import java.awt.*;

public class TestPaint {
    public static void main(String[] args) {
        new MyPaint().loadFrame();
    }
}
class MyPaint extends Frame{

    public void loadFrame(){
        setBounds(200,200,600,400);
        setVisible(true);
    }
    @Override
    public void paint(Graphics g) {

        g.setColor(Color.red);
        g.drawOval(100,100,100,100);

        g.setColor(Color.GREEN);
        g.fillRect(150,150,200,200);

        //画笔用完，需要将其还原到最初的颜色
    }
}