String and sum int value of char

[bentho]

1234

[Norm]

Exception is never thrown in body of corresponding try statement

The compiler is complaining that the caught exception is never thrown in the try block. Why are you trying to catch something that is not thrown?

how to return the resulting characters in a string

I don't see where there is anything to return in that method.

Where is the sumOfLastThreeChar method?

You can use arithmetic operators with char variables: 'a' + 4 or 'd' + 'e'