Android 底部导航 用fragment的方式

//获取到fragmentManager 
fragmentManager = getSupportFragmentManager();

//切换隐藏掉全部的Fragment
private void hideAllFragment() {
        for (int i = 0; i < fragmentArrayList.size(); i++) {
            fragmentManager.beginTransaction().hide(fragmentArrayList.get(i)).commit();
        }
    }
...
//当导航点击的时候进行切换
                if (fragmentArrayList.get(position).isAdded()) {
                    hideAllFragment();
                    fragmentManager.beginTransaction().show(fragmentArrayList.get(position)).commit();
                } else {
                    hideAllFragment();
                    fragmentManager.beginTransaction().add(R.id.contentContainer, fragmentArrayList.get(position))
                            .show(fragmentArrayList.get(position))
                            .commit();
}
...