java队列的实现

队列也可以通过数组和链表两种方式来实现。

　1、链表方式实现

 class Node{
     Node next = null;
     int data;
     public Node(int data){this.data = data;}
 }

 public class MyQueue<E>{
     private Node<E> head = null;
     private Node<E> tail = null;

     public boolean isEmpty(){
         return head == tail;
     }

     public void put(E data){
         Node<E> newNode = new Node<E>(data);
         if(head==null && tail==null){//队列为空
             head = newNode;
             tail = newNode;
         }
         else {
             tail.next = newNode;
             tail = newNode;
         }
     }

     public E pop(){
         if(this.isEmpty())
             return null;
         E data = head.data;
         head = head.next;
         return data;
     }

     public int size(){
         Node<E> tmp = head;
         int n = 0;
         while (tmp!=null) {
             n++;
             tmp = tmp.next;
         }
         return n;
     }
 }

　2、list方式实现

 public class MyQueue<E>{
     private Linkedlist<E> list = new Linkedlist<E>();
     private int size = 0;
     public synchronized void put(E e){
         list.addLast(e);
         size++;
     }

     public synchronized E pop(){
         size--;
         return list.removeFrist();
     }

     public synchronized boolean empty(){
         return size == 0;
     }

     public synchronized int size(){
         return size;
     }
 }