Image is not being added as background in Java Swing

Question

I have this code and I'm trying to add a picture display as a wallpaper in the background. I used this stackoverflow post as a reference but it didn't work. My image is being added to the panel although not as a background. What possibly is the problem?

Side note, .setLocation() isn't updating the location of buttons either. Thanks in advance!

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import net.miginfocom.swing.MigLayout;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.sql.*;
  
  
class APP extends JPanel
{
    JFrame frame = new JFrame();
    JPanel panel;
  
    class ImagePanel extends JComponent {
        Image image;
        public ImagePanel(Image image) {
            this.image = image;
        }
        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.drawImage(image, 100, 25, this);
        }
    }
  
    public APP(){
  
        JLabel picLabel = new JLabel();
  
  
        try {
            BufferedImage image = ImageIO.read(getClass().getResource("login_bg.jpg"));
            this.setContentPane(new ImagePanel(image));
            picLabel = new JLabel(new ImageIcon(image));
            //picLabel.setBounds(100, 25, 843, 568);
        } catch (IOException e){
            e.printStackTrace();
        }
 
  
        panel = new JPanel();                    // used to do padding like in HTML
        panel.setBorder(BorderFactory.createEmptyBorder(50, 350, 300, 350));
        panel.setLayout(null));
        panel.add(picLabel);
   
   
        frame.add(panel, BorderLayout.CENTER);
        frame.getContentPane();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("Drone Delivery");
        frame.pack();
        frame.setVisible(true);
   
    }
   
}

Answer 1

Still not an MRE, but a little better so I will make more suggestions:

1. There is no main() method to invoke the code
2. There is no need to add 5 components to the panel. One component will demonstrate the problem.
3. In fact you still don't need the panel at all because you still haven't created a JFrame with a background image.

Basic issues with the code:

1. Your logic is attempting to replace the default content pane, with your custom class that paints an image. As I suggested in a "hint" above, if you want a background image then a) the component should extend JPanel, and b) you need to set the layout manager to BorderLayouut in the constructor of the class. Now you will be able to add child components to the panel.

2. You have two instance of a JFrame. Your class extends JFrame and in the constructor you create a new instance of the JFrame. Don't extend JFrame.

3. Your ImagePanel needs to be added to the "frame" created in the constructor.

So the first part of your solution is to simply get this logic working. That is all you need is the JFrame with your ImagePanel added as the content pane of the frame.

Then you move on to the next step.

My image is being added to the panel although not as a background.

Actually it is not added as a background for the reasons given above. What you see is the "JLabel" containing the ImageIcon. Get rid of the label.

//frame.getContentPane().setLayout(new FlowLayout());

The above statement is not needed. You should have already set the layout manager of the "ImagePanel" in the constructor of the class if you followed my hint from above.

frame.add(panel, BorderLayout.CENTER);

Try that and see what happens. You panel will cover the image.

Now try:

    frame.add(panel, BorderLayout.PAGE_START);

and you should see the components at the top of the frame.

You can also add:

panel.setOpaque(false);

and you will see the image below the components.

Answer 2

Theres multipple things wrong with your code, and many bad habits.

1. setLocation() only has permanent effects once you disable the the Layoutmanager. With panel.add(create_btn); you would need a panel with a LayoutManager that does not do any layouting on the Components. I don't know MigLayout, but as LayoutManagers usually do, they lay out the Components. So whenever any change makes MigLayout to layout the panel's Components, any previous manual changes via setSize/setLocation/setBounds etc are lost.

2. You re-use the variable "create_btn", you you actually do not add the first one to any panel, thus it will not appear. Best practice:

• Do not re-use variables
• Initialize as many components as possible in the field with final. This excludes any Components where initialisation throws Exceptions; however they still should be initialized ASAP and made final if possible

3. It looks like you're mixing up the Class APP and the standalone frame you create(frame = new JFrame();). You add the image to the APP, but you never display the frame APP. Instead, inside, you create a second Frame "frame", do NOT add any pictures/labels to it, and then display it. So no wonder the image does not get displayed, as it is in the Frame "APP" that never gets displayed.

/UPDATE: If you want to position the items all by yourself, simply add the line panel.setLayout(null);

Answer 3

I suggest you to use JLabel. This component can have a layout and components, and a background image (by using setIcon(ImageIcon icon)) too.