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About Ilias Tsagklis

Ilias Tsagklis
Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.

Hashtable keys Iterator example

In this example we shall show you how to obtain a Hashtable keys Iterator, that is an iterator of the keys of the Hashtable. To obtain a Hashtable keys Iterator one should perform the following steps:

  • Create a new Hashtable.
  • Populate the hashtable with elements, using put(K key, V value) API method of Hashtable.
  • Invoke keys() API method of Hashtable. It returns an Enumeration of the keys contained in the Hashtable.
  • Iterate through the enumeration, with hasMoreElements() and nextElement() API method of Enumeration,

as described in the code snippet below.

package com.javacodegeeks.snippets.core;
 
import java.util.Hashtable;
import java.util.Enumeration;
 
public class HashtableKeysIterator {
 
  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");
 
    // Enumeration keys() operation returns an Enumeration of keys contained in Hashtable
    Enumeration keysEnumeration = hashtable.keys();
 
    // Iterate through Hashtable keys Enumeration
    System.out.println("Hashtable keys : ");
    while(keysEnumeration.hasMoreElements())

System.out.println(keysEnumeration.nextElement());
  }
}

Output:

Hashtable keys : 
key_3
key_2
key_1

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

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