/**
 * Java Collections Framework > HashSetExample.java
 *
 * Use a HashSet to store objects and retrieve them quickly.  HashSets are 
 * faster than TreeSets at retrieval but do not store their elements in 
 * sorted order.
 * @author  Feihong Hsu
 */

import java.util.HashSet;       // A container that supports quick retrieval
import java.util.Iterator;      // Useful for traversing a HashSet

public class HashSetExample {
    
    // This method prints the elements of a given HashSet object.
    public static void printHashSet(HashSet hashSet) {
        System.out.print( "HashSet: " );
        
        // Use an Iterator to print each element of the TreeSet.
        Iterator iterator = hashSet.iterator();
        while (iterator.hasNext())
            System.out.print( iterator.next() + ", " );
        System.out.println();
    }
    
    public static void main(String[] args) {
        HashSet hashSet = new HashSet();
        
        // Add 5 objects to the HashSet.
        hashSet.add("Viking");
        hashSet.add("Owari");
        hashSet.add("Ainu");
        hashSet.add("Incan");
        hashSet.add("Eskimo");
        
        // "HashSet: Incan, Ainu, Eskimo, Owari, Viking, "
        printHashSet(hashSet);        
        
        // Remove the element from the HashSet which is a String with 
        // value "Incan".
        hashSet.remove("Incan");
        
        // "HashSet: Ainu, Eskimo, Owari, Viking, "
        printHashSet(hashSet);
        
        // Find out if the hashSet contains a String with value "Incan".
        System.out.print( "HashSet contains Incan? " );
        System.out.println( hashSet.contains("Incan") );        // Prints false
        
        // Add another element to the HashSet.
        hashSet.add("Zulu");
        
        // "HashSet: Zulu, Ainu, Eskimo, Owari, Viking, "
        printHashSet(hashSet);
        
        hashSet.clear();        // Remove all elements from the HashSet
    }    
}