java.lang.IllegalArgumentException: input == null! when using ImageIO.read to load image as bufferedImage

Question

This is a question that has been asked like 100 times on this site, but I have looked at all of them and even though they all were solved, none of the solutions worked for me.

Here's what my code looks like:

public Button1(Client client, String imgName) {
    this.client = client;   

    try {
        this.icon = ImageIO.read(this.getClass().getResourceAsStream("/resources/" + imgName));
    } catch (IOException e) {
        e.printStackTrace();
    }

When the code runs it results in the following error:

Exception in thread "main" java.lang.IllegalArgumentException: input == null!
at javax.imageio.ImageIO.read(Unknown Source)

The string imgName is passed to the constructor from a child class and is the name of an image (e.g. image.png). I also have made sure that my resources folder is in the root of the project folder, and is included as a source folder in the eclipse project. I've also made sure that System.getProperty("user.dir") points to the correct location. I have also tried using getResource() instead of getResourceAsStream(), but it still does not work.

Answer 1

Try using this:-

this.icon = ImageIO.read(new FileInputStream("res/test.txt"));

where res folder is present at the same level as your src folder. Also, if you notice, the slash / before the res folder name was removed.

Answer 2

I know this is pretty old, but I just had the same issue.

Check to make sure that your image extensions aren't capital.

In my resources folder for images I had "enemy.PNG", but I was trying to load "enemy.png" which you would think would work but doesn't.

so, just make your extensions aren't capitalized.