Which loop has better performance? Why?

Question

String s = \"\";
for(i=0;i<....){
    s = some Assignment;
}

or

for(i=0;i<..){
    String s = some Assignment;
}

Answer 1

In theory, it's a waste of resources to declare the string inside the loop. In practice, however, both of the snippets you presented will compile down to the same code (declaration outside the loop).

So, if your compiler does any amount of optimization, there's no difference.