忽略某些条件的循环队列toString方法

Question

当我调用我的 toString（） 方法时，如果在索引环绕（前面）之后，它不起作用

public class driver {
public static void main(String[] args) {

    Queue queue = new Queue(4);
    System.out.println(queue);
    queue.enqueue(1);
    queue.enqueue(2);
    queue.enqueue(3);
    queue.enqueue(4);
    System.out.println(queue);
    queue.dequeue();
    System.out.println(queue);

    queue.dequeue();
    System.out.println(queue);

    queue.enqueue(5);
    queue.enqueue(6);

    System.out.println(queue);


}

public static class Queue {

    int front;
    int rear;
    int capacity;
    int[] queue;

    public Queue(int size) {
        this.capacity = size;
        this.front = this.rear = -1;
        this.queue = new int[capacity];
    }

    @Override
    public String toString() {
        String str = "";
        if (front > rear) {
            int i = front;
            while (i != rear) {
                str = str + queue[i % queue.length] + " ";
                i++;
            }
            //str= str+queue[rear];
        }
        if (front < rear) {
            for (int i = front; i <= rear; i++) {
                str = str + queue[i];
            }
        }
        if (front == rear) {
            str = "This Queue is Empty. Please Enqueue";
        }

        return str;
    }


    public boolean isFull() {

        return ((rear == this.queue.length - 1 && front == 0) || rear == front - 1);

    }

    public boolean isEmpty() {
        return (front == -1);
    }

    public void enqueue(int elem) {
        if (isFull()) {
            System.out.println("Full Queue - dequeue an element if you need to add an element in the queue");
        } else {
            if (isEmpty()) {
                this.queue[++rear] = elem;
                front = 0;
            } else {
                rear = (rear + 1) % this.queue.length;
                this.queue[rear] = elem;
            }
        }
    }

    public int dequeue() {
        if (isEmpty()) {
            System.out.println("empty queue. Enqueue some elments. ");
            return -1;
        } else {
            int store = this.queue[front];

            if (rear == front) {
                front = rear = -1;
            } else {

                front = front + 1 % this.queue.length;

            }
            return store;

        }

    }

}

*这里也有一个返回的花括号，lol仍然是发布问题的新手。P、 S有人能帮我吗？因为显然我在问题中发布了太多代码。有什么变通办法吗？

Answer 1

问题是toString的time循环中的i。

考虑< code>front = 3和< code>rear = 1的情况，然后从< code>i = front = 3开始循环。但是，您会一直递增，直到达到< code>i == rear，这种情况从< code>rear开始就不会发生了

一旦达到< code >容量，您希望< code>i循环回到< code>0。您可以通过删除< code>i 并用< code>i = (i 1) % capacity替换它来实现这一点；

看起来您的代码中有一个不同的bug，因为当我运行它时，我看到

This Queue is Empty. Please Enqueue
1234
234
34
3 4 5

你需要自己弄清楚这一点。

您甚至可以将其压缩为单个for语句

for(int i = front; i != rear; i = (++i) % capacity)