Using an Iterator to filter an arbitrary Collection

[Jeff Cortez]

I'm a complete beginner with Java. Here's a question I have about the Oracle Java tutorial:

http://download.oracle.com/javase/tutorial/collections/interfaces/collection.html

The following method shows you how to use an Iterator to filter an arbitrary Collection, that is, traverse the collection removing specific elements.

static void filter(Collection<?> c) {
    for (Iterator<?> it = c.iterator(); it.hasNext(); )
        if (!cond(it.next()))
            it.remove();
}

I don't see how !cond creates a boolean expression for the if statement. If the collection holds references of type Boolean I understand that

    if (!(it.next()))

would remove, using the above snippet, any elements that are False.

Or if the collection holds Strings and you want to remove "cat" you could write

    if (it.next().equals("cat")

But what is the meaning of 'cond' in the tutorial? Is it an undefined condition? If so, the example in the tutorial seems to me unclear or a bug.

Thanks.

[Vijitha Kumara]

Welcome to CodeRanch, Jeff Cortez

Well, the code snippet is just a sample to show how it's done. The cond may represent a method which you could use to define a criteria/logic to be used for the objects of the Collection in order to be deleted...

[Rob Spoor]

It's basically a method, with a signature like this:

public boolean cond(Object object)

[Jeff Cortez]

Hi Vijitha and Rob. Thank you.

[Rob Spoor]

You're welcome