Can't create multiple instances of a class in Java

I'm trying to create multiple characters(squares) on the screen that move around randomly. I have already created a CharMove class that creates a square, and moves it around randomly on the screen. However, I tried creating multiple instances of this class in a seperate java file and only 1 instance was created. What is wrong?

CharMove Class:

public class CharMove extends JPanel {
    public static int x = 250;
    public static int y = 250;

    public void paint(Graphics g) {
        Graphics pane = (Graphics2D) g;
        pane.setColor(Color.blue);
        pane.fillRect(x, y, 10, 10); 

    }

    public static void movement(int x, int y, JFrame frame) { 
        CharMove.x = x; 
                CharMove.y = y;
        while (true) {
            try {
                TimeUnit.SECONDS.sleep(1);
                CharMove.x = Getx(CharMove.x,frame); 
                CharMove.y = Gety(CharMove.y,frame);
                frame.repaint();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static int Getx(int a, JFrame frame) { 
        Random rn = new Random();
        int xnum = rn.nextInt(10)-5; 
        a += xnum; 
        System.out.println("x:" + a); 
        return a;
    } 
    public static int Gety(int b, JFrame frame){ 
        Random rn = new Random();
        int ynum = rn.nextInt(10)-5; 
        b += ynum; 
        System.out.println("y:" + b); 
        return b;
    } 
}

World Class

public static void main(String[] args) {
    JFrame game = new JFrame();
    game.setTitle("Matrix");
    game.setSize(500, 500);;
    game.getContentPane().setBackground(Color.white);
    game.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    game.setVisible(true);  
    CharMove char1 = new CharMove(); 
    CharMove char2 = new CharMove();
    game.add(char1);   
    game.add(char2);
    char1.movement(100,100,game); 
    char2.movement(250,250,game);
}