Null . Unable to understand the null value concept

Question

Dear friends, I am very confusied about the behavior of ----"null"
and i take a String.The String value will come from data base ---- String inputString[This string value will come from database], In data base the value is null.
now i am checking if the string "inputString" is null --will perform a work  if not then perform another work.
so--
inputStringFromUser.equals(null)
System.out.println("In if block");
else
System.out.println("In else block");
but it not working if the data base field is blank.
but if i do ---
inputStringFromUser==null)
System.out.println("In if block");
else
System.out.println("In else block");
it is working fine . why???
please tell me why it is happning.

Answer 1

I did not get any null pointer exception when i test
if(inputStringFromUser.equals(null)
y previous query have cleared.
But i fell i am little bit of confused for this ---
"can't invoke methods on a null reference, that gives
NullPointerException".Can any one please explain.Here's the deal and here's what they're trying to say without any metaphors...
inputStringFromUser is a String object right? the equals method is inherited from the Object object (java.lang.Object)
but if inputStringFromUser is null, it means there's no instance of that String object...so if it's null you cannot access the equals method...this is why you need to use the == operator to see if it's null.
hope that makes sense.