Convert an enumeration to Iterable in Java

Write a method that takes an enumeration as input and return an Iterable as output.

 

Signature

public static <T> Iterable<T> toIterable(final Enumeration<T> enumeration)

 

Find the below working application.

 

EnumerationToIterable.java

package com.sample.app.collections;

import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Vector;

public class EnumerationToIterable {

	/**
	 * Convert an {@link Enumeration} to an {@link Iterable}
	 * 
	 * @param <T>
	 * @param enumeration
	 * @return empty list, if the enumeration is null, else return an iterable that
	 *         is used to traverse the elements of enumeraiton.
	 */

	public static <T> Iterable<T> toIterable(final Enumeration<T> enumeration) {
		if (enumeration == null) {
			return Collections.emptyList();
		}

		final Iterable<T> iterable = () -> new Iterator<T>() {
			@Override
			public boolean hasNext() {
				return enumeration.hasMoreElements();
			}

			@Override
			public T next() {
				return enumeration.nextElement();
			}
		};

		return iterable;
	}

	public static void main(String[] args) {
		final Vector<Integer> primesVector = new Vector<>();
		primesVector.addAll(Arrays.asList(2, 3, 5, 7, 11));

		final Enumeration<Integer> primesEnumeration = primesVector.elements();
		Iterable<Integer> iterable = toIterable(primesEnumeration);

		for (int i : iterable) {
			System.out.println(i);
		}
	}
}

 

Output

2
3
5
7
11

  

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