Java中队列的代码实现

用链表来实现队列这种数据结构

public class Node<E> {
	E data;
	Node next;

	public Node(E data) {
		this.data = data;
	}

}

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

	public boolean isEmpty() {// 如果头和尾都是null，认为是空的
		if (head == null && tail == null) {
			return true;
		} else {
			return false;
		}
	}

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

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

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

}

用数组实现队列

实现多线程安全，增加了对队列操作的同步

import java.util.LinkedList;

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.removeFirst();
	}

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

	public synchronized int size() {
		return size;
	}

}