链队

public class LinkedQueue {

	QueueHead qh = new QueueHead();
	
	boolean empty() {
		return qh.front == null;        //or qh.rear == null
	}
	
	void enQueue(int e) {
		QNode q = new QNode(e);
		if(empty()) {
			qh.front = q;
			qh.rear = q;
		} else {
			qh.rear.next = q;
			qh.rear = q;
		}
	}
	
	int[] deQueue() {
		int[] arr = new int[2];
		if(qh.rear == null) {
			arr[0] = 0;
			return arr;
		}
		arr[0] = 1;
		arr[1] = qh.front.data;
		if(qh.front.next == null) {
			qh.front = qh.rear = null;
		} else {
			qh.front = qh.front.next;
		}
		return arr;
	}
	
	void display() {
		QNode p = qh.front;
		while(p != null) {
			if(p.next == null) {
				System.out.println(p.data);
			} else {
				System.out.print(p.data + "->");
			}
			p = p.next;
		}
	}
	
	public static void main(String[] args) {
		LinkedQueue sq = new LinkedQueue();
		System.out.println(sq.empty());
		sq.enQueue(4);
		sq.enQueue(5);
		sq.display();
		sq.deQueue();
		sq.deQueue();
		System.out.println(sq.empty());
		sq.display();
		sq.enQueue(1);
		sq.enQueue(3);
		sq.display();
		sq.deQueue();
		sq.display();
		sq.enQueue(2);
		sq.deQueue();
		sq.display();
		System.out.println(sq.empty());

	}

}

class QNode {
	int data;
	QNode next;
	QNode(){}
	QNode(int e) {
		data = e;
	}
}

class QueueHead {
	QNode front;
	QNode rear;
	public QueueHead() {}
}

结果：

true
4->5
true
1->3
3
2
false