Confused about class equality

[strtr]

Justin Spahr-Summers Wrote:

> On Fri, 02 Apr 2010 22:36:40 -0400, strtr <strtr at spam.com> wrote:
> 
> You may want to try reducing the code within your "larger project" to 
> the smallest use case where the problem still occurs, because, I agree, 
> the code as written will always result in the same object, since you 
> allocate only one.

The main starting from "I i1 = null;" is actual code from my program. The getI function is also the same and no code resides in between, nor is it multi-threaded. 
Within this setting, how can you manipulate the objects in arr(which is larger in the actual code) to get the strange output?