MultiSet - Enable assertions.

I have a class for my MultiSet<E>, and an associated test-program.

My class is a follows:

Code :

public class MultiSet<E> extends AbstractCollection<E>
{
	private int size = 0;
	private Map<E, Integer> values = new HashMap<E, Integer>();
 
	public MultiSet()
	{
 
	}
 
	public MultiSet(Collection<E> c)
	{
		addAll(c);
	}
 
	@Override
	public boolean add(E e)
	{
		Integer i = values.get(e);
		if (i == null)
			values.put(e, 1);
		else
			values.put(e, i + 1);
		return true;
	}
 
	@Override
	public boolean remove(Object o)
	{
		Integer i = values.remove(o);
		return i != null;
	}
 
	public Iterator<E> iterator()
	{
		return new Iterator<E>()
		{
			private Iterator<E> iterator = values.keySet().iterator();
			private int remaining = 0;
			private E current = null;
 
			public boolean hasNext()
			{
				return remaining > 0 || iterator.hasNext();
			}
 
			public E next()
			{
				if (remaining == 0)
				{
					current = iterator.next();
					remaining = values.get(current);
				}
				remaining--;
				return current;
			}
			public void remove()
			{
				throw new UnsupportedOperationException();
			}
		};
	}
		@Override
		public boolean equals(Object object)
		{
 
			if (this == object) return true;
			if (object == null) return false;
			if (this.getClass() != object.getClass()) return false;
			MultiSet<?> o = (MultiSet<?>) object;
			return o.values.equals(values);
		}
 
		@Override
		public int hashCode()
		{
			return values.hashCode()*163 + new Integer(size).hashCode()*389;
		}
 
		@Override
		public String toString()
		{
			String res = "";
			for (E e : values.keySet())
			{
					res = res + "[" + e.toString() + ":" + values.get(e) + "]";
			}
			return getClass().getName() + res;
		}
 
		public int size()
		{
			return values.size();
		}
	}

And the test program:

Code :

public class MultiSetTest {
 
    public static void main(String[] args) {
	MultiSet<String> a = new MultiSet<String>();
	MultiSet<String> b = new MultiSet<String>();
 
	a.add("Foo");
	a.add("Bar");
	a.add("Foo");
	System.out.println("a:" + a); // test toString
 
	b.add("Bar");
	b.add("Foo");
	b.add("Bar");
	b.add("Foo");
	System.out.println("b:" + b);
 
	assert !a.equals(b) : "Failed test 1!"; // test equals
	assert b.remove("Bar") : "Failed test 2!"; // test remove
	assert a.equals(b) : "Failed test 3!";
	for(String s : a) { // test iterator
	    assert b.remove(s) : "Failed test 4!";
	}
	assert b.size() == 0 : "Failed test 5!";
 
	Set<String> baseSet = new HashSet<String>(a);
	assert baseSet.size()==2 : "Failed test 6!";  
 
	b = new MultiSet<String>(a);
	assert a.equals(b) : "Failed test 7!";
 
	try {
	    assert false;
	    System.out.println("Please enable assertions!");
	}
	catch(AssertionError e) {
	    System.out.println("Success!");
	}
    }
}

To me it seems to be working, but if my MultiSet-class was working proberly, then the output should be: "Success!"

Instead i get: "Please enable assertions!".

Where/how do i enable assertions?