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about == equals

krussi rong
Ranch Hand

Joined: Jan 30, 2002
Posts: 62
Hi,
here is the question:
Double a = new Double(Double.NaN);
Double b = new Double(Double.NaN);
if(Double.NaN == Double.NaN)
System.out.println("True");
else
System.out.println("False");
if(a.equals(b))
System.out.println("True");
else
System.out.println("False");

So why the answer is False
True.
if Double.NaN == Double.NaN is False,
How the a.equals(b) comes True.
and I really don't know why Double.NaN == Double.NaN if False. and what is NaN?
Thanks
Krussi
Corey McGlone
Ranch Hand

Joined: Dec 20, 2001
Posts: 3271
Check out the API Spec for Double. In particular, check out the description of the equals() method.
Corey


SCJP Tipline, etc.
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: about == equals