The project folder is simply the folder in which your program is running. Therefore, when you run your program from eclipse, it looks for the file "Logo.png" in the root directory of the project.
On the other hand, if you export your program and run it in another folder, this folder is located in the root folder of your program, and there it will search for PNG.
If you want your files to be in the res folder, you need to link to PNG accordingly, so, for example, you should write:
launcher.setIconImage(new ImageIcon("res/Logo.png").getImage());
And if you want to make this more general, you should use some kind of configuration mechanism that provides you with the right path for your images. Therefore, you need to change one place when you want to change the folder name.
source share