链队列的实现

package com.wxisme.linkqueue;

import java.util.Scanner;

/**
 * 链队列的实现
 * @time 2015/8/16 0:16
 * @author wxisme
 *
 */
public class LinkQueue<T> {
	
	private class Node {
		private T data;
		private Node next;
		
		public Node() {}
		
		public Node(T data) {
			this.data = data;
		}
	}
	
	private Node front;   /*队头*/
	private Node rear;    /*队尾*/
	private int size;     /*长度*/
	
	public LinkQueue() {
		front = null;
		rear = null;
	}
	public LinkQueue(T data) {
		front = new Node(data);
		rear = front;
		size ++;
	}
	//队列的长度
	public int size() {
		return size;
	}
	//从队尾入队
	public void add(T data) {
		if(front == null) {
			front = new Node(data);
			rear = front;
			size ++;
		}
		else {
			Node node = new Node(data);
			rear.next = node;
			rear = node;
			size ++;
		}
	}
	//从队头出队
	public T remove() {
		T t = null;
		if(front != null) {
			t = front.data;
			Node node = front;
			front = front.next;
			node.next = null;//释放对头元素的引用，等待垃圾回收。
			size --;
		}
		else {
			try {
				throw new Exception("队列已经为空，不能移除元素！");
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return t;
	}
	//读取对头元素
	public T peek() {
		if(front == null) {
			try {
				throw new Exception("队列为空，不能读取对头元素！");
			} catch (Exception e) {
				e.printStackTrace();
			}
			return null;
		}
		else {
			return front.data;
		}
	}
	//清空队列
	public void clear() {
		front = rear = null;
		size = 0;
	}
	//判断是否为空
	public boolean isEmpty() {
		return size==0;
	}
	
	public String toString() {
		if(isEmpty()) {
			return "[]";
		}
		else {
			StringBuilder str = new StringBuilder("[" + front.data);
			for(Node node=front.next; node!=null; node=node.next) {
				str.append(","+node.data);
			}
			str.append("]");
			return str.toString();
		}
	}
	/**
	 * 测试代码
	 * @param args
	 */
	public static void main(String[] args) {
		LinkQueue<Character> queue = new LinkQueue<Character>();
		Scanner scan = new Scanner(System.in);
		for(int i=0; i<5; i++) {
			queue.add((char)(‘a‘+i));
		}
		System.out.println(queue);
		queue.remove();
		System.out.println(queue);
		System.out.println("队列是否为空：" + queue.isEmpty());
		System.out.println("队列的长度：" + queue.size());
		System.out.println("队头元素为：" + queue.peek());
		System.out.println("清空队列");
		queue.clear();
		System.out.println("队列是否为空：" + queue.isEmpty());
	}
	
}