Android TabPagerAdapter：舊版API無法正常工作

Question

我遇到了FragmentPagerAdapter問題。

我已經在我的應用程序的其他部分成功地使用了它，但是現在我遇到了這個討厭的問題：在較老的API上，當我從一個標籤頁滑動到另一個標籤頁時，一切工作都完美無缺，我通過點擊標題來改變標籤，它被選中，但底層的片段沒有改變。

我已經開始認爲這個問題可能是由於這個傳呼機嵌套在另一個片段中。儘管如此，奇怪的是我可以通過刷標籤來改變標籤，但是不能通過點擊標題來改變標籤。

這裏是我的代碼：

public class PetrolStationFragment extends Fragment { 

private PetrolStation mPetrolStation; 

private int mPetrolStationIndex; 

private AppCompatImageView mLogo; 
private TextView mNameTextView; 
private CheckBox mCheckBox; 
private TextView mAddressTextView; 
private TextView mDistanceTextView; 
private Switch mSwitch; 
private GoogleMap mGoogleMap; 

private static TabLayout mTabLayout; 
private static ViewPager mViewPager; 
private static int intItems = 2; 


// Design pattern to instantiate a new fragment. 
public static PetrolStationFragment newInstance(int petrolStationIndex) { 
    Bundle args = new Bundle(); 
    args.putInt(ARG_PETROL_STATION_INDEX, petrolStationIndex); 

    PetrolStationFragment fragment = new PetrolStationFragment(); 
    fragment.setArguments(args); 

    return fragment; 
} 

/********************************************************/ 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    mPetrolStationIndex = getArguments().getInt(ARG_PETROL_STATION_INDEX); 
    mPetrolStation = PetrolStationsArray.get().getItem(mPetrolStationIndex); 
} 

@Override 
public void onPause() { 
    super.onPause(); 
} 

@Override 
public void onResume() { 
    super.onResume(); 
} 

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceStace) { 
    View view = inflater.inflate(R.layout.fragment_petrol_station, container, false); 

    mLogo = (AppCompatImageView) view.findViewById(R.id.ps_logo); 
    mNameTextView = (TextView) view.findViewById(R.id.petrol_station); 
    mCheckBox = (CheckBox) view.findViewById(R.id.checkbox); 
    mAddressTextView = (TextView) view.findViewById(R.id.address); 
    mDistanceTextView = (TextView) view.findViewById(R.id.distance); 
    mSwitch = (Switch) view.findViewById(R.id.on_service); 

    mLogo.setImageDrawable(ContextCompat.getDrawable(getActivity(), getPetrolStationLogo(mPetrolStation.getLogo()))); 
    mNameTextView.setText(mPetrolStation.getName()); 
    mCheckBox.setChecked(mPetrolStation.isFavourite()); 
    mAddressTextView.setText(mPetrolStation.getAddress()); 

    // To start the marquee-effect on the address TextView. 
    mAddressTextView.setSelected(true); 

    LatLng centre = getLocation(); 
    LatLng point = new LatLng(mPetrolStation.getLat(), mPetrolStation.getLon()); 

    if (centre == null) { 
     mDistanceTextView.setText(getResources().getString(R.string.distence_nd)); 
    } else { 
     double distance = computeDistance(centre, point); 
     mDistanceTextView.setText(getResources().getString(R.string.distance_km, distance)); 
    } 

    // TODO: to fix. 
    mCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() { 
     @Override 
     public void onCheckedChanged(CompoundButton compoundButton, boolean isFavourite) { 
      // mPetrolStation.setFavourite(isFavourite); 
     } 
    }); 

    ((SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map)).getMapAsync(new OnMapReadyCallback() { 
     @Override 
     public void onMapReady(GoogleMap googleMap) { 
      mGoogleMap = googleMap; 
      mGoogleMap.getUiSettings().setAllGesturesEnabled(false); 

      double lat = mPetrolStation.getLat(); 
      double lon = mPetrolStation.getLon(); 
      LatLng latLng = new LatLng(lat, lon); 

      mGoogleMap.addMarker(new MarkerOptions().position(latLng)); 

      CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 15); 
      mGoogleMap.moveCamera(cameraUpdate); 
     } 
    }); 

    // Setup Views. 
    mTabLayout = (TabLayout) view.findViewById(R.id.pager_header); 
    mViewPager = (ViewPager) view.findViewById(R.id.pager); 

