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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.

Hashtable Iterator example

With this example we are going to demonstrate how to obtain a Hashtable Iterator, that is an iterator of the key value pairs of the Hashtable. In short, to obtain an iterator of the Hashtable’s entries you should:

  • Create a new Hashtable.
  • Populate the hashtable with elements, using put(K key, V value) API method of Hashtable.
  • Invoke the entrySet() API method of Hashtable, that returns a Set containing all the key value pairs of the Hashtable.
  • Obtain an Iterator over the set entries, with iterator() API method of Set.
  • Invoke Iterator’s hasNext() and next() API methods to iterate through the set’s entries.

Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.core;
 
import java.util.Iterator;
import java.util.Hashtable;
import java.util.Set;
 
public class HashtableEntriesIterator {
 
  public static void main(String[] args) {
 
    // Create a Hashtable and populate it with elements
    Hashtable hashtable = new Hashtable();
    hashtable.put("key_1","value_1");
    hashtable.put("key_2","value_2");
    hashtable.put("key_3","value_3");
 
    // Get a set of all the entries (key - value pairs) contained in the Hashtable
    Set entrySet = hashtable.entrySet();


    // Obtain an Iterator for the entries Set
    Iterator it = entrySet.iterator();
    
    // Iterate through Hashtable entries
    System.out.println("Hashtable entries : ");
    while(it.hasNext())

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

Output:

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

 
This was an example of how to obtain a Hashtable Iterator in Java.

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