Declare an object inside or outside a loop?

Is there any performance penalty for the following code snippet?

for (int i=0; i<someValue; i++)
{
    Object o = someList.get(i);
    o.doSomething;
}

Or does this code actually make more sense?

Object o;
for (int i=0; i<someValue; i++)
{
    o = someList.get(i);
    o.doSomething;
}

If in byte code these two are totally equivalent then obviously the first method looks better in terms of style, but I want to make sure this is the case.

In today's compilers, no. I declare objects in the smallest scope I can, because it's a lot more readable for the next guy.

To quote Knuth, who may be quoting Hoare:

Premature optimization is the root of all evil.

Whether the compiler will produce marginally faster code by defining the variable outside the loop is debatable, and I imagine it won't. I would guess it'll produce identical bytecode.

Compare this with the number of errors you'll likely prevent by correctly-scoping your variable using in-loop declaration...

There's no performance penalty for declaring the Object o within the loop. The compiler generates very similar bytecode and makes the correct optimizations.

See the article Myth - Defining loop variables inside the loop is bad for performance for a similar example.