LinkedList implementation with Iterators in Java
Use (at least parts of) the source, Luke

You mentioned that you decided to implement iterators on your own, but you could at least use the standard Iterator interface. It's almost the same as what you did, having only two methods, hasNext, and next. Not only it's standard so that it should be familiar to all readers, those are better names too, and follow the camelCase convention of the language.

What's in a name?

Using a common vocabulary helps programmers understand each other's code. It's OK to implement a common library class on your own for practice, but to facilitate communication, it's good to stick to the common vocabulary. So in the future I suggest to use the same names for methods used by the JDK, unless there is a good reason to deviate.

Inner classes

When possible, it's good to make inner classes static, so that instances of those classes don't hold a reference to the enclosing class. You could make ListIterator static by passing mBase to its constructor.

Performance

The getSize method had \$O(n)\$ time complexity, because it iterates over the elements every time it's called. (Btw, it's a bit ironic that the implementation doesn't use the iterator, what a missed opportunity!) You could do better, at the expense of an integer field, incremented when you add a new item, decremented when you remove an item. The there time complexity would become \$O(1)\$.

Simplify

This can be written simpler:


   boolean isNext(){
        if (next == null) return (false);
        return (true);
    }



Like this:

   boolean isNext() {
        return next != null;
    }