A DESCRIPTION OF THE PROBLEM :
Hello,

Sorry for my bad english.

I think there is a mistake in the documentation of String class here : https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#indexOf(int)

If you go to the indexOf function definition, it is written that it takes in parameter an "int ch"... but I think this is a character.

Original : "public int indexOf(int ch)"
New : "public int indexOf(char ch)"

Furthermore, you wrote it is a character in the subsection "Parameters".

Hope it helps.

Greetings,
Maxime SENDEN