With autounboxing, this statement will automatically work:
int myPrimitive = (Integer) doIt();
But if I want to explicitly convert from an Integer to an int here in a single line, where do I have to put the parentheses?
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54answers:
2
+4
A:
You could do this :
int myPrimitive = (int) (Integer) doIt();
But as you said, auto-unboxing will get that for you.
A bad example to show that chain casts work (don't ever use this code) :
Map notReallyAMap = (Map) (Object) new String();
The thing with chain casts, is that wherever you use it, either the cast is legit, and you can remove intermediaries; or the cast will simply cause a ClassCastException. So you should never use it.
Colin Hebert
2010-10-11 20:29:39
A cast from an Integer to an int *IS* a case of auto-unboxing. Integer.intValue() method will do an explicit unboxing. But I do agree with one thing : **Chain cast = don't ever use this!** (+1 for that)
Eric-Karl
2010-10-11 23:26:50
@Eric-Karl, It is an unboxing I agree, but not really an automatic one.
Colin Hebert
2010-10-12 07:18:40
[Here is a document](http://jcp.org/aboutJava/communityprocess/jsr/tiger/autoboxing.html) about autoboxing, which tells that explicit cast/conversion is called boxing whereas autoboxing would be automatically done.
Colin Hebert
2010-10-12 07:27:38
I stand corrected. :)
Eric-Karl
2010-10-12 12:10:06
+2
A:
Either the compiler unboxes the Integer for you, or you do it yourself - this cannot be avoided.
So you need to either do
int myPrimitive = ((Integer) doIt()).intValue();
or more simply, change doIt() to return an int since you seem to want to deal with ints rather than (null-able) Integers.
matt b
2010-10-11 20:47:21