双链列表中的hasPrevious（）方法

Question

For class I am creating a doubly linked list with an iterator. We have just started this sort of stuff, so my experience with it is only a few weeks old.

When creating a method to check if a doubly linked list in Java has an element in the previous position behind a cursor, is it proper to use the following code?

 public boolean hasPrevious() {
    if(cursor.prev != null){return true; }
    return false;

I am wondering because my professor told me to rethink that method, but I can't really think of where else to go with it. Is there anything certain he may be looking for pertaining to iterators or doubly linked lists that I'm missing?

edit: Yes, my cursor is part of the iteration. It is supposed to be between two elements in the code.

Answer 1

Maybe he wanted you to simplify it a little bit

public boolean hasPrevious() {
   if (cursor != null)
      return curser.prev != null;
   return false;
}

Answer 2

The method could be simplified:

public boolean hasPrevious() {
   return cursor != null && cursor.prev != null;
}

Answer 3

I believe this is the most simplified way

public boolean hasPrevious() {
    return (current.previous != null);
}

public E previous() {
    if (hasPrevious()) {
        E result = current.element;
        current = current.previous;
        return result;
    }
    throw new NoSuchElementException();
}

Answer 4

如果您在这里提到的是正确的，那么答案是肯定的。