老师好，这是基于我自己的理解写的循环队列，也就是数组中第一个元素的下标是front，数组中最后一个元素的下标是tail，代码如下：
public interface Queue {
public int getSize();
public int getCapacity();
public boolean isEmpty();
public E front();
public void enqueue(E e);
public E dequeue();
}

public class MyLoopQueue implements Queue {
private E[] data;
private int front;
private int tail;
private int size;

public MyLoopQueue(int capacity) {
data = (E[])new Object[capacity];
}

public MyLoopQueue() {
this(10);
}

@Override
public int getSize() {
return size;
}

@Override
public int getCapacity() {
return data.length;
}

@Override
public boolean isEmpty() {
return size == 0;
}

@Override
public E front() {
if(isEmpty()) {
throw new IllegalArgumentException(“还没有向队列添加元素。”);
}
return data[front];
}

@Override
public void enqueue(E e) {
if(tail == data.length - 1 || (front == tail && front != 0 && tail != 0)) {
resize(getCapacity() * 2);
}

data[tail + 1] = e;
tail = ++tail % data.length;
size++;

}

private void resize(int newCapacity) {
E[] newData = (E[])new Object[newCapacity];
for (int i = 0; i < size; i++) {
newData[i] = data[(front + i) % data.length];
}

data = newData;
newData = null;
front = 0;
tail = size - 1;

}

@Override
public E dequeue() {
if(isEmpty())
throw new IllegalArgumentException(“Cannot dequeue from an empty queue.”);

E res = data[front];
data[front] = null;
front = (front + 1) % data.length;
size--;

if(size == getCapacity() /4 && getCapacity() / 2 != 0) {
    resize(getCapacity() / 2);
}

return res;

}

@Override
public String toString() {
StringBuilder res = new StringBuilder();
res.append(String.format(“Loop queque size = %d, capacity = %d\n”, size, getCapacity()));

for (int i = front; i == tail && front != 0 && tail != 0; i = (i + 1) % data.length) {
  res.append(data[i]);
  if((i + 1) % data.length != tail) {
    res.append(",");
  }
}

return res.toString();

}

public static void main(String[] args) {
LoopQueue lq = new LoopQueue<>();
for (int i = 0; i < 10; i++) {
lq.enqueue(i);
System.out.println(lq);
if(i % 3 == 2) {
lq.dequeue();
System.out.println(lq);
}
}
}
}

麻烦老师有空看看我这样写是否可以。辛苦了老师，我问的问题不少。