How to Check null in double

[Muhammad Saifuddin]

hi all
can any body body tell me how i check a null value in double type variable..?

double value

if(value (???) null)

thanx



[ April 08, 2006: Message edited by: saif uddin ]

[pascal betz]

you can not check a primitive (double, float, long, int, char, short, byte, boolean) datatype for null.

primitives have a value always. you can only check references to Objects for null. there is a wrapper Object for each of the primitives (Double, Float,, Long, Integer, ...) if you use these, then you can check for null.

if you use java 1.5/5.0 then you should read about "autoboxing/unboxing", a feature which allows you to write code like this:

int i = new Integer(3);
Long l = 1L;

here primitives and wrapper objects are mixed.
of course there are a some rules when/how autoboxing happens (e.g. what if you assign null to a primitive and so on). and it's important you understand these...


pascal

[Muhammad Saifuddin]

Thanks for the explanation!
[ July 25, 2006: Message edited by: saif uddin ]

[Tony Morris]

primitives have a value always.

..assuming they are definitely assigned.

[Adeel Ansari]

Originally posted by Tony Morris:
..assuming they are definitely assigned.

worth mentioning.