import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.Color;
import java.awt.GradientPaint;

public class PaintTest2 extends JPanel{

  public static void main(String[] args){
    JFrame frame = new JFrame();

    PaintTest2 app = new PaintTest2();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("ƒ^ƒCƒgƒ‹");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g){
    Graphics2D g2 = (Graphics2D)g;

    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
                        RenderingHints.VALUE_ANTIALIAS_ON);

    GradientPaint gradient = new GradientPaint(
        50.0f, 50.0f, Color.ORANGE, 
        190.0f, 110.0f, Color.YELLOW
    );
    g2.setPaint(gradient);

    g2.fill(new Rectangle2D.Double(20, 20, 200, 130));

/*
    g2.setPaint(Color.black);
    g2.draw(new Ellipse2D.Double(45, 45, 10, 10));
    g2.draw(new Ellipse2D.Double(185, 105, 10, 10));
*/
  }
}