我使用 JCreator 编写了这个为红色矩形设置动画的程序,我在运行动画时遇到了困难,有人有什么建议吗?
这是动画矩形的程序:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Tutorial extends JPanel implements ActionListener
{
    Timer tm = new Timer(5, this);
    int x = 0 , velX = 2;
public void paintComponent(Graphics g){
    super.paintComponent(g);
    g.setColor(Color.RED);
    g.fillRect(x, 30, 50, 30);
    tm.start();
} 
public void actionPerformed(ActionEvent e){
    x = x + velX;
    repaint();
    }
 }