panda.io.resource.ResourceEnumeration Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of panda-core Show documentation

Panda Core is the core module of Panda Framework, it contains commonly used utility classes similar to apache-commons.

There is a newer version: 1.8.0

package panda.io.resource;

import java.util.Enumeration;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;

/**
 * Implements an Enumeration that combines elements from a Set and an Enumeration.
 */
public class ResourceEnumeration implements Enumeration {

	Set set;
	Iterator iterator;
	Enumeration enumeration; // may remain null

	/**
	 * Constructs a resource bundle enumeration.
	 * @param set an set providing some elements of the enumeration
	 * @param enumeration an enumeration providing more elements of the enumeration.
	 *        enumeration may be null.
	 */
	ResourceEnumeration(Set set, Enumeration enumeration) {
		this.set = set;
		this.iterator = set.iterator();
		this.enumeration = enumeration;
	}

	String next = null;

	/**
	 * @see java.util.Enumeration#hasMoreElements()
	 */
	public boolean hasMoreElements() {
		if (next == null) {
			if (iterator.hasNext()) {
				next = iterator.next();
			}
			else if (enumeration != null) {
				while (next == null && enumeration.hasMoreElements()) {
					next = enumeration.nextElement();
					if (set.contains(next)) {
						next = null;
					}
				}
			}
		}
		return next != null;
	}

	/**
	 * @see java.util.Enumeration#nextElement()
	 */
	public String nextElement() {
		if (hasMoreElements()) {
			String result = next;
			next = null;
			return result;
		} else {
			throw new NoSuchElementException();
		}
	}
}