1、实现功能

1）add()：链表末尾添加元素；
2）pop()：移除链表尾部元素；
3）insert()：指定索引处添加元素；
4）delete()：指定索引处删除元素；
5）getSize()：获取链表当前长度；
6）display()：展示链表当前元素。

2、代码

package DataStructure;

/**
 * @author: Inki
 * @email: inki.yinji@qq.com
 * @create: 2020 1024
 * @last_modify: 2020 1025
 */

public class MySingleLinkedList  {

 /**
  * Only used to store the head node.
  */
 private SingleNode head = new SingleNode(new Object());

 /**
  * The single linked list current size.
  */
 private int size = 0;

 /**
  * Add element to the end of the list.
  * @param:
  *  paraVal: The given value.
  */
 public void add(AnyType paraVal) {
  insert(size, paraVal);
 }//Of add

 /**
  * Pop the last element.
  * @return:
  *  The popped value.
  */
 public AnyType pop(){
  return delete(size - 1);
 }//Of pop

 /**
  * Insert element at specified index.
  * @param:
  *  paraIdx: The given index.
  *  paraVal: The given value.
  */
 public void insert(int paraIdx, AnyType paraVal) {

  if (paraIdx > size) {
   throw new IndexOutOfBoundsException("The index error.");
  }//Of if

  SingleNode  tempNode = head;
  int i = 0;
  while (i++ < paraIdx) {
   tempNode = tempNode.next;
  }//Of while

  SingleNode paraNode = new SingleNode <>(paraVal);
  paraNode.next = tempNode.next;
  tempNode.next = paraNode;
  size++;
 }//of add

 /**
  * Delete the element at specified index.
  * @param:
  *  paraIdx: The given index of element to delete.
  * @return:
  *  The deleted value.
  */
 public AnyType delete(int paraIdx) {
  if (size == 0) {
   throw new RuntimeException("The single linked list is empty.");
  }//Of if

  if (size <= paraIdx) {
   throw new IndexOutOfBoundsException("The index error.");
  }//Of if

  SingleNode  retNode = head;
  int i = 0;
  while (i++ < paraIdx) {
   retNode = retNode.next;
  }//Of while

  retNode.next = retNode.next.next;

  size--;
  return retNode.val;
 }//Of delete

 /**
  * Get the current size of the single linked list.
  * @return:
  *  The current size of the single linked list.
  */
 public int getSize() {
  return size;
 }//Of getSize

 /**
  * Display the single linked list.
  */
 public void display() {
  if (size == 0) {
  throw new RuntimeException("The single linked list is empty.");
  }//Of if
  
  System.out.print("The single linked list is:\n[");
  SingleNode  tempNode = head;
  int i = 0;
  while (i++ < size - 1) {
   tempNode = tempNode.next;
   System.out.printf("%s, ", tempNode.val);
  }//Of while
  System.out.printf("%s]\n", tempNode.next.val);
 }//Of display

 /**
  * The main function.
  */
 public static void main(String[] args) {
  MySingleLinkedList  test = new MySingleLinkedList<>();
  test.add('a');
  test.add('b');
  test.insert(0, 'c');
  test.add('d');
  test.insert(0, '5');
  test.delete(4);
  test.pop();
  test.add('+');
  test.display();
  System.out.println(test.getSize());
 }//Of main

}//Of class MySingleLinkedList

class SingleNode {

 /**
  * The value.
  */
 AnyType val;

 /**
  * The next node.
  */
 SingleNode next;

 /**
  * The first constructor.
  * @param
  *  paraVal: The given value.
  */
 SingleNode (AnyType paraVal) {
  val = paraVal;
 }//The first constructor

}//Of class SingleNode