component that draws an oval and installs an instance of this component in a frame. See also e586 Drawing Simple Shapes.
        import java.awt.*;
        import javax.swing.*;

        public class BasicDraw {
            public static void main(String[] args) {
                new BasicDraw();
            }
            BasicDraw() {
                // Create a frame
                JFrame frame = new JFrame();

                // Add a component with a custom paint method
                frame.getContentPane().add(new MyComponent());

                // Display the frame
                int frameWidth = 300;
                int frameHeight = 300;
                frame.setSize(frameWidth, frameHeight);
                frame.setVisible(true);
            }

            class MyComponent extends JComponent {
                // This method is called whenever the contents needs to be painted
                public void paint(Graphics g) {
                    // Retrieve the graphics context; this object is used to paint shapes
                    Graphics2D g2d = (Graphics2D)g;

                    // Draw an oval that fills the window
                    int x = 0;
                    int y = 0;
                    int width = getSize().width-1;
                    int height = getSize().height-1;
                    g2d.drawOval(x, y, width, height);
                }
            }
        }