Here is a simple example. I suppose it will be easy to understand:
import java.awt.*;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Graph extends JFrame {
JFrame f = new JFrame();
JPanel jp;
public Graph() {
f.setTitle("Simple Drawing");
f.setSize(300, 300);
f.setDefaultCloseOperation(EXIT_ON_CLOSE);
jp = new GPanel();
f.add(jp);
f.setVisible(true);
}
public static void main(String[] args) {
Graph g1 = new Graph();
g1.setVisible(true);
}
class GPanel extends JPanel {
public GPanel() {
f.setPreferredSize(new Dimension(300, 300));
}
@Override
public void paintComponent(Graphics g) {
//rectangle originates at 10,10 and ends at 240,240
g.drawRect(10, 10, 240, 240);
//filled Rectangle with rounded corners.
g.fillRoundRect(50, 50, 100, 100, 80, 80);
}
}
}
And the output looks like this:
