java - Nullpointer exception

Question

There is a possiblity that this may be a dupicate question. I initialize a String variable to null.I may or may not update it with a value.Now I want to check whether this variable is not equal to null and whatever I try I get a null pointer exception.I can't afford to throw nullpointer exception as it is costly.Is there any workaround that is efficient.TIA

Answer 1

If you use

if (x == null)

you will not get a NullPointerException.

I suspect you're doing:

if (x.y == null)

which is throwing because x is null, not because x.y is null.

If that doesn't explain it, please post the code you're using to test for nullity.