That they don't know how to throw an exception in Java doesn't mean they don't know what an exception is and how it can be used to control program flow -- why not ask them about it? All it tells you is that they have no professional experience as a Java programmer... which you already knew before interviewing them.
Well, why didn't they look that up before the interview? Because they didn't know that'd be the one detail out of thousands of bits of syntax and library knowledge you pick up when you do work in a certain language. The only way to pick them all up is experience -- and again -- you already know they don't have it.
If you don't want to hire college graduates for a junior developer position without work experience, then take junior off the title and bump up the pay. Add a work experience requirement. It sounds like you'll be a lot happier with that.
Well, why didn't they look that up before the interview? Because they didn't know that'd be the one detail out of thousands of bits of syntax and library knowledge you pick up when you do work in a certain language. The only way to pick them all up is experience -- and again -- you already know they don't have it.
If you don't want to hire college graduates for a junior developer position without work experience, then take junior off the title and bump up the pay. Add a work experience requirement. It sounds like you'll be a lot happier with that.