Java ImageIO.read(getClass().getResource()) returns null

Question

The line ``` andImg = ImageIO.read(getClass().getResource("gate_and.png")); ``` fails with ``` Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: input == null! ``` I'm using Eclipse and in the navigation view under the bin folder there is the file gate_and.png, suggesting that the file is in the build path. In the package explorer view I have ``` project/src/view/class - This is the class that has the code above. ``` and ``` project/images/gate_and.png ``` I right clicked the project folder > build path > link source to add the images folder as a source, doing this again provides a confirmation msg that says images is already in the source. I have also tried changing gate_and.png to images/gate_and.png and /images/gate_and.png, but since the image gate_and.png is in the bin folder, I think the original is correct.

Accepted Answer

Assuming your class is in package `view.random.name`, then

```
getClass().getResource("gate_and.png")
```

will look for the resource in

```
/view/random/name/gate_and.png
```

relative to the root of the classpath. You apparently don't have a resource by that name there.

By setting `project/images` as a build path entry, Eclipse will include everything in it on the classpath. Therefore, your resource will appear at

```
/gate_and.png
```

You can access it with

```
getClass().getResource("/gate_and.png")
```

Note the leading `/` that means start looking at the root of the classpath, ie. it's an absolute path.

All these rules are explained in the javadoc.

Java ImageIO.read(getClass().getResource()) returns null

Solution

Problem