geçersiz android.support.v4.app.Fragment.setMenuVisibility ben projenin burada</p> <p>konusu parçaları kullanmaya başladıktan sonra

Question

hata yalnızca görünmeye başladı Boş bir nesne başvurusu üzerine (boolean)' ..

benim kodudur

public class MainActivity extends AppCompatActivity { 

private Toolbar toolbar; 
private ViewPager mPager; 
private SlidingTabLayout mTabs; 
private MyPagerAdapter adapter; 

public static final int product_result = 0; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    toolbar = (Toolbar) findViewById(R.id.app_bar); 

    setSupportActionBar(toolbar); 
    assert getSupportActionBar() != null; 
    getSupportActionBar().setDisplayShowHomeEnabled(true); 

    NavigationDrawerFragment navigationDrawerFragment = (NavigationDrawerFragment) 
      getSupportFragmentManager().findFragmentById(R.id.fragment_nav_drawer); 
    navigationDrawerFragment.setUp(R.id.fragment_nav_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar); 

    mPager = (ViewPager) findViewById(R.id.pager); 
    adapter = new MyPagerAdapter(getSupportFragmentManager()); 
    mPager.setAdapter(adapter); 

    mTabs = (SlidingTabLayout) findViewById(R.id.tabs); 
    mTabs.setDistributeEvenly(true); 
    mTabs.setCustomTabView(R.layout.custom_tab_view, R.id.tabText); 
    int bgColor = ContextCompat.getColor(this, R.color.colorPrimary); 
    mTabs.setBackgroundColor(bgColor); 
    mTabs.setSelectedIndicatorColors(ContextCompat.getColor(MainActivity.this, R.color.colorAccent)); 
    mTabs.invalidate(); 
    mTabs.setViewPager(mPager); 
} 


@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    getMenuInflater().inflate(R.menu.menu_main, menu); 
    return true; 
} 

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    int id = item.getItemId(); 
    if (id == R.id.action_settings) { 

     return true; 
    } 
    if (id == R.id.navigate) { 
     startActivity(new Intent(this, SubActivity.class)); 
    } 
    if (id == R.id.TabActivity) { 
     startActivity(new Intent(this, ActivityUsingTabLibrary.class)); 
    } 
    if (id == R.id.VectorTest) { 
     startActivity(new Intent(this, VectorTestActivity.class)); 
    } 
    return super.onOptionsItemSelected(item); 
} 


class MyPagerAdapter extends FragmentStatePagerAdapter { 
    int icons[] = {R.drawable.home, R.drawable.hot_article, R.drawable.dizzy_person}; 

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

    @Override 
    public Fragment getItem(int position) { 

     Fragment fragment = null; 
     switch(position){ 
      case product_result: 
       fragment = FragmentProduct.newInstance("",""); 
       break; 
     } 
     return fragment; 
    } 

    @Override 
    public CharSequence getPageTitle(int position) { 
     Drawable drawable = ResourcesCompat.getDrawable(getResources(), icons[position], null); 
     drawable.setBounds(0, 0, 36, 36); 
     ImageSpan imageSpan = new ImageSpan(drawable); 
     SpannableString spannableString = new SpannableString(" "); 
     spannableString.setSpan(imageSpan, 0, spannableString.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE); 
     return spannableString; 
    } 

    @Override 
    public int getCount() { 
     return 3; 
    } 
} 

}

bu benim fragment.class im geçen JSONObject nesnesi tost olduğunu. Ben de bu link bu aynı sorunu görmüş ve ben onun çözümünü uygulamak ama alışkanlık benim için çalışmak

