Array constructors

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11-05-2010, 04:26 PM
StanO

Array constructors

Hello,

I have a beginner Java question about array constructors.

This is okay:

final int[] blah = { 45, -45 };
for (int i : blah ) { ; }

This is illegal but would be sweet:

for (int i : { 45, -45 } ) { ; }

This works but is ugly and greater space/time?

for (int i : new int[] { 45, -45 } ) { ; }

Comments?

TIA!
StanO
11-05-2010, 04:38 PM
JosAH

Quote:

Originally Posted by StanO

Comments?

Yup, should { 45, -45 } be an int array or a byte array or a short array or what? The compiler can't decide that for you.

kind regards,

Jos
11-05-2010, 06:14 PM
Zack

Quote:

Originally Posted by StanO

This works but is ugly and greater space/time?

for (int i : new int[] { 45, -45 } ) { ; }

I don't see how it's greater space/time. Either way, the VM allocates an array of two Integers. Whether or not that's explicitly declared has no effect on how much space or time it takes to create the array. (Also agree with what Jos said.)
11-05-2010, 08:14 PM
StanO

You're sure that the compiler will create that array object just once and reuse it the next time the code that includes the loop is called?

If it gets created each time the loop is called, then it is not-only ugly...

Clearly, the first case will only get constructed once.

Thanks again!
11-05-2010, 09:01 PM
Zack

Quote:

Originally Posted by StanO

You're sure that the compiler will create that array object just once and reuse it the next time the code that includes the loop is called?

If it gets created each time the loop is called, then it is not-only ugly...

It will only create it once, but what I'm saying is that it has no advantage or disadvantage over just doing {45,-45} (if it were legal) in the first place. Both have to allocate the same amount of data at the same time and for the same purpose.