What is the size of ” null ” Operator in Java ?

When you write

String st1 = null;
You create a reference “str1″ to an object that still does not exist in the heap, but when you type :


String st2 = "" ;
You create a reference “str2″ to a string object that is already allocated in the heap which preserves the string object size.

if you do that expression

str1 == str2 ;
It should evaluate to false, because you are comparing reference values, which will not be equal.

if you do that expression

if(str1.equals(str2) ){ }
It should throw a NullPointerException because you are trying to access the method equals on a null object ( str1 )

but if you try that expression

if(str2.equals(str1) ) {}
It should return false, because the value of ( str2 ) is an empty string not null object.