Array

[Abhi vijay]

Source: Inquisition

class Q55
{
public static void main(String[] args)
{
int[] a={11,12,13,14};
int[] b={0,1,2,3};
System.out.println(a[(a=b)[3]]);//1
}
}
The answer is 14. The assignments a=b, is local to the print statement??

[Ravikanth kolli]

No the assignment is to the complete method.This can be verified using the hashcode, of a and b.

[patrick avery]

The interesting thing is that even though 'a' acts like it has been equated to 'b' during the inner evaluation, i.e. (a=b)[3], part of the expression (resulting in a value of 3), it retains it's old identity in the outer evaluation part of the expression (resulting in a value of 14), then going forward it reverts to being equal to 'b' again, as shown in the extra line added below.

----------------------------------------------
class Q55 {
public static void main(String[] args) {
int[] a={11,12,13,14};
int[] b={0,1,2,3};
System.out.println(a[(a=b)[3]]); // prints 14 (from old a array)
System.out.println(a[0]); // prints 0 (from new a array)
}
}
----------------------------------------------

[Campbell Ritchie]

That presumably means the [] operator takes precedence over the = inside.

[meera kanekal]

I still don't understand how a[(a=b)[3]] evaluates to 14. Can someone please explain? I understand that a[3] is 14. What does the assignment of a=b evaluate to?
Ravikanth could you please explain what you mean by "No the assignment is to the complete method.This can be verified using the hashcode, of a and b"?
And Patrick how can it print 0 for--> System.out.println(a[0]); // prints 0 (from new a array)
since the assignment is only in the print statement?
Thanks,
Meera

[meera kanekal]

Ok I think I understand what is going on here.
(a=b)[3] evaluates to 3. So a[(a=b)[3]] is 14.
But I thought the assignment a=b would be local. apparently not. Could someone explain why it is not?
Thanks,
Meera

[Fabio Nascimento]

Local things happens between { } not between ( ).

I knew that you could use ( ) everywhere in Java, but that is ugly O_O