Question

I’m currently working on a Doubly Linked List project in my college java course. I understand the concept of doubly linked lists, linked lists, and lists. However I’m having a lot of trouble writing my program as I’m not sure how to create the data I need to modify in my methods. Our professor usually gives us the input he will be using but didn’t this time, and I can’t seem to figure it out in my research.

I Suppose my main question is could anybody write some code for me to start working with and begin understanding what my methods need to be doing better?

Here is what I have so far. (Basically just the override skeleton..)

Thanks so much for any help.

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

public class DoublyLinkedList<E> implements List<E>{

DoublyLinkedListNode header;

public static void main(String[] args) {

}
public boolean add(E e) {
    return false;
}
public void add(int index, E element) {

}
public boolean addAll(Collection<? extends E> c) {
    return false;
}
public void clear() {
    header=null;
}
public boolean contains(Object o) {
    return false;
}
public E get(int index) {
    return null;
}
public int indexOf(Object o) {
    return 0;
}
public boolean isEmpty() {
    return header == null;
}
public int lastIndexOf(Object o) {
    return 0;
}
public ListIterator<E> listIterator() {
    return null;
}
public boolean remove(Object o) {
    return false;
}
public E remove(int index) {
    return null;
}
public int size() {
    return 0;
}
public Object[] toArray() {
    return null;
}
private class DoublyLinkedListNode{
    DoublyLinkedListNode next;
    DoublyLinkedListNode last;
    E contents;
}

//extra credit
private class DoublyLinkedListItr  implements java.util.ListIterator{

    public void add(Object arg0) {

    }
    public boolean hasNext() {

        return false;
    }
    public boolean hasPrevious() {

        return false;
    }
    public Object next() {

        return null;
    }
    public int nextIndex() {

        return 0;
    }
    public Object previous() {

        return null;
    }
    public int previousIndex() {

        return 0;
    }
    public void remove() {

    }
    public void set(Object arg0) {

    }

}
public ListIterator<E> listIterator(int index) {
    throw new UnsupportedOperationException("not implemented");
}
public <T> T[] toArray(T[] a) {
    throw new UnsupportedOperationException("not implemented");
}
public List<E> subList(int fromIndex, int toIndex) {
    throw new UnsupportedOperationException("not implemented");
}
public boolean retainAll(Collection<?> c) {
    throw new UnsupportedOperationException("not implemented");
}
public E set(int index, E element) {
    throw new UnsupportedOperationException("not implemented");
}
public boolean removeAll(Collection<?> c) {
    throw new UnsupportedOperationException("not implemented");
}
public boolean addAll(int index, Collection<? extends E> c) {
    throw new UnsupportedOperationException("not implemented");
}
public Iterator<E> iterator() {
    throw new UnsupportedOperationException("not implemented");
}
public boolean containsAll(Collection<?> c) {
    throw new UnsupportedOperationException("not implemented");
}

}

Answer 1

For creating the data here is the snippet:

public static void main(String[] args) {
  DoublyLinkedList<String> doublyLinkedList = new DoublyLinkedList<String>();
  doublyLinkedList.add("Hello");
  doublyLinkedList.add("World");
  // If you want to store int
  DoublyLinkedList<Integer> dlli = new DoublyLinkedList<Integer>();
  dlli.add(new Integer(10));
  dlli.add(new Integer(5));
}

I hope this is what you are looking for.