Different Ways of Looping the Map in Java

INTRODUCTION

There are multiple ways to loop through a Map and display the Key and Value. They are:

1. Using EntrySet
2. Using KeySet
3. Using Iterator
4. Using Map Values

Below example will provide different ways of looping the Map Keys and its values.

EXAMPLE

import java.util.Collection; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Map.Entry; import java.util.Set; public class LoopingMap {  public static void main(String[] args) {    Map<String, String> map = new HashMap<String, String>();    map.put("1000", "Ranjith");    map.put("2000", "Sekar");    map.put("3000", "Bala");    map.put("4000", "Kumar");    map.put("5000", "Rekha");    // Way 1: Using EntrySet    System.out.println("===1. Using Map's EntrySet===");    Set<Map.Entry<String, String>> entries = map.entrySet();    for (Map.Entry<String, String> entry : entries) {      System.out.println(entry.getKey() + " >> " + entry.getValue());    }    // Way 2: Using keySet    System.out.println("\n===2. Using Map's KeySet===");    Set<String> str = map.keySet();    for (Object obj : str) {      System.out.println(obj.toString() + " >> " + map.get(obj.toString()));    }    // Way 3: Using Iterator    System.out.println("\n===3. Using Iterator===");    Iterator<Entry<String, String>> iterator = map.entrySet().iterator();    while (iterator.hasNext()) {      Entry<String, String> entry = iterator.next();      System.out.println(entry.getKey() + " >> " + entry.getValue());    }    // Way 4: Using Map's Value (Iterators only Values in the Map)    System.out.println("\n===4. Using Map's Values===");    Collection<String> collection = map.values();    Iterator<String> itr = collection.iterator();    while (itr.hasNext()) {      System.out.println(itr.next());    }  } }

OUTPUT

===1. Using Map's EntrySet=== 5000 >> Rekha 3000 >> Bala 4000 >> Kumar 1000 >> Ranjith 2000 >> Sekar ===2. Using Map's KeySet=== 5000 >> Rekha 3000 >> Bala 4000 >> Kumar 1000 >> Ranjith 2000 >> Sekar ===3. Using Iterator=== 5000 >> Rekha 3000 >> Bala 4000 >> Kumar 1000 >> Ranjith 2000 >> Sekar ===4. Using Map's Values=== Rekha Bala Kumar Ranjith Sekar