Search:

I can't really recommend any good Java books in particular, but I'm sure there are some good ones out there (sounds like you found one already). I learned Java mostly through classes, the internet,...

parseInt converts the string "3" to an integer 3, it can't convert the string "three" to an integer 3.

What's the exception it's throwing?

Yep, that's the simple solution. The same mechanism can be used to filter out numbers out of the range.

You forgot the numbers 11 through 19.

Rather than manually converting a String "22" to "twenty-two", it's much simpler to convert the integer 22 to "twenty-two" through a little clever math.
...