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);
        }
    }
}