Java检查变量是否已初始化

So I'm pretty new to Java. Been taking a class at my college, this first semester is focussing on getting the syntax down and some of the basic ideas right while using a java library called ObjectDraw. Next semester we're going to start getting away from ObjectDraw and into core Java some more. Anyways I have run into a few problems where I need to use something similar to php's isset function. I know php and java are EXTREMELY different so I shouldn't try to compare them but php is my only basis of previous knowledge on something similar to programming. I just wondered if there was some kind of method that would return a boolean value for whether or not an instance variable had been initialized or not. For example...So I'm pretty new to Java. Been taking a class