我有一个linkedlistdouble类 public ListIterator<T>listIterator() 方法，我正在尝试执行接口listiterator，因为它是匿名内部类，我走的是正确的路径吗？我应该怎么做才能使 public int nextIndex() / public int previousIndex() 工作？nextindex方法返回后续调用next将返回的元素的索引，如果列表迭代器位于列表的末尾，并且previousindex方法返回后续调用previous将返回的元素的索引，则返回list size，或者-1，如果列表迭代器如这里所说位于列表的开头
这是linkedlistdouble类

public class LinkedListDouble <T>  {
 private Node first = null;
 private Node last = null;

 public LinkedListDouble ()         // constructor
 {
    first = null;                  // no items on list yet
    last = null;

 }

 public void add(T item) {
     Node newNode = new Node(item);
        if (isEmpty()) {
            first =newNode;
            last = newNode;

        }  
        else {
            //first.setPrev(newNode); 
            //newNode.setNext(first); 
            //first = newNode;

            last.setNext(newNode);
            newNode.setPrev(last);
            last=newNode;
        }
    }
    public boolean contains(T item){
        if(first==null)
            return false;
        else
        {
            Node newNode=first;
            while(newNode!=null)
            {
                if(newNode.getInfo().equals(item))
                    return true;
                else
                    newNode=newNode.getNext();
            }
        }
        return false; 
 }

   public T remove(T item)
    {//get care of first and last nodes
       //and if there is more than 1 matching
        boolean check=contains(item);
        if(check==true)

        {
            Node newNode=first;
            while(newNode!=null)
            {
                if(newNode.getInfo().equals(item))
                {
                    newNode.getPrev().setNext(newNode.getNext());
                    newNode.getNext().setPrev(newNode.getPrev());
                    return item;
                }
                else
                    newNode=newNode.getNext();
            }

        }
        return null;

    }

   public int size()
   {
       int size=0;
       if(first==null)
           return size;
       else
       {

        Node newNode=first;
        while(newNode!=null)
        {
            size++;
            newNode=newNode.getNext();

        }

       }
       return size;
   }

   public String toString()
   {
    Node newNode=first;
    String s="";
    while(newNode!=null)
    {
        s+=newNode.getInfo()+" ,";
        newNode=newNode.getNext();
    }
    return s;

   }

 public boolean isEmpty() {
        return first == null;
    }

下面是应该执行接口listiterator的方法，因为它是匿名的内部类，我到目前为止尝试了：

public ListIterator<T>listIterator() 
 {
     ListIterator<T>listIterator = new ListIterator<T>() {
     private Node current = first;
     private Node temp2 = null;
     private int curindex = 0;

    @Override
    public void add(T e) {
        // TODO Auto-generated method stub
        throw new RuntimeException();
    }

    @Override
    public boolean hasNext() {
        // TODO Auto-generated method stub
        boolean flag=true;
        if(current.getNext()==null)
        {
            flag=false;
        }
        return flag;
    }

    @Override
    public boolean hasPrevious() {
        // TODO Auto-generated method stub
        boolean flag=true;
        if(current.getPrev()==null)
        {
            flag=false;
        }
        return flag;
    }

    @Override
    public T next() {
        // TODO Auto-generated method stub
         if (!hasNext()) throw new NoSuchElementException();

         temp2=current.getNext();
          current=current.getNext();
          return (T) temp2.getInfo();

    }

    @Override
    public int nextIndex() {
        // TODO Auto-generated method stub
        int counter=0;
        if(!hasNext()) return size();
        return curindex;

    }

    @Override
    public T previous() {
        // TODO Auto-generated method stub
         if (!hasPrevious()) throw new NoSuchElementException();

         temp2 = current.getPrev();
         temp2 = temp2.getPrev();

          return (T) temp2.getInfo();
    }

    @Override
    public int previousIndex() {
        // TODO Auto-generated method stub
        int counter=0;
        if(!hasPrevious()) return -1;
        return curindex-1;
    }

    @Override
    public void remove() {
        // TODO Auto-generated method stub
        throw new RuntimeException();
    }

    @Override
    public void set(T e) {
        // TODO Auto-generated method stub
        throw new RuntimeException();
    } 

     };
     return listIterator;
 }