Here are some options:
* Ioane: This is the Hawaiian spelling of "John". It's a common name and would be the closest equivalent.
* Ioke: This is a variation of "Ioane", sometimes used as a nickname.
* You could also try using a Hawaiian name that has a similar meaning or sound:
* Kanoa: Meaning "sea traveler"
* Kekoa: Meaning "brave" or "warrior"
* Ikaika: Meaning "strong"
Ultimately, the best way to say "Johnny" in Hawaiian would depend on the specific context and the person you are speaking to.