在刷新的时候，Indicator 不刷新

[XiaoMaGe258]

我在Fragment里，网络获取bannerList列表：
第一次，bannerList有两个，setRvBannerData(bannerList);后，有两个圆点。
第二次，bannerList有1个，setRvBannerData(bannerList);后，还是有两个圆点，没有刷新。
能留一个刷新方法么？

[XiaoMaGe258]

补充：从1个变成2个，会刷新出来。 但是从2个变成1个，没有刷新。

求帮助！

[XiaoMaGe258]

这是我根据demo改的。请帮忙看下应该怎么改，感谢！非常感谢！
public class MainActivity extends AppCompatActivity {
List banners = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button btn = (Button) findViewById(R.id.btn_update);

    final RecyclerViewBanner recyclerViewBanner2 = (RecyclerViewBanner) findViewById(R.id.rv_banner_2);

    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            set1();
            recyclerViewBanner2.setRvBannerData(banners);
        }
    });

    banners.add(new Banner("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1487221110004&di=d6043e4b0c90ddf3ea5096c3d8eb8f58&imgtype=0&src=http%3A%2F%2Fimage.tianjimedia.com%2FuploadImages%2F2014%2F067%2F5116EPAUD762_1000x500.jpg"));
    banners.add(new Banner("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1490438881557&di=e61065ccc8d7b44591e1c4ba8df672ee&imgtype=0&src=http%3A%2F%2Fc.hiphotos.baidu.com%2Fzhidao%2Fpic%2Fitem%2F18d8bc3eb13533fa00428309a0d3fd1f41345b24.jpg"));
    banners.add(new Banner("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1491018668060&di=b96bf4ac065ab547eddc5af24dfbedd5&imgtype=0&src=http%3A%2F%2Fi2.sanwen8.cn%2Fdoc%2F1610%2F704-161024211H3.jpg"));
    recyclerViewBanner2.setRvBannerData(banners);
    recyclerViewBanner2.setOnSwitchRvBannerListener(new RecyclerViewBanner.OnSwitchRvBannerListener() {
        @Override
        public void switchBanner(int position, AppCompatImageView bannerView) {
            Glide.with(bannerView.getContext())
                    .load(banners.get(position).getUrl())
                    .placeholder(R.mipmap.ic_launcher)
                    .into(bannerView);
        }
    });
}

private void set1(){
    banners.clear();
    banners.add(new Banner("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1487221110004&di=d6043e4b0c90ddf3ea5096c3d8eb8f58&imgtype=0&src=http%3A%2F%2Fimage.tianjimedia.com%2FuploadImages%2F2014%2F067%2F5116EPAUD762_1000x500.jpg"));
}

private class Banner {
    String url;
    public Banner(String url) {
        this.url = url;
    }
    public String getUrl() {
        return url;
    }
}

}