Java JFrame 为什么不显示图片？

Question

在createWorkPanel()方法中我创建了一个标签并在那里放了一张图片，但图片没有显示在屏幕上。也许有人知道为什么，请告诉我？这是我的代码：import javax.swing.*;import javax.swing.filechooser.FileNameExtensionFilter;import java.awt.*;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.io.File;import java.io.IOException;public class MainWindow extends JFrame {    private JButton button1;    public MainWindow() throws IOException    {        setLayout(new BorderLayout());        createWorkPanel();        setTitle("Графический дизайнер");        //setDefaultLookAndFeelDecorated(true);         setSize(1000,600);       // setLocation(400,100);       // setVisible(true);       // pack(); // automatically size the window to fit its components        setLocationRelativeTo(null); // center this window on the screen        setDefaultCloseOperation(EXIT_ON_CLOSE);    }    public void createWorkPanel() throws IOException    {        setLayout(new FlowLayout());        button1 = new JButton("Load Images");        button1.setActionCommand("Button 1 was prassed!");        add(button1);        ActionListener  actionListener = new AbstractAction() {            @Override            public void actionPerformed(ActionEvent e) {                File fImg = MyFileChooser.chooseFile("Image Files (png & jpg)", "png", "jpg");                if (fImg != null)                {                    JLabel background=new JLabel(new ImageIcon(fImg.getAbsolutePath()));                   // background.setLayout(new FlowLayout());                    add(background);                    System.out.println(" файл создан");                }            }        };        button1.addActionListener(actionListener);