Thread: Cannot load file from resource using getClass().getResource

For anyone that is having this issue the resolution was to (actually) add the folder to the class path.
Contrary to what you will find via google, the path cannot be added via project properties (apache NetBeans 12.6). At least not under the file/project properties/libraries menu item.
(I cant use the right click method to get to project properties due to NetBeans mishandling screen size and menu items).
Right click 'Libraries' in the project browser and select 'Add Jar/Folder'.


Hello:
Using NetBeans on Ubuntu.
I am trying to load an image into my class but am getting null pointer error.

Exception in thread "main" java.lang.NullPointerException
	at java.desktop/sun.awt.SunToolkit.getImageFromHash(SunToolkit.java:692)
	at java.desktop/sun.awt.SunToolkit.getImage(SunToolkit.java:728)
	at oddcouplepoker.GameCanvas.<init>(GameCanvas.java:23)

I can see the image in my project files list.
h t t p s : //imgur.com/a/dIZpAAT

This is the line that is throwing errors:

this._backgroundImage = Toolkit.getDefaultToolkit().getImage(this.getClass().getResource("resources/images/oddcouple.png"));

From this constructor of a class that extends JPanel:

public class GameCanvas extends JPanel {
    private Image _cardsTileset; 
    private Image _backgroundImage; 
 
    public GameCanvas(String cardsImagePath, String backgroundImagePath) {
        //this. _cardsTileset = Toolkit.getDefaultToolkit().getImage(this.getClass().getResource(cardsImagePath));
        System.out.println(backgroundImagePath);
        this._backgroundImage = Toolkit.getDefaultToolkit().getImage(this.getClass().getResource("resources/images/oddcouple.png"));
        System.out.println("past");
    }

I have been searching all over and I cannot find the answer.

What folders are on the classpath? Where is the resources folder? Is it in one of the folders on the classpath?

The folder resources/images is on the class path I think. I added the folder to Project properties - source package folders.

If you look at the image I linked you can see the image is in the project under resources/images - <default package> - oddcouple.png
I can double click on it there and view it in the source window.
Also the image loads using this ImageIO instead:

try {
            img = ImageIO.read(new File("resources/images/oddcouple.png"));

the image loads using this ImageIO

That says the resources folder is in the current directory when the program executes.
How do you know what folders are on the classpath? Did you print it out?
For example this statement will print out the classpath:

    System.out.println(System.getProperty("java.class.path"));  // show classpath

If the resources folder is on the classpath, then the getResource method should look in the images folder

Thank you Norm, however, sadly the resource is still not being loaded.

The folder was not in my class path.

I added it in and now the output from

 System.out.println(System.getProperty("java.class.path"));  // show classpath

is

/home/noone/NetBeansProjects/OddCouplePoker/resources:/home/noone/NetBeansProjects/OddCouplePoker/resources/images:/home/noone/NetBeansProjects/OddCouplePoker/build/classes
Exception in thread "main" java.lang.NullPointerException
	at java.desktop/sun.awt.SunToolkit.getImageFromHash(SunToolkit.java:692)
	at java.desktop/sun.awt.SunToolkit.getImage(SunToolkit.java:728)
	at oddcouplepoker.GameCanvas.<init>(GameCanvas.java:35)

So the folder is now in the class path. I checked again to make sure the file was in that folder.
But still this persistent error.

Edit:
After some experimentation and juggling paths, actually removing the path to the file seems to have worked:

        this._backgroundImage = Toolkit.getDefaultToolkit().getImage(this.getClass().getResource("/pokertable.png"));

I am not sure why the path cant be included but I am marking this as solved.
Thanks a lot.

The classpath needs to contain the folder that contains the path to the resource file.
If the full path to the file is: :/home/noone/NetBeansProjects/OddCouplePoker/resources/images/pokertable.png
Then the classpath and the path in the getResouce method together point to the file:

cp=home/noone/NetBeansProjects/OddCouplePoker/resources               resPath=images/pokertable.png
cp=home/noone/NetBeansProjects/OddCouplePoker/resources/images    resPath=pokertable.png
cp=home/noone/NetBeansProjects/OddCouplePoker/                          resPath=resources/images/pokertable.png