Java's Iterable Interface

The Iterable interface (java.lang.Iterable) is one of the root interfaces of the Java collection classes. The Collection interface extends Iterable, so all subtypes of Collection also implement the Iterable interface.
A class that implements the Iterable can be used with the new for-loop. Here is such an example:

List list = new ArrayList();

for(Object o : list){
    //do something o;    
}

The Iterable interface has only one method:

public interface Iterable<T> {
  public Iterator<T> iterator();    
}

How you implement this Iterable interface so that you can use it with the new for-loop, is explained in the text Implementing the Iterable Interface, in my Java Generics tutorial.