@Override
        public int compare(BaseDanmaku obj1, BaseDanmaku obj2) {
            if (mDuplicateMergingEnable && DanmakuUtils.isDuplicate(obj1, obj2)) {
                return 0;
            }
            return Float.compare(obj2.getTop(), obj1.getTop());
        }
this type is used to iterate/remove/insert elements, not support sub/subnew
app/src/main/java/com/sunnyweather/android/flame/master/flame/danmaku/danmaku/model/IDanmakus.java