Android的BottomNavigationView设置默认选中怎么写

Question

我这样写报错

        navigationView = (BottomNavigationView) findViewById(R.id.navigation);
        navigationView.getChildAt(1).setSelected(true);

 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setSelected(boolean)' on a 

Answer 1

setSelectedItemId(int itemId)

尝试一下这个方法。
参考：BottomNavigationView

Answer 2

补充楼上：
navigation.setSelectedItemId(navigation.getMenu().getItem(position).getItemId());