



I can't use the method from another class
the code above is from the method of the main class or main java file(some sort of runner java file)
the "addSong()" method(Custom method) is from another class and another java file but that and the main java file are in the same folder. The first pic was when it is just "void addSong(String input){...}" and the 3rd pic is when the method is "public void addSong(String input){...}".
I fail to see what I did wrong here.