I wonder why they didn't just use ! like Ruby does? Is that not allowed in Java? I always mentally say the ! version of a method like a real exclamation (oh no!

I wonder why they didn't just use ! like Ruby does? Is that not allowed in Java? I always mentally say the ! version of a method like a real exclamation (oh no! save!) to make sure I realize it's going to change something. Using $ just seems random.