在范围内无法访问 OuterClass.StaticNestedClass 类型的封闭实例

Question

我仍在学习，目前正在尝试使用嵌套的 STATIC classes 实现 DoublyLinkedLists 并收到以下错误：

No enclosing instance of the type OuterClass.StaticNestedClass is accessible in scope 实际错误：
No enclosing instance of the type SolutionDLL.Node is accessible in scope

我有两个 STATIC 嵌套在 class 里面 class SolutionDLL class:

class SolutionDLL {
    public static class Node {
        private Object element;
        private Node   next;
        private Node   previous;

        Node(Object elementIn, Node nextNodeIn, Node prevNodeIn) {
            element = elementIn;
            next    = nextNodeIn;
            previous = prevNodeIn;
        }

        public Object getElement() {
            return element;
        }

        public Node getNext() {
            return next;
        }

        public Node getPrevious() {
            return previous;
        }

    }

    public static class DLList {
        public void addFirst(Node n) {
            SolutionDLL.Node tempNode = new SolutionDLL.Node(
                SolutionDLL.Node.this.getElement(),
                SolutionDLL.Node.this.getNext(), 
                SolutionDLL.Node.this.getPrevious()); 
            // do something
        }
    }
}

不管我这样调用:
SolutionDLL.Node.this.getElement()
像这样：
Node.this.getElement()

我仍然得到错误。我已经给出了框架代码，这是我第一次使用嵌套的 classes 来实现。因此，我们将不胜感激任何帮助。谢谢！

Answer 1

SolutionDLL.Node，就像任何 class 一样，没有 this 字段。 this 字段仅在对象内部可用，并且该对象的内部 classes class.

更改 addFirst 以获取来自 n 节点的值：

public static class DLList {
   private Node firstNode = null;

    public void addFirst(Node n) {

        //do something with the first node before it is assigned to the n
        if (firstNode != null){
            SolutionDLL.Node tempNode = new SolutionDLL.Node(
            firstNode.getElement(),
            firstNode.getNext(), 
            firstNode.getPrevious()); 
         }
         firstNode = n;
        // do something
    }
}

在范围内无法访问 OuterClass.StaticNestedClass 类型的封闭实例

No enclosing instance of the type OuterClass.StaticNestedClass is accessible in scope

java

class

inner-classes