ViewPager嵌套Fragment

1. 新建4个Fragment；

2. 新建ViewPagerAdapter继承FragmentPagerAdapter;
   public class ViewpagerAdapter extends FragmentPagerAdapter {

       private ArrayList<Fragment> arrayList;
   
       public ViewpagerAdapter(@NonNull FragmentManager fm,ArrayList<Fragment> arrayList) {
           super(fm);
           this.arrayList=arrayList;
       }
   
       @NonNull
       @Override
       public Fragment getItem(int position) {
           return arrayList.get(position);
       }
   
       @Override
       public int getCount() {
           return arrayList.size();
       }
   }
   

3. 在MainActivity中为ViewPager绑定适配器；

   arrayList=new ArrayList<>();
       arrayList.add(new Fragment1());
       arrayList.add(new Fragment2());
       arrayList.add(new Fragment3());
       arrayList.add(new Fragment4());
       viewpagerAdapter= new ViewpagerAdapter(getSupportFragmentManager(),arrayList);
       viewpager.setAdapter(viewpagerAdapter);