java - Isn't iterator a built-in function, why do I have to import it? -

// inside class  public void playround() {         iterator<player> itr = players.iterator();         while(itr.hasnext()){              player player =itr.next();              player.play(par);         }         // supply code!     } 

it says :exception in thread "main" java.lang.error: unresolved compilation problem: iterator cannot resolved type

isn't iterator built in function?

i forced import :

import java.util.iterator; 

if want resolve issue, there way avoid importing iterator. reason why cannot import iterator though save me lot of time, because project not allowed import other import java.util.arraylist;

furthermore, using eclipse write code.

in word - no. there's nothing "magical" iterator. it's class java.util package, , if want use should either import or reference qualified name:

java.util.iterator<player> itr = players.iterator(); 

but guess forbidden requirements. instead, use enhanced for loop:

for (player player : players) {     player.play(par); } 

edit:
@yshavit noted in comments, since players list , not old iterable, can access elements directly via index, meaning use "old fashioned" for loop:

for (int = 0; < players.size(); ++i) {     players.get(i).play(par); }