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About Byron Kiourtzoglou

Byron Kiourtzoglou
Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.

HashMap Iterator example

In this example we shall show you how to use a HashMap Iterator. To use a HashMap one should perform the following steps:

  • Create a new HashMap.
  • Populate the hashMap with elements, with the put(K key, V value) API method of HashMap.
  • Invoke the entrySet() API method of the HashMap to get a Set of all the entries (key – value pairs) contained in the HashMap.
  • Obtain an Iterator for the entries Set, and iterate through the HashMap entries,

as described in the code snippet below.

package com.javacodegeeks.snippets.core;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
 
public class HashMapIterator {
 
  public static void main(String[] args) {
 
    // Create a HashMap and populate it with elements
    HashMap hashMap = new HashMap();
    hashMap.put("key_1","value_1");
    hashMap.put("key_2","value_2");
    hashMap.put("key_3","value_3");
 
    // Get a set of all the entries (key - value pairs) contained in the HashMap
    Set entrySet = hashMap.entrySet();
    
    // Obtain an Iterator for the entries Set
    Iterator it = entrySet.iterator();
  
    // Iterate through HashMap entries
    System.out.println("HashMap entries : ");
    while(it.hasNext())

System.out.println(it.next());
  }
}

Output:

HashMap entries : 
key_3=value_3
key_2=value_2
key_1=value_1

 
This was an example of how to use a HashMap Iterator in Java.

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