java - 我删除具有 X 年龄值的特定节点的删除方法将不起作用

Question

这是我的代码，请仅引用主要方法和删除方法，其他方法只是为了显示完整的程序。我听说Java将方法参数作为按值传递，这就是问题所在，并且对象的属性是按引用传递。

所以基本上我可以更改Node.age，因为age是一个属性，但我不能使Node等于Node = Node.next？我已经从事这个工作有一段时间了，只是想学习如何进行不同的操作，并且一直停留在这个问题上。 if 语句执行完毕，但是 headNode 并不像我希望的那样等同于 headNode.next:

public class Node {
    int age;
    Node next;
    Node previous;

    public static void main (String [] args) {
        Node firstNode = new Node(18);
        Node t = firstNode;

        Node randomFatNode = new Node();

        for(int i = 0; i < 30; i += 3) {
            Node tempNode = new Node(i + 21);
            firstNode.next = tempNode;
            tempNode.previous = firstNode;
            firstNode = tempNode;
        }

        Node tailNode = firstNode;

        firstNode = t;

        traverseForward(firstNode);
        //Prints out: Traversal Forward -> 18 -> 21 -> 24 -> 27 -> 30 -> 33 -> 36 -> 39 -> 42 -> 45 -> 48 -> null


        deleteNode(firstNode, 18); //Does not delete the first node, which has the age of 18.

        traverseForward(firstNode);
        //Prints out: Traversal Forward -> 18 -> 21 -> 24 -> 27 -> 30 -> 33 -> 36 -> 39 -> 42 -> 45 -> 48 -> null
    }

    public Node() {
        this.age = 20;
        this.next = null;
        this.previous = null;
    }

    public Node(int inputAge) {
        this.age = inputAge;
        this.next = null;
        this.previous = null;
    }

    public static void traverseForward(Node headNode) {
        System.out.print("Traversal Forward -> ");
        Node useThisForTestNode = headNode;
        while(useThisForTestNode != null) {
            System.out.print(useThisForTestNode.age + " -> ");
            useThisForTestNode = useThisForTestNode.next;
        }
        System.out.print("null ");
        System.out.println();
    }

    public static void deleteNode(Node headNode, int keyToDelete) {
        Node temp = headNode;
        if(temp != null && temp.age == keyToDelete)  {
            headNode = headNode.next;
            System.out.println("TEST");
            //Printed out TEST to see if if statement went through. It did, but the node in the linked list remained unchanged.
        }
    }

    // Other methods
}

Answer 1

您需要将firstNode作为类字段。