1. Error as follows:

2. Causes of errors:

The problems caused by the first situation:

Solution: in inflate (R.l ayout layout2, Container), should be changed to inflate (R.l ayout. Layout2, null); Actually the best written inflate (R.l ayout layout2, container, false); So this is a good way to write it;

The second situation causes problems:

Viewpager1 is not in the activity_main1 layout;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main1);
    ViewPager mViewPager = findViewById(R.id.viewpager1);
Copy the code

Solutions:

ViewPager mViewPager = findViewById(R.id.viewpager1); Reference ViewPager in the layout where viewPager1 resides;