What are different ways of iterating over keys, values and entry in Map?

What are different ways of iterating over keys, values and entry in Map?

Answer: 
Create and put key-value pairs in HashMap

package com.tutorial4u; import java.util.HashMap; import java.util.Iterator; import java.util.Map; public class HashMapDemo {      public static void main(String[] args) {            Map hashMap = new HashMap();            hashMap.put(11, "CSS");            hashMap.put(21, "IT");            hashMap.put(31, "ECE");            hashMap.put(41, "EEE");      }      }

Iterate over keys :-

hashMap.keySet().iterator() method returns iterator to iterate over keys in HashMap.

Iterator keyIterator =hashMap.keySet().iterator();            while(keyIterator.hasNext()){            System.out.println(keyIterator.next());        }

/*OUTPUT
21
41
11

31
*/
Iterate over values :-

hashMap.values().iterator() method returns iterator to iterate over keys in HashMap.

Iterator valueIterator=hashMap.values().iterator();            while(valueIterator.hasNext()){            System.out.println(valueIterator.next());        }

/*OUTPUT
IT
EEE
CSS

ECE
*/

Iterate over Entry-

hashMap.entrySet().iterator() method returns iterator to iterate over keys in HashMap.

Iterator entryIterator=hashMap.entrySet().iterator();            while(entryIterator.hasNext()){            System.out.println(entryIterator.next());        }

/*OUTPUT
21=IT
41=EEE
11=CSS
31=ECE

*/