How many ways can convert HashMap to List

Hi,

Today we will talk about how we can convert Hashmap into ArrayList.

1. we have converted keys of HashMap into List.

2. we have converted all values of Map into List.

3. we have converted all entries(key  & values) of HashMap into List.

In below i have explained programme stepwise:- 

package com.neesri.sorting;   import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map.Entry; import java.util.Set;   public class ConvertMapToList {      // we can convert Hashmap into Arraylist through three ways      public static void main(String[] args) {              HashMap<String, Integer> hashmapObj = new HashMap<>();            hashmapObj.put("Zimbabwe", 600);            hashmapObj.put("India", 700);            hashmapObj.put("SriLanka", 400);            hashmapObj.put("Nepal", 800);              // 1-----convert Hashmap Key into List            // using keyset method retun set view            Set<String> setViewOfMapKeys = hashmapObj.keySet();            // convert set into list            List<String> listObj = new ArrayList<>(setViewOfMapKeys);              System.out.println("Hashmap Keys into list------>");            for (String printList : listObj) {                 System.out.println(printList);            }              // 2. Convert Hashmap Values into List              Collection<Integer> values = hashmapObj.values();            List<Integer> list = new ArrayList<>(values);            System.out.println("Hashmap values into List----->");            for (Integer hashmapValuesIntoList : list) {                 System.out.println(hashmapValuesIntoList);            }              // 3. Convert hashmap all entries into List              Set<Entry<String, Integer>> entriesObjSet = hashmapObj.entrySet();            List<Entry<String, Integer>> listEntries = new ArrayList<>(entriesObjSet);              // System.out.println("Hashmap all entries into List======>");            /*             * for(Object obj:listEntries) {             *             * System.out.println(obj); }             */            // OR              /*             * for(Entry<String, Integer> obj:listEntries) {             *             * System.out.println(obj); }             */              // OR            System.out.println("Printing thorough iterator======>");            Iterator<Entry<String, Integer>> iterator = listEntries.iterator();              while (iterator.hasNext()) {                 Entry<String, Integer> entry = iterator.next();                   System.out.println(entry);            }        }   }   ==============OUTPUT====== Hashmap Keys into list------> SriLanka Zimbabwe Nepal India Hashmap values into List-----> 400 600 800 700 Printing thorough iterator======> SriLanka=400 Zimbabwe=600 Nepal=800 India=700

 

Happy Learning :)