CODEWITHSUNDEEP
javainterface
Rio
Rio

Reputation: 13

can not find method from my interface

I created an interface called LLIterator that extends iterator and add two methods to it, when i tried to use it in one of my class, I couldn't compile it. Here is what I got. my custom interface is like this:

      import java.util.Iterator;

        public interface LLIterator<T> extends Iterator<T>{

        boolean hasNext();

        T next();

        void remove();

        void addBefore(T element);

        void addAfter(T element);

        }

my linkedlist is like this:

import java.lang.StringBuilder;
import java.util.NoSuchElementException;
import java.util.Iterator;
import java.util.ArrayList;


/**
 * A class to represent a linked list of nodes.
 */
public class LinkedList<T> implements Iterable<T>{
  /** the first node of the list, or null if the list is empty */
  private LLNode<T> first;

 /** some codes here  

 @Override
  public LLIterator<T> iterator() {
    return new LinkedListIterator();
  }

  private class LinkedListIterator implements LLIterator<T>{
    LLNode<T> nodeptr = first;
    final LinkedList<T> list = getList();

   @Override
    public void addBefore(T element){
      if(nodeptr == first || list.isEmpty()){
        throw new NoSuchElementException();
      }
      LLNode<T> newnode = new LLNode<T>(element, null);
      newnode.setNext(nodeptr);
    }

    @Override
    public void addAfter(T element){
      LLNode<T> newnode;
      if(nodeptr == first || list.isEmpty()){
        newnode = new LLNode<T>(element, null);
        list.setFirst(newnode);
      }
      newnode = new LLNode<T>(element, null);
      newnode.setNext(nodeptr.getNext());
      nodeptr.setNext(newnode);
    }
  }

in another class, i used iterator method of the this Linkedlist and called addBefore method, however when I compile it, it shows

cannot find symbol
  symbol:   method addAfter(WordData)
  location: variable iterator of type java.util.Iterator<WordData>

here is part of my another class:

 public void addFollowingWord(String word){
    Iterator<WordData> iterator = list.iterator();
    WordData current = iterator.next();
    while(iterator.hasNext()){
      if(current.getWord().equals(word)){
        current.incrementCount();
      }
      else if(current.getWord().compareTo(word) < 0){
        current = iterator.next();
      }
      else if(current.getWord().compareTo(word) > 0){
        WordData newword = new WordData(word);
        iterator.addBefore(newword);
      }
    }
    if(!iterator.hasNext()){
     WordData newword = new WordData(word);
      iterator.addAfter(newword);
  }
}

I'm very confused, did I make any mistake somewhere or I missed something?

Upvotes: 0

Views: 107

Answers (1)

shmosel
shmosel

Reputation: 50716

You can't access the methods on the custom interface because it's cast as Iterator. Update your iterator() method to return your subinterface:

@Override
public LLIterator<T> iterator() {
    return new LinkedListIterator();
}

Upvotes: 4

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