[ACCEPTED]-Java For-Each Loop : Sort order-loops
Yes. The foreach loop will iterate through 5 the list in the order provided by the
iterator() method. See 4 the documentation for the Iterable interface.
If you look at the Javadoc for List you can see that 3 a list is an "ordered collection" and 2 that the
iterator() method returns an iterator that 1 iterates "in proper sequence".
foreach loop will use the iterator built into 11 the
Collection, so the order you get results in will 10 depend whether or not the
Collection maintains some 9 kind of order to the elements.
So, if you're 8 looping over an
ArrayList, you'll get items in the 7 order they were inserted (assuming you didn't 6 go on to sort the ArrayList). If you're 5 looping over a
HashSet, all bets are off, since 4 HashSets don't maintain any ordering.
If 3 you need to guarantee an order to the elements 2 in the Collection, define a
Comparator that establishes 1 that order and use
Collections.sort(Collection<T>, Comparator<? super T>).
Yes, the Java language specs ensure that
for (Iterator<Whatever> i = c.iterator(); i.hasNext(); ) whatEver(i.next());
is 2 equivalent to
for (Whatever x : c) whatEver(x);
no "change in ordering" is 1 allowed.
You could use a for loop, a la
for (int i = 0; i < myList.length(); i++) if you want 2 to do it in an ordered manner. Though, as 1 far as I know, foreach should do it in order.
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