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++;         }         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