监听事件中无法改变窗口的背景图片

我想实现的是在一个界面上有一个按钮，按下这个按钮后会改变这个界面的背景图片。但是我把那个改变图片的代码加入监听事件后，按下按钮并没有反应，图片并未改变。但是我如果未加入监听事件，直接把改变背景的代码放在后边，运行后背景就变了。我想知道这个该如何解决，谢谢各位大佬

import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class test extends JFrame implements ActionListener
{
private JButton but2;

public JLabel imgLabel;

public test()
{
    Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
    int width = (int)dim.getWidth();
    int height = (int)dim.getHeight();
    this.setSize(dim);
    this.setVisible(true);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setLayout(null);

    ImageIcon img = new ImageIcon("C:\\Users\\Cy\\Pictures\\1.png");

    JLabel imgLabel = new JLabel(img);

    this.getLayeredPane().add(imgLabel, new Integer(Integer.MIN_VALUE));
    imgLabel.setBounds(0, 0, img.getIconWidth(), img.getIconHeight());
    Container contain = this.getContentPane();
    ((JPanel) contain).setOpaque(false); 

    Color c=new Color(2,2,255);     
    but2=new JButton();
    this.add(but2);
    but2.setBackground(c);
    but2.setOpaque(false);
    but2.setBorderPainted(false);

    but2.setBounds(width-height/10, height*2/7-height/10, 100,100);
    ImageIcon icon2 =new ImageIcon("C:\\\\Users\\\\Cy\\\\Pictures\\\\cal.png");
    but2.setIcon(icon2);



    /*
    ImageIcon img2 = new ImageIcon("C:\\Users\\Cy\\Pictures\\star.png");
    imgLabel.setIcon(img2);
    imgLabel.setBounds(-60, -50, img.getIconWidth(), img.getIconHeight());




    but2.addActionListener(this);

}

public void actionPerformed(ActionEvent e)
{
    if(e.getSource() == but2)
    {

        JLabel imgLabel=new JLabel();

        ImageIcon img2 = new ImageIcon("C:\\Users\\Cy\\Pictures\\star.png");

        imgLabel.setIcon(img2);

        imgLabel.setBounds(0, 0, img2.getIconWidth(), img2.getIconHeight());


    }

}

}

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