what's up with HashSet?

[Randall Twede]

i don't see any get methods at all!!!
i guess you use the iterator() method.
i never learned using iterators. could someone show me how? here is the offending code(you might notice i am more used to using arrays):

		HashSet<Integer> products = new HashSet<Integer>();
		int product = 0;
		int answer = 0;

		for(int i = 0; i < products.size(); i++)
		{
			answer = answer + products(i);
		}
		return Integer.toString(answer);

i am just trying to get the sum of all the ints in the HashSet

[Pete Nelson]

A HashSet is a specific implementation of java.util.Set that is backed by a HashMap. Note that it doesn't implement java.util.Map (it "has a" Map, not "is a" Map). Strait from the javadoc, a Set "makes no guarantees as to the iteration order of the set", which is why trying to retrieve an object at a particular index will not work.

Is a Set truly what you are looking for here? Sets do not allow duplicates, so you would only get the sum of UNIQUE integers if you are using a Set.

[Randall Twede]

yes, no duplicates is why i chose it. i found an article that not only shows how to use iterators, but also the for-each statement. that should make it very easy.

		for(Integer i : products)
		{
			answer = answer + i.intValue();
		}

if you ask me the java language is improving
i still have problems with this problem but the HashSet is not one now

[Jeff Verdegan]

Note that you should always use a foreach loop or an explicit Iterator to iterate any collection. Never use get(i).

i never learned using iterators. could someone show me how?

java iterator tutorial
http://docs.oracle.com/javase/tutorial/collections/index.html

[Xavier Figueroa]

You need something like:

        Iterator<Integer> it = products.iterator();

        while (it.hasNext()) {
            answer = answer + it.next();
        }
...

}

or use an enhanced for loop

[Jesper de Jong]

With the new for-loop syntax you don't need to use an Iterator explicitly. You can also make use of auto(un)boxing, which means you don't need to call intValue() on the Integer object. You could write it like this:

Set<Integer> products = new HashSet<Integer>();

// ...

int answer = 0;
for (int i : products) {
    answer += i;
}