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Float.POSITIVE_INFINITY...?

Prashant Neginahal
Ranch Hand

Joined: Dec 04, 2002
Posts: 76
Hi All,
int j = (int)Float.POSITIVE_INFINITY;
j==Integer.MAX_VALUE; It gives true
then,
short i = (short)Float.POSITIVE_INFINITY;
i == Short.MAX_VALUE;It gives false
I really not understanding these two cases, will anyone please explian me.?
-----------
Prashant


--------------<br />Prashant<br />SCJP-91%
Peter den Haan
author
Ranch Hand

Joined: Apr 20, 2000
Posts: 3252
Beware of casts to integer types other than long or int. They do not work the way you might think.
When you convert a float (or double) to a byte, short, or char, the number is first converted to an int and then truncated to a short.
So what happens in this case is that Float.POSITIVE_INFINITY is converted to Integer.MAX_VALUE (01111111111111111111111111111111), then this value is simply truncated to a 16 bit short value (1111111111111111). The result is therefore -1 rather than Short.MAX_VALUE (0111111111111111).
The details are in the JLS section 5.1.3 Narrowing Primitive Conversions.
- Peter
 
It is sorta covered in the JavaRanch Style Guide.
 
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