Matisse properly setting image to panel

I got a problem with NetBeans resource managing while setting images to pannel:

This is my not working code:

try {
    BufferedImage myPicture = ImageIO.read(new File("images/3D.jpg"));
    JLabel picLabel = new JLabel(new ImageIcon(myPicture));
    pnlMain.add(picLabel); //the main and only pannel made by matisse is called pnlMain
} catch (IOException e) {
    JOptionPane.showMessageDialog(this, "Cannot set image");
}

The folder called "images" is in the MAIN project folder. There are several folders: build, nbproject, src and "images".
The problem I have is that the program runs but it doesnt set the image...

Someone suggested me to make another class in different package with this code:

public class PanelImage extends JPanel{
private Image imag;

public PanelImage(Image img){
    if(imagen != null){
        this.imagen = img;
    }
}

@Override
public void paint(Graphics g){
    g.drawImage(img, 0,0, getWidth(), getHeight(), this);
    setOpaque(false);
    super.paint(g);
}
}

But i cant find a proper way of implementing it...

Solution

For your ImagePanel class

super.paint[Component] before all the other stuff.
Don't override paint but instead paintComponent
Don't set properties in paintComponent method ie setOpaque(). Beside, JPanel is opaque by default
Override getPreferredSize() for painting on panels

For loadng images

Make a habit of not reading images from the file system, unless the application is specific to only your machine.

Instead read from the class path and make the image a resource by packaging it into the class path

Change your file structure

ProjectRoot
         src
            images
                 3D.jpg

Read from class path. Use ImageIO to make sure your path is correct. If it's invalid, an exception will be thrown
```
URL url = getClass().getResource("/images/3D.jpg"); 
Image image = ImageIO.read(url);
```

For Netbeans GUI Builder

You can set the label icon using the design tool

Select your label from the navigator or the design view.
Go to the properties window in the right and find the property icon
click the ellipses button to the right of the property and a dialog will appear.
Find your image and select OK (make sure your image is in a package in the src)

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