Reading files with Intellij idea IDE

Just move the file directly to the project folder which calls Java (and something under the blue-blurred stripe you made :P).

If that doesn’t help, then move the test123.txt file to FirstJavaProgram directory.

You can also change filename to one of these:

1. src/test123.txt

2. FirstJavaProgram/src/test123.txt

I am not sure which one will be fine in your case.