20162316刘诚昊 用链表实现队列

20162316刘诚昊 2017-2018-2 《Java程序设计》用链表实现队列

实验要求

1 参考程序15.5给出方法deque,first,isEmpty,size,toString的定义，完成LinkedeQueue类并用Junit进行单元测试（正常，异常，边界情况）
2 提交测试代码运行截图，要全屏，包含自己的学号信息
3课下把代码推送到代码托管平台

过程

1.补全书上的代码（我在enqueue操作里面做了一些调整）

public class LinkedeQueue<T> {
    private int count = 0;
    private LinearNode<T> front ,rear;
    public LinkedeQueue(){
        front = rear = null;
    }
    public void enqueue (T element){
        LinearNode<T> NEW = new LinearNode<T>(element);
        if (count == 0){
            front=NEW;
        }
        if (count == 1){
           rear.setNext(NEW);
           front.setNext(rear.getNext());
        }
        if (count >= 2){
           rear.setNext(NEW);
        }
        rear = NEW;
        count++;
    }

    public T dequeue() throws EmptyCollectionException{
        if (count == 0) throw new EmptyCollectionException("Dequeue operation failed. " + "The queue is empty.");
        T result = front.getElement();
        front = front.getNext();
        count--;

        return result;
    }

    public T first() throws EmptyCollectionException {
        if (count == 0) throw new EmptyCollectionException("Dequeue operation failed. " + "The queue is empty.");
        T result = front.getElement();
        return result;
    }

    public boolean isEmpty() {
        return (count == 0);
    }

    public int size() {
        return count;
    }

    public String toString() {
        LinearNode<T> S = front;
        String sr = "";
        ad:
        while(count != 0){
            sr = sr + " " + S.getElement();
            if(count == 0)
                break ad;
            S = S.getNext();
            count --;
        }
        return  sr;
    }
}

2.测试代码：

public class LinkedeQueueTest extends TestCase {
    LinkedeQueue L = new LinkedeQueue();
    public void testDequeue() throws Exception {
        L.enqueue(01);
        L.enqueue(02);
        L.enqueue(03);
        assertEquals(01,L.dequeue());
        assertEquals(02,L.dequeue());
        assertEquals(03,L.dequeue());
    }

    public void testFirst() throws Exception {
        L.enqueue(01);
        L.enqueue(02);
        assertEquals(01,L.first());
    }

    public void testIsEmpty() throws Exception {
        assertEquals(true,L.isEmpty());
        L.enqueue(01);
        assertEquals(false,L.isEmpty());
    }

    public void testSize() throws Exception {
        L.enqueue(01);
        L.enqueue(02);
        L.enqueue(03);
        assertEquals(3,L.size());
    }

    public void testToString() throws Exception {
        L.enqueue(01);
        L.enqueue(02);
        L.enqueue(03);
        assertEquals(" " + 01 + " " + 02 + " " +03,L.toString());
    }

}