Question

Possible Duplicates:
Which loop has better performance? Why?
Which is optimal ?
Efficiency of Java code with primitive types

when looping, for instance:

for ( int j = 0; j < 1000; j++) {}; and I need to instantiate 1000 objects, how does it differ when I declare the object inside the loop from declaring it outside the loop ??

 for ( int j = 0; j < 1000; j++) {Object obj; obj =}   

vs

Object obj; 
 for ( int j = 0; j < 1000; j++) {obj =}

It’s obvious that the object is accessible either only from the loop scope or from the scope that is surrounding it. But I don’t understand the performance question, garbage collection etc.

What is the best practice ? Thank you

Answer 1

The first form is better. Limiting the scope of a variable makes it easier for readers to understand where and how it is used.

Performance-wise, there are some small advantages to limited scope as well, which you can read about in another answer. But these concerns are secondary to code comprehension.