An example of a custom collection class that you can use to iterate over your own collection object using for_each loop. The key ingredient is Iterable, and Iterator interfaces implemented in CustomCollectionWrapper class.

CollectionTest.java

/**
 * 
 */

/**
 * Smart Cloud, Inc. Nov 14, 2013.
 * @author Alex Bush
 *
 */
public class CollectionTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		CustomCollectionWrapper collectionWrapper = new CustomCollectionWrapper();
		
		Object obj1 = new Object();
		Object obj2 = new Object();
		Object obj3 = new Object();
		
		System.out.println("obj1= " + obj1);
		System.out.println("obj2= " + obj2);
		System.out.println("obj3= " + obj3);
		
		collectionWrapper.add("one", obj1);
		collectionWrapper.add("two", obj2);
		collectionWrapper.add("three", obj3);
		
		System.out.println("\nIterating over our collection\n");
		
		for (String key : collectionWrapper) {
			Object obj = collectionWrapper.get(key);
			System.out.println("obj = " + obj + " for key: " + key);
		}
	}
}

CustomCollectionWrapper.java

import java.util.HashMap;
import java.util.Iterator;

/**
 * 
 */

/**
 * Smart Cloud, Inc. Nov 14, 2013.
 * @author Alex Bush
 *
 */
public class CustomCollectionWrapper implements Iterable<String>, Iterator<String> {
	private HashMap<String, Object> internalStorage = new HashMap<String, Object>();
	
	private int count = 0;

	public void add(String key, Object value) {
		internalStorage.put(key, value);
	}
	
	public Object get(String key) {
		return internalStorage.get(key);
	}
	
	@Override
	public boolean hasNext() {
		if (count <  internalStorage.size()) {
			return true;
	    }  
		return false;
	}

	@Override
	public String next() {
		if (count == internalStorage.size()) throw new IndexOutOfBoundsException();
		
		count++;
		
		return (String) internalStorage.keySet().toArray()[count - 1];
	}

	@Override
	public void remove() {
		throw new UnsupportedOperationException();
	}

	@Override
	public Iterator<String> iterator() {
		return this;
	}
}