import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;


public class cricle extends JFrame {

    int x=80,y=80;
    
    public void launch(){
        //setLocation(400, 300);
        setSize(700,800);
        setLocationRelativeTo(null);  //jframe居中显示
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);  //jframe不可改变大小
        setBackground(Color.YELLOW);
        setVisible(true);
        Thread t=new Thread(new RunTank());
        t.start();
    }
    
    //画物体        
                          public void paint(Graphics g){
            Color c=g.getColor();
            g.setColor(Color.red);
            g.fillOval(x,y, 40, 40);
            g.setColor(c);
            y+=50;
        }
        
        //物体运动
        class RunTank implements Runnable{

            public void run() {
                while(true) {
                    repaint();
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
    }
    
    
    public static void main(String[] args) {

        cricle tan= new cricle();
        tan.launch();

    }
    

}