Why no title?

I have tried to set both in layout file(xml) or activity file(java), but the title I set never show.

activity_main.xml

MainActivity.java
in onCreate()
navigationTabBar = (NavigationTabBar) findViewById(R.id.navigationTabBar);
models = new ArrayList<>();
models.add(
new NavigationTabBar.Model.Builder(
getResources().getDrawable(R.mipmap.gift),
Color.parseColor("#aaffbb")
).title("账本").badgeTitle("aaaa").build()
);
models.add(
new NavigationTabBar.Model.Builder(
getResources().getDrawable(R.mipmap.clothing),
Color.parseColor("#785355")
).title("明细").badgeTitle("bbbb").build()
);
models.add(
new NavigationTabBar.Model.Builder(
getResources().getDrawable(R.mipmap.shopping),
Color.parseColor("#214542")
).title("统计").badgeTitle("cccc").build()
);
models.add(
new NavigationTabBar.Model.Builder(
getResources().getDrawable(R.mipmap.eating),
Color.parseColor("#123456")
).title("设置").badgeTitle("dddd").build()
);
navigationTabBar.setModels(models);
navigationTabBar.setTitleMode(NavigationTabBar.TitleMode.ALL);
navigationTabBar.setBadgeGravity(NavigationTabBar.BadgeGravity.TOP);
navigationTabBar.setBadgePosition(NavigationTabBar.BadgePosition.CENTER);
navigationTabBar.setTitleSize(30);
navigationTabBar.setIsTitled(true);

api 26
What should I do to make it show title? thx!