    // Set an Adapter for the View Pager. 
    TabPagerAdapter tabPagerAdapter = new TabPagerAdapter(getChildFragmentManager()); 
    mViewPager.setAdapter(tabPagerAdapter); 
    mTabLayout.setupWithViewPager(mViewPager); 

    mViewPager.setCurrentItem(SELF_SERVICE_TAB_POSITION); 

    mTabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() { 
     @Override 
     public void onTabSelected(TabLayout.Tab tab) { 
      mViewPager.setCurrentItem(tab.getPosition()); 
     } 

     @Override 
     public void onTabUnselected(TabLayout.Tab tab) { 

     } 

     @Override 
     public void onTabReselected(TabLayout.Tab tab) { 

     } 
    }); 

    return view; 
} 

@Override 
public void onViewCreated(View view, Bundle savedInstanceState) { 
    super.onViewCreated(view, savedInstanceState); 
} 

class TabPagerAdapter extends FragmentPagerAdapter { 

    public TabPagerAdapter(FragmentManager fm) { 
     super(fm); 
    } 

    // Return fragment with respect to position. 
    @Override 
    public Fragment getItem(int position) { 
     Fragment fragment; 

     switch (position) { 

      case SELF_SERVICE_TAB_POSITION: { 
       fragment = SelfServiceFragment.newInstance(mPetrolStationIndex); 

       return fragment; 
      } 

      case FULL_SERVICE_TAB_POSITION: { 
       fragment = FullServiceFragment.newInstance(mPetrolStationIndex); 

       return fragment; 
      } 

     } 

     return null; 
    } 

    @Override 
    public int getCount() { 
     return intItems; 
    } 

    // This method returns the title of the tab according to its position. 
    @Override 
    public CharSequence getPageTitle(int position) { 
     switch (position) { 

      case SELF_SERVICE_TAB_POSITION: { 
       String mSelfService = getResources().getString(R.string.self_service); 

       return mSelfService; 
      } 

      case FULL_SERVICE_TAB_POSITION: { 
       String mFullService = getResources().getString(R.string.full_service); 

       return mFullService; 
      } 

     } 

     return null; 
    } 

} 

} 

Answer 1

解決方案很明顯：我使用的是static TabLayout 和static ViewPager：這是一個錯誤，因爲我的TabPager在另一個ViewPager中。

Answer 2

的片段，你正在創造新的片段我猜。我用片段類似的那種情景，我在tabadapter.the代碼中創建新的片斷實例看起來是這樣的：

公共類TabsPagerAdapter擴展FragmentPagerAdapter {

public TabsPagerAdapter(FragmentManager fm) { 
    super(fm); 
} 

@Override 
public Fragment getItem(int position) { 
    switch (position){ 
     case 0: 
      return new MeFragment(); 
     case 1: 
      return new CommunityFragment(); 
    } 
    return null; 
} 

@Override 
public int getCount() { 
    return 2; 
} 

}

我加入這個mainactivity都看看吧，也許它會幫助：

public class MainActivity extends AppCompatActivity { 

private Toolbar toolbar; 
private TabLayout tabLayout; 
private ViewPager viewPager; 
public static Activity activity; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    activity = this; 
    toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    getSupportActionBar().setDisplayHomeAsUpEnabled(false); 

    viewPager = (ViewPager)findViewById(R.id.viewpager); 
    setupViewPager(viewPager); 

    tabLayout = (TabLayout) findViewById(R.id.tabs); 
    tabLayout.setupWithViewPager(viewPager); 

} 

private void setupViewPager(ViewPager viewPager){ 
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager()); 
    adapter.addFragment(new MeFragment(),"Me"); 
    adapter.addFragment(new CommunityFragment(),"Community"); 
    viewPager.setAdapter(adapter); 
} 

class ViewPagerAdapter extends FragmentPagerAdapter{ 
    private final List<Fragment> mFragmentList = new ArrayList<>(); 
    private final List<String> mFragmentTitleList = new ArrayList<>(); 

    public ViewPagerAdapter(FragmentManager fragmentManager){ 
     super(fragmentManager); 
    } 

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

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

    public void addFragment(Fragment fragment, String title){ 
     mFragmentList.add(fragment); 
     mFragmentTitleList.add(title); 
    } 

    @Override 
    public CharSequence getPageTitle (int position){ 
     return mFragmentTitleList.get(position); 
    } 
} 

}