java - 像队列一样使用数组

Question

我的队列类有问题。队列是基于数组的。当队列项到达数组末尾时，应将它们添加到数组开头。如果队列已满，则应删除并显示最旧的队列项目。当插入第 8 个元素时，我无法显示已删除的最旧项目。

当用户选择显示前 3 个客户的姓名时，代码应将它们从队列中一一删除(先进先出)，并在删除时显示它们。

输入和输出示例:

队列输入是:A乙CdeFGh

队列输出是:H乙CdeF克

删除的项目是:h

预期输出应为:

H乙CdeFG删除的项目是:


因此它将最后插入的项目移动到数组的前面，但是我如何显示“项目已删除是:a”我的代码是:

public class MyQueue {

    private final static int CAPACITY = 7;
    static String qitems[] = new String[CAPACITY];
    private static int front = 0, end = 0, count=0;

    public void addqueue(String name) {
        qitems[end] = name;
        count++;
        if(count==7) {
            takequeue();
            System.out.println("Queue is full");
        }
        end = (end + 1) % 7;
    }

    public void takequeue() {
        System.out.println("Item removed:"+qitems[front]);
        front = (front +1) % 7;
    }

    public void displayNames() {
        System.out.println(" 3 names entered are: ");
        for (int x = 0; x < 3; x++) {
            System.out.println(qitems[x]);
        }
    }
}

Answer 1

public class QWithArray {

    String[] qItems;
    int front;
    int end;
    int current;

    QWithArray(int CAPACITY) {
        qItems = new String[CAPACITY];
        current = 0;
        front = -1;
        end = -1;
    }

    public void addqueue(String element) {
        if (current == qItems.length) {
            System.out.println("Item removed was: " + qItems[(front + 1) % qItems.length]);
        }

        front = (front + 1) % qItems.length;
        qItems[front] = element;
        current++;

        if (end == -1) {
            end = front;
        }
    }

    public String takequeue() {
        if (current == 0) {
            System.out.println("Queue is empty; can't remove.");
            return null;
        }

        String result = qItems[end];
        qItems[end] = null;

        end = (end + 1) % qItems.length;
        current--;

        if (current == 0) {
            front = -1;
            end = -1;
        }
        return result;
    }

    public static void main(String[] args) {
        QWithArray q = new QWithArray(7);
        q.addqueue("a");
        q.addqueue("b");
        q.addqueue("c");
        q.addqueue("d");
        q.addqueue("e");
        q.addqueue("f");
        q.addqueue("g");
        System.out.println(Arrays.toString(q.qItems));

        q.addqueue("h");
        System.out.println(Arrays.toString(q.qItems));
    }
}

输出为:

[a, b, c, d, e, f, g]

Item removed was: a

[h, b, c, d, e, f, g]