package examples;

import java.util.*;

/**
 * CS401 Example 28
 * 
 * 
 * 
 * @author PJ Dillon
 */
public class ex28
{
	public static void main(String[] args)
	{
		String[] strs = {"transaction", "seriptitious", "sharpener", "Baseball", 
				"perspecacity", "constellation", "Marzipan", "negociation"};
		
		/* 
		 * Experiment with this changing the types of collection used. With 
		 * polymorphism, any collection can we used here and the rest of the code 
		 * will work.
		 */
		Collection collection = new HashSet();
		
		/*
		 * The foreach loop works for arrays too, as shown in comments here. The 
		 * traditional style for loop is used to explicitly show the order in which
		 * the strings are added to the Collection.
		 */
		//for(String str : strs)
		//	collection.add(str);
		for(int i = 0; i < strs.length; i++)
		{
			System.out.println(strs[i]);
			collection.add(strs[i]);
		}
		System.out.println();
		
		printCollection(collection);
	}
	
	public static void printCollection(Collection collection)
	{
		/*
		 * The two styles of iteration are shown below. The first explicitly
		 * declares an Iterator object and assigns it to the Collection objects
		 * returned iterator. The Collection interface defines this methods,
		 * requiring that all Collections provide some sort of Iterator. The method
		 * returns an iterator that can iterate over the items in the current
		 * Collection.
		 * 
		 * The second style shows the use of the new foreach loop to iterate over
		 * each string in the collection without requiring use to declare a separate
		 * iterator object.
		 * 
		 * A Collection, in general, and particularly a hashSet implement no
		 * concept of an order to the elements that it stores; conversely, an array
		 * imposes a known ordering based upon the indexing of its elements. Notice
		 * in the output, then, that this will print the strings in a different
		 * order than that in which they were added. The Iterator, though, for both
		 * of the loops shown traverses the Collection in a consistent manner. This
		 * is not guaranteed for the Collection, though, especially as the HashSet
		 * needs to resize itself. 
		 */
		for(Iterator i = collection.iterator(); i.hasNext(); 
			System.out.println(i.next()));
		
		System.out.println();
		
		/*
		 * In order to be as generic as possible, a collection returns references
		 * to the Object class, which is the superclass of any java object. Thus,
		 * a collection can store any java object. This requires us to cast the
		 * object to an instance of whatever type we need. Here, though, we're using
		 * the toString() method of the object; so no cast is necessary.
		 */
		for(Object o : collection)
			System.out.println(o);
	}
}