我正在为我的项目创建一个gui。当第一次加载gui时，只有背景可见，所以按钮不可见，但是当鼠标移到它们上面时，它们是可见的。解决这个问题的方法是什么？

public class Home extends JFrame{
//New JPanel 
private JPanel home;

//Creating image url. You must be change url
ImageIcon icon = new ImageIcon("img//home1.jpeg");

//Home Class
public Home(){

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 960, 640);
    setTitle("LoneyTunes Crush");
    home = new JPanel();
    home.setBorder(new EmptyBorder(5, 5, 5, 5));
    home.setLayout(new BorderLayout(0, 0));
    setContentPane(home);

    getContentPane().setLayout(null);
    JLabel background = new JLabel(new ImageIcon("img//giphy."));
    getContentPane().add(background);
    background.setLayout(new FlowLayout());

        //Creating Buttons
    JButton play = new JButton("Play");
    play.setBounds(20, 20, 200, 30);
    JButton setting = new JButton("Settings");
    setting.setBounds(20, 60, 200, 30);
    JButton exit = new JButton("Exit");
    exit.setBounds(20, 100, 200, 30);
       //Adding Buttons
    home.add(play);
    home.add(setting);
    home.add(exit);

            //ActionListeners
    play.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
               home.setVisible(false);
               difficulty.setVisible(true);

            }

          });

    exit.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
            System.exit(1);   

            }

          });

    validate();

}

//Background paint method
public void paint(Graphics g){

    g.drawImage(icon.getImage(), 0, 0, getWidth(), getHeight(), null);

}   

}

主要类别

public class MainClass {
public static Home pencere;

public static void main(String args[]){
    pencere=new Home();
    pencere.setVisible(true);
}

}