包装类的 LinkedList 迭代器实现

Question

So I implemented the following LinkedList wrapper class:

import java.util.LinkedList;
import java.util.ListIterator;

public class LinkedListWrapper {

    private LinkedList<String> listWrapper;

    public LinkedListWrapper(){
        this.listWrapper = new LinkedList<String>();
    }

    /**
     * Method to check if the linked list contains the string object.
     * @param str String object to check if the list contains.
     * @return True if the list contains it and false otherwise.
     */

    public boolean contains(String str){
        return this.listWrapper.contains(str);
    }

    /**
     * Method to add a String object to the list.
     * @param str String object to add.
     * @return True if the item was added and false otherwise.
     */

    public boolean add(String str){
        if(!this.contains(str)){
            this.listWrapper.add(str);
        }
        return false;
    }


    /**
     * Method to delete str object
     * @param str String object to delete
     * @return True if str was deleted and false otherwise.
     */

    public boolean delete(String str){
        return this.listWrapper.remove(str);
    }

}

However, Now that I create an array of LinkedListWrapper and I want to iterate through the linked list's strings, I obviously can't - because I haven't implemented an iterator. I searched the LinkedList API But I didn't quite get how to implement the Iterator properly.

Answer 1

You need to implement the Interable<> interface and override its methods :

    class LinkedListWrappe implements Iterable<> { 

    // code for data structure 
    public Iterator<> iterator() { 
        return new CustomIterator<>(this); 
    } 
} 
class CustomIterator<> implements Iterator<> { 

    // constructor 
    CustomIterator<>(CustomDataStructure obj) { 
        // initialize cursor 
    } 

    // Checks if the next element exists 
    public boolean hasNext() { 
    } 

    // moves the cursor/iterator to next element 
    public T next() { 
    } 

    // Used to remove an element. Implement only if needed 
    public void remove() { 
        // Default throws UnsupportedOperationException. 
    } 
} 

Code example is more or less taken from here .