用java泛型实现循环链​​表

Question

我正在学习 java，我还是个初学者。我编写了这段代码来实现一个循环链表，当我尝试打印列表时，它会不断打印数字。它看起来像是某种无限循环。我什至尝试使用调试，但它对我没有多大作用。如果您可以查看代码并了解发生这种情况的原因，我将非常感激。这是下面的代码。我也会给我关于代码的反馈:) 这是循环链表的类

public class CircularLinkedList<E> implements API<E> {
    private Node<E> head;
    private int size = 0;

    public void placeAtBeginning(E element) {
        Node<E> newNode = new Node<E>(element);
        if(head == null) {
            head = newNode;
            head.setNext(head);
        }else {
            Node<E> temp = head;
            head = newNode;
            newNode.setNext(temp);
        }
        size++;
    }

    public void placeAtEnd(E element) {
        Node<E> newNode = new Node<E>(element);
        if (head == null) {
            head = newNode;
        }else {
            Node<E> temp = head;
            while (temp.getNext() != head) {
                temp = temp.getNext();
            }
            temp.setNext(newNode);
        }

        newNode.setNext(head);
        size++;
    }

    public void deleteFromBeginning() {
        Node<E> temp = head;
        while (temp.getNext() != head) {
            temp = temp.getNext();
        }
        temp.setNext(head.getNext());
        head = head.getNext();
        size --;
    }

    public void deleteFromEnd() {
        Node<E> temp = head;
        while(temp.getNext().getNext() != head) {
            temp = temp.getNext();
        }
        temp.setNext(head);
        size--;
    }

    public void print() {
        Node<E> temp = head;
        while(temp.getNext()!= head) {
            System.out.print(temp.getValue() + " , ");
            temp = temp.getNext();
        }
        System.out.print(temp.getValue());
    }
}

这是我的节点的类

public class Node<T> {
    private Node<T> next;
    private T item;

    public Node(T item) {
        this.item = item;
    }

    public void setNext(Node<T> next) {
        this.next = next;
    }

    public Node<T> getNext() {
        return this.next;
    }

    public T getValue() {
        return this.item;
    }
}

这是我尝试使用 int 测试它的主要部分。

public class Main {
    public static void main(String [] args) {
        API <Integer> list = new CircularLinkedList<Integer>();

        int a = 10;
        int b = 3;
        int c = 15;
        int d = 8;
        int f = 9;

        list.placeAtBeginning(a);
        list.placeAtEnd(b);
        list.print();
        System.out.println();
        list.placeAtBeginning(c);
        list.placeAtBeginning(d);
        list.print();
    }
}

这是我使用的 API

public interface API <E> {
    public void placeAtBeginning(E element);
    public void placeAtEnd(E element);
    public void deleteFromBeginning();
    public void deleteFromEnd();
    public void print();
}

Answer 1

您的方法placeAtBeginning() 不会在循环列表中插入新元素，而只是让新元素的next 引用原始循环列表。

试试这个：

public void placeAtBeginning(E element)
{
  Node<E> newNode = new Node<E>(element);
  if(head == null)
  {
    head = newNode;
    head.setNext(head);
  }
  else
  {
    Node<E> last = head;
    while (last.getNext() != head)
      last = last.getNext();
    newNode.setNext(head);
    head = newNode;
    last.setNext(head);
  }
  size++;
}

我没有检查其他方法。它们可能包含类似的错误。