I have a Graphics object of JPanel and that is working fine:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JPanel;
public class GraphicsTest extends JPanel
{
    private Graphics2D g2d;
    private String state;
    private int x, y;
    @Override
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        g2d = (Graphics2D) g;
        g2d.setClip(0, 0, getWidth(), getHeight());
        g2d.setColor(Color.BLACK);
        g2d.drawString("STATE: " + state, 5, 15);
        g2d.drawString("Mouse Position: " + x + ", " + y, 5, 30);
        g2d.setColor(Color.red);
        Rectangle2D r2d = new Rectangle2D.Double(x,y,10,10);
        g2d.draw(r2d);
        Test t = new Test();
        super.add(t);
        repaint();
    }
    public void setState(String state) { this.state = state; }
    public String getState() { return state; }
    public void setX(int x) { this.x = x; }
    public void setY(int y) { this.y = y; }
}
I was experimenting with a new Graphics component and when I instantiate a new Test and add it in GraphicsTest nothing happens. What is it that I am doing wrong?
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JComponent;
public class Test extends JComponent
{
    private Graphics2D g2d;
    private String state;
    private int x, y;
    @Override
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        g2d = (Graphics2D) g.create();
        g2d.setColor(Color.GREEN);
        g2d.fill(new Rectangle2D.Double(60, 60,
                10, 10));
        repaint();
    }
    public void setState(String state) { this.state = state; }
    public String getState() { return state; }
    public void setX(int x) { this.x = x; }
    public void setY(int y) { this.y = y; }
}
Thanks!