Convert HashMap to Array List

 Conver HashMap into Array List

package com.tutorials.maptolist;

import java.util.ArrayList;

import java.util.Collection;

import java.util.HashMap;

import java.util.List;

import java.util.Map.Entry;

import java.util.Set;

public class HashMapToList {

     public static void main(String[] args) {

          // Conversion Of HashMap Keys Into ArrayList

          // public abstract Set<K> keySet();

          HashMap<String, String> map = new HashMap<String, String>();

          map.put("Paras", "Chawla");

          map.put("Nonu", "Gupta");

          Set<String> set = map.keySet();

          List<String> keyList = new ArrayList<String>(set);

          System.out.println(keyList);

          // Conversion Of HashMap values Into ArrayList

          // public abstract Collection<V> values();

          Collection<String> values = map.values();

          List<String> valueList = new ArrayList<String>(values);

          System.out.println(valueList);

          // Conversion Of HashMap’s Key-Value Pairs Into ArrayList.Creating an ArrayList Of Entry objects

          // entrySet : Returns a Set view of the mappings contained in this map.

          // public abstract Set<Entry<K, V>> entrySet();

          Set<Entry<String, String>> entrySet = map.entrySet();

          ArrayList<Entry<String, String>> listOfEntry = new ArrayList<Entry<String, String>>(

                   entrySet);

          for (Entry<String, String> entry : listOfEntry)

              System.out.println(entry.getKey() + " : " + entry.getValue());

          System.out.println(listOfEntry);

     }

}

Output :

[Nonu, Paras]

[Gupta, Chawla]

Nonu : Gupta

Paras : Chawla

[Nonu=Gupta, Paras=Chawla]