1. Iterator Declaration

1. Iterator 

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  Declaration 
  

public interface Iterator

Type Parameters:
E - the type of elements returned by this iterator

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  Iterators are used in Collection framework in Java to retrieve elements one by one. 
  
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  Method Summary 
  

Modifier and Type	Method	Description
default void	forEachRemaining(Consumer action)	Performs the given action for each remaining element until all elements have been processed or the action throws an exception.
boolean	hasNext()	Returns true if the iteration has more elements.
E	next()	Returns the next element in the iteration.
default void	remove()	Removes from the underlying collection the last element returned by this iterator (optional operation).

2. Collection 

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  Declaration: 
  

public interface Collection extends Iterable

Type Parameters:
E - the type of elements returned by this iterator

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  A Collection is a group of individual objects represented as a single unit. Java provides Collection Framework which defines several classes and interfaces to represent a group of objects as a single unit. 
  
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  Method Summary