If I do this
fis = new FileInputStream(new File(\".\").getAbsolutePath() + \"/sudoinput.txt\");
Its trying to write to this location on the ser
If you like to create files in webapps/sudoku/WEB-INF/classes
which is in the end within the created WAR file which can be achieved by putting the files you want into src/main/resources/
This means in other words you need to create the folder src/main/resources
and put the files you like into this directory.