java repaint()无效？

初学java，绘图这里很搞不懂

package picture;import javax.swing.*; import java.awt.*;/*** Created by Smith on 2016/10/19.*/ public class Study extends JPanel{ public int x = 1; public int y = 1;public static void main(String [] args) { new Study().init(); }public void init() { JFrame jf = new JFrame("图片"); JPanel jp = new JPanel(); jf.add(jp); jf.setSize(600,600); jf.setVisible(true); Graphics g = jp.getGraphics(); for(int i = 1;i<=500;i++) { paint(g); x++; y<爱尬聊_百科词条>++; } System.out.println(g);}public void paint(Graphics g) { g.setColor(Color.blue); g.drawString("hello",x,y); repaint(); }}

生成的效果图就是如上，我实际是想要hello进行移动，但repaint()放在这里为什么没有效果