Note that it almost never makes sense to spend too much time on micro-optimizations like this. The
Java compiler and garbage collector are pretty smart and complicated pieces of software which apply a lot of smart optimizations, often more complicated than you've ever imagined. It's very hard to say which construction is better without knowing exactly how the compiler and garbage collector work.
If you really want to find out which is "better",
you should write a
test program, run it and measure the performance. I'd bet that with the code above, the difference between the two approaches is immeasureably small, so it really doesn't matter what approach you take.