java - ViewPager2 刷卡时闪烁/重新加载

Question

我正在尝试使用新的 ViewPager2 构建一个 Android 应用程序。我添加了两个 ViewPagers，由一个 View 分隔，当您滑动时，两个 ViewPager 都应该移动。两个 View 寻呼机都在正确移动，但在手势完成后，滑动 View 会闪烁，非滑动 View 会重新加载，如附加的 gif 所示。这是我的 Activity、ViewPagerAdapter 和 Fragment 代码。感谢任何帮助

    public class MainActivity extends FragmentActivity {

    ActivityMainBinding viewBinding;

    MyPager adapter1, adapter2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        viewBinding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        List<String> data = populateData();

        adapter1 = new MyPager(this, data);
        adapter2 = new MyPager(this, data);

        viewBinding.viewPager.setAdapter(adapter1);
        viewBinding.viewPager2.setAdapter(adapter2);

        viewBinding.viewPager2.setOffscreenPageLimit(data.size());
        viewBinding.viewPager.setOffscreenPageLimit(data.size());

        viewBinding.viewPager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {

            @Override
            public void onPageScrolled(final int position, final float positionOffset, final int positionOffsetPixels) {
                viewBinding.viewPager2.scrollTo(positionOffsetPixels, 0);
            }

            @Override
            public void onPageScrollStateChanged(final int state) {
                viewBinding.viewPager2.setCurrentItem(viewBinding.viewPager.getCurrentItem(), true);
            }
        });
        viewBinding.viewPager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {

            @Override
            public void onPageScrolled(final int position, final float positionOffset, final int positionOffsetPixels) {
                viewBinding.viewPager.scrollTo(positionOffsetPixels, 0);
            }

            @Override
            public void onPageScrollStateChanged(final int state) {
                viewBinding.viewPager.setCurrentItem(viewBinding.viewPager2.getCurrentItem(), true);
            }
        });

    }
    private List<String> populateData() {
        List<String> data = new ArrayList<>();
        for (int x = 0; x < 10; x++) {
            String derril = "derril " + x;
            data.add(derril);
        }
        return data;
    }
}

public class MyPager extends FragmentStateAdapter {

    List<String> data;

    public MyPager(@NonNull FragmentActivity fragmentActivity, List<String> data) {
        super(fragmentActivity);
        this.data = data;
    }

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

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

public class DerrilFragment extends Fragment {

    PizzaBinding viewBinding;

    String data;

    private DerrilFragment(String data) {
        this.data = data;
    }

    public static DerrilFragment newInstance(String data) {
        return new DerrilFragment(data);
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

        viewBinding = DataBindingUtil.inflate(inflater, R.layout.pizza, container, false);

        viewBinding.text.setText(data);

        return viewBinding.getRoot();

    }
}

Answer 1

可以通过RecyclerView实现。

class MainActivity : AppCompatActivity() {
    private var isFirstFocused = false

    private val helper: SnapHelper = LinearSnapHelper()
    private val helper2: SnapHelper = LinearSnapHelper()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        recycler1.addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                super.onScrolled(recyclerView, dx, dy)
                if (isFirstFocused) recycler2.scrollBy(dx, dy)
            }
        })
        recycler2.addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                super.onScrolled(recyclerView, dx, dy)
                if (!isFirstFocused) recycler1.scrollBy(dx, dy)
            }
        })
        recycler2.setOnTouchListener { v, event ->
            if (event.action  != null && event.action == MotionEvent.ACTION_DOWN ) {
                isFirstFocused = false
                return@setOnTouchListener  true
            }
            return@setOnTouchListener false
        }
        recycler1.setOnTouchListener { v, event ->
            if (event.action  != null && event.action == MotionEvent.ACTION_DOWN ) {
                isFirstFocused = true
                return@setOnTouchListener  true
            }
            return@setOnTouchListener false
        }
        helper.attachToRecyclerView(recycler1)
        helper2.attachToRecyclerView(recycler2)
        val manager = LinearLayoutManager(this, RecyclerView.HORIZONTAL, false)
        val manager2 = LinearLayoutManager(this, RecyclerView.HORIZONTAL, false)
        recycler1.layoutManager = manager
        recycler2.layoutManager = manager2
        recycler2.adapter = Adapter(items)
        recycler1.adapter = Adapter(items)
    }

    private val items = listOf("One", "Two", "Three")

}

class Adapter(val list: List<String>) : RecyclerView.Adapter<Adapter.Holder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Holder {
        val view = LayoutInflater.from(parent.context).inflate(
            R.layout.activity_listview,
            parent,
            false
        )
        return Holder(view)
    }

    override fun onBindViewHolder(holder: Holder, position: Int) {
        holder.itemView.text_view.text = list[position]
    }

    override fun getItemCount() = list.size

    class Holder(view: View) : RecyclerView.ViewHolder(view)
}