Build it step by step

Every step below leaves a scenario that compiles and runs. If you stop halfway you will have something that works, not something broken. Follow along in Greenfoot rather than reading straight through.

1. Step 1

   On your screen An enhanced for loop with its parts labeled: the type, the variable name, the colon, and the collection.

   for (Enemy e : getObjects(Enemy.class))
   {
       e.turn(180);
   }

   Read the colon as "in": for each Enemy e in this collection.

   `Enemy` is the type of thing coming out. `e` is the name you give each one as it comes. `:` is "in". After it is the collection.

   No counter, no condition, no update. There is no index to get wrong.

2. Step 2

   On your screen The enhanced for and the index loop side by side, doing the same job.

   // Enhanced for
   for (Enemy e : enemies) { e.turn(180); }
   
   // Index loop, same result
   for (int i = 0; i < enemies.size(); i++)
   {
       enemies.get(i).turn(180);
   }

   Same job. The enhanced version is shorter and, more importantly, cannot go off the end, because there is no end to get wrong.

   When you do not need to know WHERE something is, prefer it.

3. Step 3

   On your screen A situation requiring the index, with the position used in the loop body.

   // Needs the index, so an enhanced for cannot do it.
   for (int i = 0; i < enemies.size(); i++)
   {
       enemies.get(i).setLocation(i * 2, 0);
   }

   And here is when you cannot use it. This spaces the enemies out using their POSITION in the list, so the index is part of the job.

   An enhanced for hands you the item and nothing else. No item knows where it sits.

   The other case is removal: you still cannot remove from a collection while looping over it, and the enhanced form does not change that.