Question

Edited this question because of my bad examples.. Here is my updated question:

Would the following be equal in speed and memory allocation:

int b;
for (int i = 0; i < 1000; i++)
    b = i;

and

for (int i = 0; i < 1000; i++)
    int b = i;

Answer 1

No, it wouldn’t.

In the first case you’ve got one variable being assigned 1000 different values – and you end up being able to get hold of the last value (999) after the constructor has completed.

In the second case you’re calling an essentially no-op method 1000 times. The second method has no side-effects and has no return value, so it’s useless. The local variable only “exists” for the duration of the method call, whereas the instance variable in the first example is part of the object, so will live on.

Note that this isn’t restricted to primitives – any other type would behave the same way too.