使用带有堆栈的链表:节点中的私有访问错误

Question

我一直在获取x，然后在Node中有一个私有访问。我试着玩，并不断得到相同的错误，无论我在我的节点类和我的链表类切换。我有我的节点保存在一个不同的文件，它看起来像这样:"

public class Node{
	private Node next;
	private String name;
	private int ssn;
	private int key;
	public Node(String name, int ssn){
		this.name = name;
		this.ssn = ssn;
	}
	public void setNext(Node n){
		this.next = next;
	}
	public int getSSN(){
		return this.ssn;
	}
	
	public int getKey(){
		return ssn%10000;
	}
	public String getName(){
		return name;
	}
	
	public Node getNext(){
		return this.next;
	}
	public void setSSN(int ssn){
		this.ssn= ssn;
	}

然后是我的链表堆栈代码就像这样:

public class StackLL{
	private Node head; //Whatever is on top of the stack
	private int n; //Suze of the stack
	private Node next;
	
	public StackLL(){
		head = null;
		n = 0;
	}
	
	public boolean isEmpty(){
		return n == 0;
	}
		
	public void push(){
		Node temp = head;
		head = new Node();
		head.x = x;
		Node head.next = temp;
		n++;
	}
	
	public Node pop(){
		Node x = head.x;
		head = head.next;
		n--;
		return x;
	}
		
	public Node top(){
		return head.x;
	}
	
	// printStack method for StackLL
	public void printStack() {
		System.out.println(n);
		Node temp = head;
		while (temp != null) {
		System.out.println(temp.getKey());
		temp = temp.getNext();
        }
    }
	
}

Answer 1

我在你的代码中插入了关于我看到的问题的注释。在Node类中只有一个，在setNext()中:

public void setNext(Node n){
    // assign the parameter to the field
    this.next = n;
}

有一个数字在StackLL类:

public class StackLL{
    private Node head; //Whatever is on top of the stack
    private int n; //Suze of the stack
    // the field next is not used; just delete it
//  private Node next;
    public StackLL(){
        head = null;
        n = 0;
    }
    public boolean isEmpty(){
        return n == 0;
    }
    public void push(){
        Node temp = head;
        // The Node constructor takes two arguments
        head = new Node("Jim", 541365250);
        // x is not defined; delete this statement
//      head.x = x;
        // Node.next is not visible (it’s private), so use the setter 
        head.setNext(temp);
        n++;
    }
    public Node pop(){
        // if you want to return a Node, just return head
        Node x = head;
        // next is private, use the getter
        head = head.getNext();
        n--;
        return x;
    }
    public Node top(){
        // if you want to return a Node, just return head
        return head;
    }
    // printStack method for StackLL
    public void printStack() {
        System.out.println(n);
        Node temp = head;
        while (temp != null) {
        System.out.println(temp.getKey());
        temp = temp.getNext();
        }
    }
}

除了pop()中的局部变量外，我没有发现x，所以我删除或更改了对它的引用。返回仍然链接到其他节点的Node实例在生产代码中不是一个好主意，但我现在让它成为。