First, you need a variable name in there for it to be legal.
Question: does line 2 initialize 'b' to an empty string?
Line 1 create a String object and assigns it the reference 'a'. Line 2 only creates a reference( 'b' ) to a String object. It will need to be assigned a String object before it can be used. If you try to use before-hand, you'll get a null pointer exception.
On your way in, you might not have noticed the sign on the wall explaining our policy on display names. Let me spell it out fer ya: yer handle has to be a real-lookin' first and last name. Please head over here and fix yours up, please.