Removing an Image off a JFrame

Question

I have been trying to make this program display an image and then replace and then after a second it will remove the image and replace it with a different one after one second. Which image to display is controlled by a random int i. Everything works except the images stack up next to each other and aren't deleted. I have looked everywhere and still can't find anything that works for me.

public Frame() {
    this.setTitle("Fast Number");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel1 = new JPanel();

    while(true){
        System.out.println("Random Int:   "+ i);
        if(i == 1){
            ImageIcon pic = new ImageIcon("//Users//evan//Documents//workspace//Fast Number//res//ArrowUp.png");
            panel1.add(new JLabel(pic));
        } else if (i == 2){
            ImageIcon pic = new ImageIcon("//Users//evan//Documents//workspace//Fast Number//res//ArrowDown.png");
            panel1.add(new JLabel(pic));
        }else if (i == 3){
            ImageIcon pic = new ImageIcon("//Users//evan//Documents//workspace//Fast Number//res//ArrowLeft.png");
            panel1.add(new JLabel(pic));
        }else if (i == 4){
            ImageIcon pic = new ImageIcon("//Users//evan//Documents//workspace//Fast Number//res//ArrowRight.png");
            panel1.add(new JLabel(pic));
        } 

        try {
            Thread.sleep(1000);
        } catch (InterruptedException ex) {
             Thread.currentThread().interrupt();
        }

        this.add(panel1);
        this.pack();
        this.setSize(256, 276);  //Makes it so only one image is visible at once
        this.setResizable(false);
        this.setLocationRelativeTo(null);
        i = RandomRange.Range(1, 4);

        this.remove(panel1);
        panel1.revalidate();
        repaint();
    }

Answer 1

Take out add(panel1) and remove(panel1), and use setContentPane(panel1) instead.