Converting foreach loop to for loop

Question

I'm really new to Java, and was wondering if someone could help me convert the following to foreach loops into for loops?

Assuming expression is a collection of items:

for(Type x: expression){
   ...
   for(Type y: x.expression){
     .....
    }
}

If `x` is an `int` it doesn't make sense. `x` supposed to be Iterable according to this code. — SHG, Jun 06 '17 at 00:05
The code in the question won't compile (`for(int y: x){...}`) because `x` is an `int`. Is this code you just came up with or did you copy it from somewhere? — Radiodef, Jun 06 '17 at 00:05
I just modeled the loop after something else I am working on, was looking for a general solution. Edited the condition with different type — TestNInja, Jun 06 '17 at 00:06

score 0 · Answer 1 · answered Jun 06 '17 at 00:07

0

expression needs to be some kind of collection of items. The for (Type item : items) loop just iterates over all of them.

To manually loop over the collection you just need the length of the collection and can use:

for (int i = 0; i < collection.size(); i++) { // or .length() if it is an array
  Type item = collection.get(i); // or collection[i] if it is an array
}

Type needs to be the type of the items in the collection.

answered Jun 06 '17 at 00:07

schrej

450
3
10

How would having a nested foreach loop work in this case? – TestNInja Jun 06 '17 at 00:09
1

Well just nest them. If `Type` is another collection it will work the same way. Just use something other than `i` (e.g. `j`) for the nested loop or it'll get overwritten. – schrej Jun 06 '17 at 00:09
1

An enhanced `for` statement does *not* get translated by the compiler to a `for` loop with index variable, because that will not perform for non-array based lists, and don't even work for other types of collections, because they don't have a `get(int)` method. – Andreas Jun 06 '17 at 00:17

Converting foreach loop to for loop

1 Answers1