"for each" loop - under the hood question

Question

Question about the for each loop. Is it optomized? I think this is a poor use of memory management -
for (int i = 0; i < stop; i++) {
Object obj = new Object();
doSomething(obj);
}And this is the ideal, using the same object -
Object obj = new Object();
for (int i = 0; i < stop; i++) {
doSomething(obj);
}So underneath the hood, which is the for each loop comparable to? I love the syntax, it's very clean-looking in the code, but at the same time I don't want to hurt performance.

Answer 1

Question about the for each loop. Is it optomized? I
think this is a poor use of memory management -
for (int i = 0; i < stop; i++) {
Object obj = new Object();
doSomething(obj);
}And this is the ideal, using the same object -
Object obj = new Object();
for (int i = 0; i < stop; i++) {
doSomething(obj);
}So underneath the hood, which is the for each loop
comparable to? I love the syntax, it's very
clean-looking in the code, but at the same time I
don't want to hurt performance.That depends on YOU. You CANNOT write a for-each loop for the code you provided. A for-each loop requires an Iterable. (I think that's what it requires--it at least requires something to iterate over, not just an index variable as you have.)
Consider the following, however:
Object o1 = new Object();
for (Foo foo : fooList) {
    Object o2 = new Object();
     foo.doStuff(o1, o2);
} It will be equivalent to this:Object o1 = new Object();
for (Iterator iter = foo.iterator(); iter.hasNext();) {
    Foo foo = (Foo)iter.next();
    Object o2 = new Object();
    foo.doStuf(o1, o2);
} How could it be any different? It has to keep the behvior of the "old fashioned" iteration.