ViewPager2实现懒加载

1.如何使用ViewPager2

implementation 'com.google.android.material:material:1.2.0-alpha06'

2.在布局文件中添加

3.创建适配器

public class ViewPager2Adapter extends FragmentStateAdapter {
    private List fLists = new ArrayList<>();

    public ViewPager2Adapter(@NonNull FragmentActivity fragmentActivity, List fLists) {
        super(fragmentActivity);
        this.fLists = fLists;
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        return fLists.get(position);
    }

    @Override
    public int getItemCount() {
        return fLists.size();
    }
}

然后再MainActivity中

List fLists = new ArrayList<>();
        fLists.add(new HomeFragment());
        fLists.add(new FaberFragment());
        fLists.add(new DealFragment());
        fLists.add(new ContractFragment());
        fLists.add(new AssetFragment());
        ViewPager2Adapter adapter = new ViewPager2Adapter(this, fLists);
        mBinding.vp2.setAdapter(adapter);
        mBinding.vp2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            @Override
            public void onPageSelected(int position) {
                super.onPageSelected(position);
                mBinding.bnv.getMenu().getItem(position).setChecked(true);
            }
        });
        mBinding.bnv.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                switch (item.getItemId()) {
                    case R.id.menu_hone:
                        mBinding.vp2.setCurrentItem(0);
                        return true;
                    case R.id.menu_faber:
                        mBinding.vp2.setCurrentItem(1);
                        return true;
                    case R.id.menu_deal:
                        mBinding.vp2.setCurrentItem(2);
                        return true;
                    case R.id.menu_contract:
                        mBinding.vp2.setCurrentItem(3);
                        return true;
                    case R.id.menu_asset:
                        mBinding.vp2.setCurrentItem(4);
                        return true;
                }
                return false;
            }
        });

在单独使用ViewPager2的时候我们发现具有懒加载效果，但是当我们结合tablayout使用的时候却是滑动ViewPager2的时候是懒加载效果，但当我们点击的时候发现没有懒加载效果，这并不是我们想要的，解决方法在点击的时候设置setCurrentItem（position）的时候要加上false setCurrentItem(position,false); 就实现了懒加载效果