Android boş bir nesne referans Burada

Question

ilgili 'boşluk android.support.v4.app.Fragment.setMenuVisibility (boolean)' sanal bir yöntem çağırmak için girişimi hatanın tam yığın izidir JSON beslemelerini vermek istediğim için projedeki parçaları kullanmaya başladıktan sonra görünmek için. Ben Tabs oluşturma zaman önce ince, NavigationDrawer vb

MainActivity.java

genel sınıf MainActivity ActionBarActivity MaterialTabListener uygular uzatır {

private Toolbar mToolbar; 
private NavigationDrawerFragment mDrawerFragment; 
private DrawerLayout mDrawerLayout; 

private MaterialTabHost mTabHost; 
private ViewPager mViewPager; 

public static final int SERVICES_ALL = 1; 
public static final int SERVICES_FEATURED = 2; 
public static final int SERVICES_NEW = 3; 

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

    mToolbar = (Toolbar) findViewById(R.id.app_bar); 
    setSupportActionBar(mToolbar); 
    getSupportActionBar().setDisplayShowHomeEnabled(true); 

    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 
    mDrawerFragment = (NavigationDrawerFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer); 
    mDrawerFragment.setUp(R.id.fragment_navigation_drawer, mDrawerLayout, mToolbar); 

    mTabHost = (MaterialTabHost) findViewById(R.id.materialTabHost); 
    mViewPager = (ViewPager) findViewById(R.id.viewPager); 

    MyPagerAdapter adapter = new MyPagerAdapter(getSupportFragmentManager()); 
    mViewPager.setAdapter(adapter); 
    mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener(){ 
     @Override 
     public void onPageSelected(int position) { 
      mTabHost.setSelectedNavigationItem(position); 
     } 
    }); 

    for(int i=0; i<adapter.getCount(); i++){ 
     mTabHost.addTab(
       mTabHost.newTab(). 
         setText(adapter.getPageTitle(i)). 
         setTabListener(this) 
     ); 
    } 
} 

@Override 
public void onTabSelected(MaterialTab materialTab) { 
    mViewPager.setCurrentItem(materialTab.getPosition()); 
} 

@Override 
public void onTabReselected(MaterialTab materialTab) { 

} 

@Override 
public void onTabUnselected(MaterialTab materialTab) { 

} 

private class MyPagerAdapter extends FragmentStatePagerAdapter{ 
    FragmentManager fragmentManager; 

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

    @Override 
    public Fragment getItem(int num) { 
     Fragment fragment = null; 
     switch (num){ 
      case SERVICES_ALL: 
       fragment = FragmentAll.newInstance("",""); 
       break; 
      case SERVICES_FEATURED: 
       fragment = FragmentFeatured.newInstance("",""); 
       break; 
      case SERVICES_NEW: 
       fragment = FragmentNew.newInstance("",""); 
       break; 
     } 
     return fragment; 
    } 

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

    public CharSequence getPageTitle(int position){ 
     return getResources().getStringArray(R.array.tabs)[position]; 
    } 
} 

@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) { 
     Toast.makeText(this, "Hey you just hit " + item.getTitle(), Toast.LENGTH_LONG).show(); 
     return true; 
    } 

    if (id == R.id.action_next) { 
     startActivity(new Intent(this, DetailActivity.class)); 
    } 

    return super.onOptionsItemSelected(item); 
} 

}

FragmentAll.java (Diğer 2 fragman FragmentAll'a benzer.)

genel sınıf FragmentAll Fragment uzanır {

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

private String mParam1; 
private String mParam2; 

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

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

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

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    // Inflate the layout for this fragment 
    return inflater.inflate(R.layout.fragment_all, container, false); 
} 
} 

StackTrace:

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:836) 
      at android.support.v4.view.ViewPager.populate(ViewPager.java:986) 
      at android.support.v4.view.ViewPager.populate(ViewPager.java:918) 
      at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1440) 
      at android.view.View.measure(View.java:17430) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
      at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436) 
      at android.widget.LinearLayout.measureVertical(LinearLayout.java:722) 
      at android.widget.LinearLayout.onMeasure(LinearLayout.java:613) 
      at android.view.View.measure(View.java:17430) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
      at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124) 
      at android.view.View.measure(View.java:17430) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
      at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436) 
      at android.widget.LinearLayout.measureVertical(LinearLayout.java:722) 
      at android.widget.LinearLayout.onMeasure(LinearLayout.java:613) 
      at android.view.View.measure(View.java:17430) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
      at android.view.View.measure(View.java:17430) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
      at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436) 
      at android.widget.LinearLayout.measureVertical(LinearLayout.java:722) 
      at android.widget.LinearLayout.onMeasure(LinearLayout.java:613) 
      at android.view.View.measure(View.java:17430) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
      at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2560) 
      at android.view.View.measure(View.java:17430) 
      at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2001) 
      at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1166) 
      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1372) 
      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1054) 
      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5779) 
      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767) 
      at android.view.Choreographer.doCallbacks(Choreographer.java:580) 
      at android.view.Choreographer.doFrame(Choreographer.java:550) 
      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5221) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 

Answer 1

public static final int SERVICES_ALL = 1; 
public static final int SERVICES_FEATURED = 2; 
public static final int SERVICES_NEW = 3; 

public static final int SERVICES_ALL = 0; 
public static final int SERVICES_FEATURED = 1; 
public static final int SERVICES_NEW = 2; 

getItem olmalıdır içinde olduğu anlamına gelir 0 tabanlı-indeksi, bir Kodunuz, Bağdaştırıcınızın case 0 hiçbir zaman bir ile eşleşmez ve bu durumda, bir istisnai duruma neden olan boş bir parça döndürüyorsunuz