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

class NewJFrame extends JComponent {
    public NewJFrame() {
        super();
    }

    @Override
    protected void paintComponent(Graphics brush) {
        Graphics newBrush = brush.create();
        
        if (this.isOpaque()) {
            newBrush.setColor(this.getBackground());
            newBrush.fillRect(0, 0, this.getWidth(), this.getHeight());
        }

        newBrush.setColor(this.getForeground());

    }
}

public class Formes {
    public static void main(String[] args) {
        JFrame f = new JFrame("Formes");
        f.setSize(500, 500);
        f.setLocation(100, 100);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        f.setVisible(true);
    }
}