Java实现队列

 使用数组简单模拟队列

缺点：无法再次利用已经取出元素的位置，因为front一直向数组末端移动

public class ArrQueue {
    public static void main(String[] args) {
        ArrayQueue arrayQueue = new ArrayQueue(5);
        //测试方法
        arrayQueue.addQueue(1);
        arrayQueue.addQueue(2);
        arrayQueue.addQueue(3);
        arrayQueue.showQueue();
        System.out.println("----------------------------");

        System.out.println(arrayQueue.getQueue());
        System.out.println(arrayQueue.headQueue());
        arrayQueue.showQueue();
        System.out.println("----------------------------");

        arrayQueue.addQueue(4);
        arrayQueue.addQueue(5);
        System.out.println(arrayQueue.isFull());
        System.out.println(arrayQueue.addQueue(6));
        System.out.println("----------------------------");

        System.out.println(arrayQueue.getQueue());
        System.out.println(arrayQueue.getQueue());
        System.out.println(arrayQueue.getQueue());
        System.out.println(arrayQueue.getQueue());
//        System.out.println(arrayQueue.getQueue()); //Exception 队列为空，无法删除
        System.out.println(arrayQueue.isEmpty());
        System.out.println("----------------------------");

    }

}

class ArrayQueue {
    private int maxSize;//最大容量
    private int front;//队头元素的前一个位置
    private int rear;//队尾
    private int[] arr;//该数组用于存放数据，模拟队列

    public ArrayQueue(int maxSize) {
        this.maxSize = maxSize;
        this.front = -1;
        this.rear = -1;
        this.arr = new int[maxSize];
    }

    
    public boolean isFull() {
        return rear == maxSize - 1;
    }

    
    public boolean isEmpty() {
        return front == rear;
    }

    
    public boolean addQueue(int n) {
        //判断队列是否为满
        if (isFull())
            return false;
        arr[++rear] = n;
        return true;
    }

    
    public int getQueue() {
        if (isEmpty())
            throw new RuntimeException("队列为空");
        return arr[++front];
    }

    
    public void showQueue() {
        if (isEmpty()) {
            System.out.println("队列为空");
        }
        for (int i = front + 1; i <= rear; i++)
            System.out.println(arr[i]);
    }

    
    public int headQueue() {
        if (isEmpty())
            throw new RuntimeException("队列为空");
        return arr[front + 1];
    }


}