Find Median from Data Stream

public class MedianFinder {
    private PriorityQueue<Integer> maxQueue;
    private PriorityQueue<Integer> minQueue;
    
    public MedianFinder() {
        maxQueue = new PriorityQueue<>(Collections.reverseOrder());
        minQueue = new PriorityQueue<>();
    }

    // Adds a number into the data structure.
    public void addNum(int num) {
        maxQueue.offer(num);
        minQueue.offer(maxQueue.poll());
        if (maxQueue.size() < minQueue.size()) {
            maxQueue.offer(minQueue.poll());
        }
    }

    // Returns the median of current data stream
    public double findMedian() {
        if (maxQueue.size() != minQueue.size()) {
            return maxQueue.peek();
        }
        return (double)(maxQueue.peek() + minQueue.peek()) / 2.0;
    }
};

// Your MedianFinder object will be instantiated and called as such:
// MedianFinder mf = new MedianFinder();
// mf.addNum(1);
// mf.findMedian();