Collection Basics
What is Collection
Why Collection ?
Collection API
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What is List
What is ArrayList
What is LinkedList
What is Vector
method of vector class in java
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List Advance
ArrayList user defined object
ArrayList internal implementation
LinkedList internal implementation
ArrayList VS LinkedList
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What is HashSet
What is LinkedHashSet
What is TreeSet
Set Advance
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HashSet internal Working
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Set add method
Iterate Collection
Iterate Collection
Advance for loop
What is Iterator
Advantage of Iterator
What is ListIterator
Iterator VS ListLterator
What is Enumeration
Enumeration VS Iterator
What is HashMap
What is LinkedHashMap
What is TreeMap
What is Hashtable
What is WeakHashMap
What is IdentityHashMap
What is Properties file
Map Advance
What is Load-Factor
how to load properties file in java
how to iterate map in java
how to retrieve element of map using keySet
difference between hashmap and hashtable
Map Interview
Internal implementation of HashMap
HashMap Collision
Rehashing Process
Internal working of LinkedHashMap
What is Priority Queue
Concurrent Collections
Concurrent Collections
Concurrentmap in java
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Internal Implementation of CHM
HashMap VS ConcurrentHashMap
What is CopyOnWriteArrayList
What is CopyOnWriteArraySet
Concurrent Map 2
Arraylist VS CopyOnWriteArrayList
put() VS putIfAbsent()
remove() method
replace() method
Collection Sorting
Comparable VS Comparator
Sort by multiple fields
Legacy class
Arrays class
What is Collections
Collection VS Collections
immutable object

what is iterator in java

What is iterator in java

Iterator is an interface which has some method to retrieve elements  from Collection object one by one.

Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined semantics.

We can remove element from collection using Iterator.

Methods of Iterator

  1. boolean hasNext()  :   hasNext() method will return true, if the iterator has elements.
  2. element next()         :   next() method will return next element.
  3. void remove()           :   Use to remove element from collection.

How to create Iterator

Every collection classes provides an iterator() method that returns an iterator to the beginning of the collection.


Iterator iterator = collection_object.iterator();


import java.util.*;
class EnumDemo 
 public static void main(String[] args) 
     ArrayList<Integer> al=new ArrayList<>();
     //creating Iterator object to print element of ArrayList
     Iterator itr=al.iterator();//Iterator created
     while(itr.hasNext())//checking next value 
        System.out.println(;//print next value



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