数据结构——队列链表实现

package com.shine.test.datastruct;

import java.util.EmptyStackException;

public class LinkQueue<E> {
	
	private Node front,tail;
	class Node {
		E data;
		Node next;
	}
	
	public LinkQueue() {
		 LinkQueue<E>.Node node = new Node();
		 node.data = null;
		 node.next = null;
		 front = tail = node;
	}
	
	public boolean push(E e) {
		LinkQueue<E>.Node temp = new Node();
		temp.data = e;
		temp.next = null;
		tail.next = temp; //当加入第一个元素是应为tail和front指向同一个对象 所以此时相当于front.next =temp,但以后不是
		tail = temp;
		if(temp != null) {
			return true;
		}
		return false;
	}
	
	public E pop() {
		if(front == tail) {
			throw new EmptyStackException();
		}else {
			LinkQueue<E>.Node temp = front.next; 
			E e = temp.data;
			front.next = temp.next;
			
			if(tail == temp) { //当队列中只有一个元素时 需要将队列置空
				tail = front;
			}
			return e;
		}
				 
	}
	public E peek() {
		if(front == tail) {
			throw new EmptyStackException();
		}else {
			LinkQueue<E>.Node temp = front.next; 
			E e = temp.data;
			
			return e;
		}
				 
	}
}