Java Adding Shapes To Existing Jframe

How do I draw a semi circle in java?

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

public class YAnswers extends JPanel{

public void paint(Graphics g){
g.setColor(Color.red);
g.fillOval(50,50,100,100);
g.setColor(Color.white);
g.fillArc(50, 50, 100, 100, 0, 180);
g.setColor(Color.black);
g.drawLine(50, 100, 150, 100);
}

public static void main(String[] args){
JFrame jf=new JFrame();
jf.setDefaultCloseOperation
(JFrame.EXIT_ON_CLOSE);
jf.setPreferredSize(new Dimension(300,500));
jf.add(new YAnswers());
jf.pack();
jf.setVisible(true);
}
}

Java: Draw Olympic Rings?

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