Java图标文件未显示图像

Question

I am using a Imagebox JFrame to add image, I want to change image in runtime so I add following code but nothing is displayed.

 javax.swing.JFileChooser filechooser = new javax.swing.JFileChooser();
        filechooser.showDialog(this,"ok");
        File f =  filechooser.getSelectedFile();
        txt_Image.setText(f.getName());        
        FileName = f.getPath()+f.getName();
        Image im= Toolkit.getDefaultToolkit().createImage(FileName);
        ImageIcon receivedIcon =null;
        receivedIcon.setImage(im);
        imagebox1.setimageFile(receivedIcon);

the image box code is below

public class imagebox extends JPanel {
    public void setimageFile(Icon icon) {
       imageFile=icon;
    }
    @Override
    public void paint(Graphics g) {
        super.paint(g);
        if (imageFile != null) {            
            Image imageF=  ((ImageIcon)imageFile).getImage();
           g.drawImage(imageF, 0, 0, getWidth(), getHeight(), this);
        } else {
            g.drawLine(0, 0, getWidth(), getHeight());
            g.drawLine(0, getHeight(), getWidth(), 0);
        }
    }
    private Icon imageFile = null;

so why no error showing but I cant get any image in my imagebox

Answer 1

if you only to display the Images then better would be to use Icon/ImageIcon directly, (to avoiding Casting or whatever) put this Icon to the JLabel instead of to the JPanel

if you want change your Icon on Runtime, then you code would be

myLabel.setIcon(myIcon);
revalidate();
repaint(); 

this code must be done on the EDT, otherwise you have to wrap am code lines into invokeLater()

Answer 2

ImageIcon receivedIcon = null;
receivedIcon.setImage(im);

changed to

ImageIcon receivedIcon = new ImageIcon();
receivedIcon.setImage(im);