The forall() method belongs to the concrete value members of the Class AbstractIterator. It is defined in the class IterableOnceOps. It tests whether a used predicate holds for all the elements of the stated collection. It may not terminate for the infinite sized collection.
Method Definition : def forall(p: (A) => Boolean): Boolean
Return Type : It returns true if the stated collection is empty or if the given predicate p holds for all elements of this collection, else it returns false.