接口类：

/**
 * 〈天道酬勤〉
 *
 * @author wu
 * @create 2019/4/15 21:26
 * MyQueue: enqueue(), dequeue(), isEmpty()
 */
public interface MyQueue {
        //入队
        boolean enqueue(Object obj);
        //出队
        boolean dequeue();
        //判空
        boolean isEmpty();
}

接口实现：

/**
 * 〈天道酬勤〉
 *
 * @author wu
 * @create 2019/4/15 21:37
 */
public class MyQueueImpl implements MyQueue {
    private static final int MAX_CAPACITY = Integer.MAX_VALUE - 8;
    private static final int DEFAULT_CAPACITY = 10;
    private Object[] objs;
    private int front;  //队列头，允许删除
    private int rear;   //队列尾，允许插入

    public MyQueueImpl() {
        this(DEFAULT_CAPACITY);
    }

    public MyQueueImpl(int capacity) {
        if (capacity < 0 || capacity > MAX_CAPACITY) {
            throw new IllegalArgumentException("capacity=" + capacity);
        }
        objs = new Object[capacity];
    }

    @Override
    public boolean enqueue(Object obj) {
        if (rear == objs.length - 1) {
            this.grow();

        } else {
            objs[rear++] = obj;
        }
        return true;
    }

    private void grow() {   //扩容
        objs = Arrays.copyOf(objs, objs.length + (objs.length>>1));
    }

    @Override
    public boolean dequeue() {
        if (isEmpty()) {
            throw new EmptyStackException();
        } else {
            Object ojs = (Object) objs[front];  
            objs[front++] = null;     //释放队列的front端的元素
            return true;
        }
    }

    @Override
    public boolean isEmpty() {
        return rear == front ? true : false;
    }
}