20162327WJH使用队列：模拟票务站台代码分析

20162327WJH使用队列：模拟票务站台代码分析

用链队实现队列的情况

1、用链表实现队列的代码

• 关键方法代码及补全代(LinkedOueue类)

 public void enqueue(T element) {
        LinearNode<T> node = new LinearNode<T>(element);
        if (count==0)
            front = node;
        else
            rear.setNext(node);

        rear = node;
        count++;
    }
    public T dequeue() throws Exception {
        if (count==0)
            throw new Exception("队列是空的！");
        T result = front.getElement();
        front = front.getNext();
        count--;
        if (isEmpty())
            rear = null;
        return result;
    }
    public T first() throws Exception {
        if (count==0)
            throw new Exception("队列是空的！");
        return front.getElement();
    }

    public boolean isEmpty() {
        return (count == 0);
    }
    public int size() {
        return count;
    }
    public String toString() {
        String result = "<top of Queue>
";
        LinearNode current = front;
        while (current != null)
        {
            result = result + (current.getElement()).toString() + "
";
            current = current.getNext();
        }
        return result + "<bottom of Queue>";
    }
}

• 节点类

public class LinearNode<T> {
    private LinearNode<T> next;
    private T element;
    public LinearNode() {
        next = null;
        element = null;
    }
    public LinearNode(T elem) {
        next = null;
        element = elem;
    }
    public LinearNode<T> getNext() {
        return next;
    }
    public void setNext(LinearNode<T> node) {
        next = node;
    }
    public T getElement() {
        return element;
    }
    public void setElement(T elem) {
        element = elem;
    }
}

2、用IDEA进行单步跟踪

3、遇到的问题及解决过程

二、用循环数组实现队列

1、用链表实现队列的代码

• 关键方法代码及补全代码(CircularArrayQueue类)

 public void enqueue (T element){
        if(count == queue.length){
            expandCapacity();
            queue[rear] = element;
            rear = (rear+1) % queue.length;
            count++;
        }
    }
    public void expandCapacity()
    {
        T[]larger = (T[])(new Object[queue.length*2]);
        for(int index = 0;index<count;index++){
            larger[index] = queue[(front + index) % queue.length];
            front = 0;
            rear = count;
            queue = larger;
        }
    }
    public T dequeue() throws Exception {
        if (count == 0)
            throw new Exception("错误代码！");
        T a = queue[front];
        queue[front] = null;
        front = (front + 1) % queue.length;
        count--;
        return a;
    }

2、用IDEA进行单步跟踪

3、遇到的问题及解决过程