02-29 12:10:01.047 17100-17100/com.mydesign.rockstar.materialdesignexample E/AndroidRuntime: FATAL EXCEPTION: main 
Process: com.mydesign.rockstar.materialdesignexample, PID: 17100 
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.Fragment.setMenuVisibility(boolean)' on a null object reference 
    at android.support.v4.app.FragmentStatePagerAdapter.instantiateItem(FragmentStatePagerAdapter.java:116) 
    at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:870) 
    at android.support.v4.view.ViewPager.populate(ViewPager.java:1086) 
    at android.support.v4.view.ViewPager.populate(ViewPager.java:952) 
    at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474) 
    at android.view.View.measure(View.java:18804) 
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:901) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:630) 
    at android.view.View.measure(View.java:18804) 
    at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:940) 
    at android.view.View.measure(View.java:18804) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954) 
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:194) 
    at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135) 
    at android.view.View.measure(View.java:18804) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954) 
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465) 
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:748) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:630) 
    at android.view.View.measure(View.java:18804) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954) 
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:194) 
    at android.view.View.measure(View.java:18804) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954) 
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465) 
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:748) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:630) 
    at android.view.View.measure(View.java:18804) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954) 
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:194) 
    at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2643) 
    at android.view.View.measure(View.java:18804) 
    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2112) 
    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1228) 
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1464) 
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1119) 
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6060) 
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858) 
    at android.view.Choreographer.doCallbacks(Choreographer.java:670) 
    at android.view.Choreographer.doFrame(Choreographer.java:606) 
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844) 
    at android.os.Handler.handleCallback(Handler.java:746) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5443) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 

public class FragmentProduct extends Fragment { 

public static final String product_url = "http://oasisgroups.com/oApp/product.php"; 

private static final String ARG_PARAM1 = "param1"; 
private static final String ARG_PARAM2 = "param2"; 

private String mParam1; 
private String mParam2; 
private VolleySingleton volleySingleton; 
private ImageLoader imageLoader; 
private RequestQueue requestQueue; 

public FragmentProduct() { 
    // Required empty public constructor 
} 

public static FragmentProduct newInstance(String param1, String param2) { 
    FragmentProduct fragment = new FragmentProduct(); 
    Bundle args = new Bundle(); 
    args.putString(ARG_PARAM1, param1); 
    args.putString(ARG_PARAM2, param2); 
    fragment.setArguments(args); 
    return fragment; 
} 

public static String getRequestUrl(int limit) { 
    return product_url + "&limit=" + limit; 
} 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    if (getArguments() != null) { 
     mParam1 = getArguments().getString(ARG_PARAM1); 
     mParam2 = getArguments().getString(ARG_PARAM2); 
    } 

    volleySingleton = VolleySingleton.getInstance(); 
    requestQueue = volleySingleton.getmRequestQueue(); 
    JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, getRequestUrl(10), 
      new Response.Listener<JSONObject>() { 
       @Override 
       public void onResponse(JSONObject response) { 
        L.t(getActivity(), response.toString()); 
       } 
      }, new Response.ErrorListener() { 
     @Override 
     public void onErrorResponse(VolleyError error) { 

     } 
    }); 
    requestQueue.add(request); 

} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    return inflater.inflate(R.layout.fragment_product, container, false); 
} 

}

stackTrace .. ben hala sıkıştım, yardım et. kodumu kontrol et ve neyi kaçırdığımı göster.

Answer 1

oh evet .. sonunda hatamı buldum .. her şeyden önce kodumda bir hata yok. her şey yolunda.

Üç sekme düzenim var ve sadece bir tablayout için geçiyorum ve diğer ikisi boş alıyor, bu yüzden üç anahtar durum bildirimi uygulamak zorundayım.

public Fragment getItem(int position) { 

    Fragment fragment = null; 
    switch(position){ 
     case product_result: 
      fragment = FragmentProduct.newInstance("",""); 
      break; 
    } 
    return fragment; 
} 

yerine

public Fragment getItem(int num) { 
     Fragment fragment = null; 
     switch (num) { 
      case TAB_PRODUCT_RESULT: 
       fragment = FragmentProduct.newInstance("", ""); 
       break; 
      case TAB_SECOND: 
       fragment = MyFragment.getInstance(num); 
       break; 
      case TAB_THIRD: 
       fragment = MyFragment.getInstance(num); 
       break; 
     } 
     return fragment; 
    } 

thats ..

Answer 2

Sorun, MyPagerAdapter ürününüzün public Fragment getItem(int position) yönteminde olduğunu düşünüyorum. Aşağıdaki kod parçacığınız null parçalarını döndürüyor. product_result0 için başlatılır çünkü

Fragment fragment = null; 
switch(position){ 
    case product_result: 
     fragment = FragmentProduct.newInstance("",""); 
     break; 
    } 
return fragment; 

Yalnızca, pozisyon 0 için gerçek parçasını olsun. Diğer tüm durumlarda, null döndürür. NULL olmayan bir parça örneğini her zaman döndürmek için yukarıdaki kod parçacığını değiştirin.