In this example we shall show you how to get an Enumeration from a Collection. We are using an ArrayList, but the same API applies to any type of Collection implementation class e.g. HashSet, TreeSet, LinkedHashSet, LinkedList, Vector etc. To get an Enumeration from an ArrayList one should perform the following steps:
- Create an ArrayList.
- Populate the arrayList with elements, with
add(E e)API method of ArrayList. - Invoke the
enumeration(Collection c)API method of Collections, to get the enumeration object over the specified Collection, which is an ArrayList in the example. - Get the elements of the enumeration, with
hasMoreElements(),nextElement()API method of Enumeration,
as described in the code snippet below.
package com.javacodegeeks.snippets.core;
import java.util.Enumeration;
import java.util.ArrayList;
import java.util.Collections;
public class EnumerationOverCollection {
public static void main(String[] args) {
/*
Please note that the same API applies to any type of
Collection implementation class e.g.
HashSet, TreeSet, LinkedHashSet, LinkedList, Vector etc
*/
// Create an ArrayList and populate it with elements
ArrayList arrayList = new ArrayList();
arrayList.add("element_1");
arrayList.add("element_2");
arrayList.add("element_3");
arrayList.add("element_4");
arrayList.add("element_5");
// static Enumeration enumeration(Collection c) method returns the enumeration object over the specified Collection
Enumeration enumeration = Collections.enumeration(arrayList);
System.out.println("Enumerating through ArrayList");
while(enumeration.hasMoreElements())
System.out.println(enumeration.nextElement());
}
}
Output:
Enumerating through ArrayList
element_1
element_2
element_3
element_4
element_5
This was an example of how to get an Enumeration from a Collection in Java.
