原理：链表功能强大,可在头或尾进行插入和删除。

public class ListToStack {
      LinkedList
    
      linkedList = new LinkedList<>();     public void add(int value){
          linkedList.addLast(value);     }     public int remove(){
          return linkedList.removeFirst();     }     public int peek(){
          return linkedList.getFirst();     }     public boolean isEmpty(){
          return linkedList.isEmpty();     } } 总结：懂链表结构，so easy~