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Thread: MultiSet - Enable assertions.

  1. #1
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    Default MultiSet - Enable assertions.

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

    My class is a follows:

    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:

    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?


  2. #2
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    Default Re: MultiSet - Enable assertions.

    Google is your friend, learn to embrace it as you will get results far quicker than posting here.
    Use the forums when Google doesn't return anything relevant .

    Back on topic: To enable assertions all you need to do is add -ea to the command line arguments / program arguments before running your program.
    If you're running from the command line, usage is as such: java -ea TestHarness

    Or if you're using an IDE, such as eclipse, you will find the textfields for adding -ea in the area of run configurations.
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

  3. #3
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    Default Re: MultiSet - Enable assertions.

    args.jpg

    Is that correct?
    I wrote "-ea" at Program arguments for my Test-class,
    and when I run the program I still get the same fail-output :/

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    Default Re: MultiSet - Enable assertions.

    Apologies, should be under VM arguments in the IDE
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

  5. #5
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    Default Re: MultiSet - Enable assertions.

    Oh wait.
    It has to be VM arguments, ofcourse.

    Now; "Failed test 3!" xD
    So i guess there's a problem with my equals then :/

  6. #6
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    Default Re: MultiSet - Enable assertions.

    Do any of you see what the problem is?

  7. #7
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    Default Re: MultiSet - Enable assertions.

    well A is not equal to B, so it will fail
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

  8. #8
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    Default Re: MultiSet - Enable assertions.

    I found the problem.
    I modified my Add and remove-methods. No problems with the equals-method
    It works - the output is: Success.

    Success!!!
    And thank you for your help!

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