import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.Ellipse2D;
import javax.swing.*;
public class testpaint extends JFrame{
public static void main(String[] args) {
testpaint t=new testpaint();
t.setLocation(100, 100);
t.setSize(500, 400);
t.getContentPane().setBackground(Color.green);
t.setVisible(true);
}
public void paint(Graphics g){
super.paint(g);
Graphics2D g2 = (Graphics2D)g;
Ellipse2D e = new Ellipse2D.Double(10,50,70,70);
//加上下面这句就能变的圆滑了
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setPaint(Color.RED);
g2.draw(e);
//g2.fill(e);
}
}
