public class Singlelinkedlist<AnyType> {
    
    class Node<AnyType> {
        public  AnyType data;
        public  Node<AnyType> next;
        public Node(AnyType data,Node<AnyType> next){
            this.data=data;
            this.next=next;
        }
    }
    //首元节点
    private Node<AnyType> first; //指向链表中第一个元素所在的结点

    //头指针
    private Node<AnyType> head; //指向头节点

    //链表长度
    int thesize;

    //初始化链表
    public boolean initlist(){
        thesize=0;
        first=new Node<>(null,null);
        head=new Node<>(null,first);
        return true;
    }

    //判断链表是否为空
    public boolean isEmpty(){
        return thesize==0;
    }

    //获取节点
    public Node<AnyType> getNode(int i){
        Node<AnyType> renode=head;
        for(int j=0;j<i;j++){
            renode=renode.next;
        }
        return renode;
    }
    //在头部添加元素
    public void addFirst(AnyType a){
        Node<AnyType> renode=new Node<>(a,null);
        
        renode.next = first;
  
        first = renode;
        head.next  = first;
        
        thesize++;
    }



   
    //打印链表
    public void print(){
        for(int i=1;i<thesize;i++){
            System.out.print(getNode(i).data+"--");       
        }
        System.out.println(getNode(thesize).data);
    }
    public static void main(String[] args) {
        Singlelinkedlist<Integer> l = new Singlelinkedlist();
        l.initlist();

        for(int i =0;i<3;i++){
            l.addFirst(i+1);
        }
        l.print();
      //  Outter.Inner inner = outter.new Inner();

        Singlelinkedlist<Integer>.Node<Integer> fir= l.new Node<>(null,null);//调用内部类，必须铜鼓Singlelinkedlist对象来实现         fir = l.first;         System.out.println(fir.data);                 }  
}

3--2--1
3

调用内部类还有其他方法 https://baijiahao.baidu.com/s?id=1705524150855334181&wfr=spider&for=pc