java - Images will not work in a .jar file

Question

When a JAR of an application is created, the images in the application no longer appear. An example of our code for loading images is:

ImageIcon placeHolder = new ImageIcon("src\Cards\hidden.png");

We have no idea why this is happening. The application runs as expected if we do not compress it to a JAR; as a JAR, the images simply disappear. We also tried using URLs instead of ImageIcons, but that just causes the program not to run at all.

Any ideas?

EDIT: We are putting the image files into our JAR file in the correct paths, so that's not the problem.

Answer 1

Check the API for the constructor you're calling. The string you pass in is a file path - when the resources are packaged in a JAR, there is no file on the filesystem containing the image, so you can't use this constructor any more.

Instead you'd need to load the resources from a stream, using the classloader, and pull them into a byte array:

byte[] buffer = new byte[IMAGE_MAX_SIZE];
InputStream imageStream = getClassLoader().getResourceAsStream("srcCardshidden.png");
imageStream.read(buffer, 0, IMAGE_MAX_SIZE);
ImageIcon placeHolder = new ImageIcon(buffer);

Needs more exception and edge-case handling, of course, but that's the gist of it.