Question

我创建了一个双向链表并实现了我自己的迭代器。

然而，我做错了什么，我的迭代器导致无限循环。

一直在努力寻找错误，所以非常感谢任何反馈。提前致谢。我为代码墙道歉，我认为错误在于我创建Node类的方式的迭代器。

我的代码：

import java.util.Iterator;
import java.util.NoSuchElementException;

public class MyDoubleEndedLinkedList<T extends Comparable<T>> implements
Iterable<T> {
// initialising Nodes including the two sentinal nodes

private Node<T> head;
private Node<T> tail;
private Node<T> current;
private int currentsize;

MyDoubleEndedLinkedList() {
    head = new Node<T>();
    tail = new Node<T>();
    head.setNext(tail);
    tail.setPrevious(head);
    current = head;
    currentsize = 0;


// Methods used to help loop and iterate through the list
public boolean isEmpty() {
    return (current == head && current == tail);
}

public boolean endList() {
    return (current != tail);
}

public void resetCurrent() {
     current = head;
}

public void nextCurrent() {
    current = current.getNext();
}

public T getCurrent() {
    return current.getData();
}

public int size() {
    return this.currentsize;
}

   @Override
public Iterator<T> iterator() {

    return new LinkedListIterator<T>();
}

// Node class for doublyLinkedList

public class Node<E> {
    private Node<E> previous;
    private Node<E> next;
    private E data;

Node() {
    previous = null;
    next = null;
    data = null;
}

Node(Node<E> newPrevious, Node<E> newNext, E newData) {
    previous = newPrevious;
    next = newNext;
    data = newData;
}

// set previous node
public void setPrevious(Node<E> newPrevious) {
    previous = newPrevious;
}

// set Next node
public void setNext(Node<E> newNext) {
    next = newNext;
}

public void setData(E newData) {
    data = newData;
}

public Node<E> getPrevious() {
    return previous;
}

public Node<E> getNext() {
    return next;

}

public E getData() {
    return data;
}

}

class LinkedListIterator<E> implements Iterator<T> {
    private Node<T> current;
    private Node<T> previous;
    private Node<T> previous2;

    private boolean removeCalled;

    public LinkedListIterator() {
        current = head;
        previous = null;
        previous2 = null;
        removeCalled = false;
    }

    public boolean hasNext() {
        return (current != null);
    }

    public T next() {
        if (hasNext()) {

        T temp = current.getData();
        previous2 = previous;
        previous = current;
        current = current.next;
        removeCalled = false;
        return temp;
    }
    throw new NoSuchElementException();
}

    public void remove() {

        if (previous == null || removeCalled) {
        throw new IllegalStateException();
        }
        if (previous2 == null) {
        head = current;
        } else {
            previous2.setNext(current);
            previous = previous2;
        }
        removeCalled = true;

        throw new UnsupportedOperationException();
   }

}}

Answer 1

所以我找不到代码中的错误，但这里是Java中基本链表的简单实现。如果您向我展示如何向列表中添加元素，则可以更轻松地进行跟踪。

import java.util.Iterator;

public class MyLinkedList<T> implements Iterable<T> {
    private Node head = null;
    private Node tail = null;

    public static void main(String[] args) {
        MyLinkedList<String> li = new MyLinkedList<>();
        li.add("1");
        li.add("2");
        li.add("3");
        li.add("4");
        li.add("5");

        for (String s : li) {
            System.out.println(s);
        }
    }

    public void add(T data) {
        if (head == null) {
            head = new Node(data, null);
            tail = head;
        } else {
            Node n = new Node(data, tail);
            tail.next = n;
            tail = n;
        }
    }

    @Override
    public Iterator<T> iterator() {
        return new Iterator<T>() {

            Node current = head;

            @Override
            public boolean hasNext() {
                return current != null;
            }

            @Override
            public T next() {
                T data = current.data;
                current = current.next;
                return data;
            }

            @Override
            public void remove() {

            }
        };
    }

    class Node {
        final T data;
        Node prev = null;
        Node next = null;

        Node(T data, Node prev) {
            this.data = data;
            this.prev = prev;
        }
    }
}

使用Java的双链表上的无限迭代器循环

1 个答案: