使用底部导航栏的ViewPager不能滑动片段。

Question

我希望能够滑动底部给出的标签页。为此，我使用了这个教程中介绍的BottomNavigationView和ViewPager。下面是我的代码：

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=".MainActivity">
    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/navigation"
        android:layout_alignParentTop="true"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        app:menu="@menu/bottom_navigation_items"
        android:background="@color/colorPrimary"
        app:itemIconTint="@color/colorAccent"
        app:itemTextColor="@android:color/white"></android.support.design.widget.BottomNavigationView>
</RelativeLayout>

Java代码是

    public class MainActivity extends AppCompatActivity {
    BottomNavigationView bottomNavigationView;
    ViewPager viewPager;
    MenuItem prevMenuItem;
    FragmentWallet fragmentWallet;
    FragmentNavigationDrawer fragmentNavigationDrawer;
    FragmentHome fragmentHome;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bottomNavigationView = (BottomNavigationView) findViewById(R.id.navigation);
        viewPager = (ViewPager) findViewById(R.id.viewpager);
        bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {

                switch (item.getItemId()) {
                    case R.id.action_menu_home:
                        viewPager.setCurrentItem(0);
                        break;
                    case R.id.action_menu_wallet:
                        viewPager.setCurrentItem(1);
                        break;
                    case R.id.action_menu_navigation_d:
                        viewPager.setCurrentItem(2);
                        break;
                }

                return false;
            }
        });
        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                if (prevMenuItem != null) {
                    prevMenuItem.setChecked(false);
                } else {
                    bottomNavigationView.getMenu().getItem(0).setChecked(false);
                }
                Log.d("page", "onPageSelected: " + position);
                bottomNavigationView.getMenu().getItem(position).setChecked(true);
                prevMenuItem = bottomNavigationView.getMenu().getItem(position);

            }


            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
        viewPager.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                return true;
            }
        });
        setupViewPager(viewPager);

    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
        fragmentHome = new FragmentHome(); // this should be in `FragmentPagerAdapter.getItem()`
        fragmentWallet = new FragmentWallet(); // this should be in `FragmentPagerAdapter.getItem()`
        fragmentNavigationDrawer = new FragmentNavigationDrawer(); // this should be in `FragmentPagerAdapter.getItem()`

        viewPagerAdapter.addFragment(fragmentHome); // this can cause crashes
        viewPagerAdapter.addFragment(fragmentWallet); // this can cause crashes
        viewPagerAdapter.addFragment(fragmentNavigationDrawer); // this can cause crashes
        viewPager.setAdapter(viewPagerAdapter);
    }
}

View Pager Adapter代码如下：

 public class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>(); // this line can cause crashes

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }
    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFragment(Fragment fragment) {
        mFragmentList.add(fragment);  // this line can cause crashes
    }
}

它可以很好地导航到另一个片段，但它不能滑动片段。请帮忙，或者我需要转换其他解决方案。

- Kiran S Kulkarni

Answer 1

Remove this part:

viewPager.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            return true;
        }
    });

- Pavel Kuznetsov