Get All Values of Hashtable in Java Example

This example shows how to get all values stored in the Hashtable in Java. This example also shows how to get all Hashtable values using the elements method and values method.

How to get all the values of Hashtable in Java?

There are a couple of ways using which we can get all the values stored in the hashtable object.

1. Using the elements method

The Hashtable elements method returns an Enumeration over the hashtable values.

1	public Enumeration<V> elements()

Once we get the enumeration, we can iterate through all the values of the hash table using the hasMoreElements and nextElement methods as given below.

import java.util.Enumeration;

import java.util.Hashtable;

public class HashtableGetAllValuesExample {

public static void main(String[] args) {

Hashtable<Integer, String> hashtable = new Hashtable<Integer, String>();

hashtable.put(1, "One");

hashtable.put(2, "Two");

hashtable.put(10, "One");

hashtable.put(20, "Two");

* To get all values stored in the hashtable

* use the elements method

Enumeration<String> values = hashtable.elements();

//iterate the values

while( values.hasMoreElements() ){

System.out.println( values.nextElement() );

}

Output

One

Two

One

2. Using the values method

The Hashtable values method returns a Collection view of all the values contained in the hashtable object.

1	public Collection<V> values()

The Collection object is a view that is backed by the original hashtable object. That means any changes you make to this view will also be reflected in the original hashtable object, and vice versa.

We can get an iterator over values using the iterator method of the Collections. Once we get an iterator, we can iterate through the values using the hasNext and next methods as given below.

Hashtable<Integer, String> hashtable = new Hashtable<Integer, String>();

hashtable.put(1, "One");

hashtable.put(2, "Two");

hashtable.put(10, "One");

hashtable.put(20, "Two");

* To get a Collection view of all the values

* stored in the hashtable object, use the

* values method

Collection<String> values = hashtable.values();

//get an iterator

Iterator<String> itr = values.iterator();

//iterate

while( itr.hasNext() ){

System.out.println( itr.next() );

}

Output

One

Two

One

The elements vs values method

The elements method returns an Enumeration while the values method returns a Collection view.
We can directly iterate over elements using the Enumeration while we need to get the iterator from Collection object to iterate through elements
The elements method is inherited from the JDK 1.0 Dictionary class while the values method was introduced in Java 2.0 when the Hashtable class implemented the Map interface.
We can remove the elements while iterating using the iterator which cannot be done using the Enumeration.

This example is a part of the Hashtable in Java Tutorial with Examples.

Please let me know your views in the comments section below.

References:
Java 8 Hashtable Documentation

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Rahim

I have a master's degree in computer science and over 18 years of experience designing and developing Java applications. I have worked with many fortune 500 companies as an eCommerce Architect. Follow me on LinkedIn and Facebook.