Hata Android Studio'larda ComponentInfo NullPointerException etkinliği başlatılamadı

Question

Uygulamamı çalıştırmaya çalışıyorum, ancak "Randevuları Yönet" sayfasına yönlendirmek için düğmeye her bastığımda, uygulama çöküyor.

ManageAppointments.java AppAddFragment.java

public class AppListFrag extends Fragment implements AdapterView.OnItemClickListener, AdapterView.OnItemLongClickListener { 
public static final String ARG_ITEM_ID = "appointment_list"; 

Activity activity; 
ListView appListView; 
ArrayList<Appointment> appointments; 

AppListAdapter appListAdapter; 
AppointmentDAO appointmentDAO; 

private GetAppointmentTask task; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    activity = getActivity(); 
    appointmentDAO = new AppointmentDAO(activity); 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
    View view = inflater.inflate(R.layout.frag_app_list, container, false); 
    findViewsById(view); 

    task = new GetAppointmentTask(activity); 
    task.execute((Void) null); 

    appListView.setOnItemClickListener(this); 
    appListView.setOnItemLongClickListener(this); 
    return view; 
} 

private void findViewsById(View view) { 
    appListView = (ListView) view.findViewById(R.id.list); 
} 

@Override 
public void onResume() { 
    getActivity().setTitle(R.string.app_name); 
    getActivity().getActionBar().setTitle(R.string.app_name); 
    super.onResume(); 
} 

@Override 
public void onItemClick(AdapterView<?> list, View arg1, int position, long arg3) { 
    Appointment appointment = (Appointment) list.getItemAtPosition(position); 

    if (appointment != null) { 
     Bundle arguments = new Bundle(); 
     arguments.putParcelable("selectedAppointment", appointment); 
     CustomAppDialogFragment customAppDialogFragment = new CustomAppDialogFragment(); 
     customAppDialogFragment.setArguments(arguments); 
     customAppDialogFragment.show(getFragmentManager(), CustomAppDialogFragment.ARG_ITEM_ID); 
    } 
} 

@Override 
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long arg3) { 
    Appointment appointment = (Appointment) parent.getItemAtPosition(position); 

    // Use AsyncTask to delete from database 
    appointmentDAO.delete(appointment); 
    appListAdapter.remove(appointment); 
    return true; 
} 

public class GetAppointmentTask extends AsyncTask<Void, Void, ArrayList<Appointment>> { 

    private final WeakReference<Activity> activityWeakRef; 

    public GetAppointmentTask(Activity context) { 
     this.activityWeakRef = new WeakReference<Activity>(context); 
    } 

    @Override 
    protected ArrayList<Appointment> doInBackground(Void... arg0) { 
     ArrayList<Appointment> appointmentList = appointmentDAO.getAppointments(); 
     return appointmentList; 
    } 

    @Override 
    protected void onPostExecute(ArrayList<Appointment> appList) { 
     if (activityWeakRef.get() != null && !activityWeakRef.get().isFinishing()) { 
      Log.d("appointments", appList.toString()); 
      appointments = appList; 
      if (appList != null) { 
       if (appList.size() != 0) { 
        appListAdapter = new AppListAdapter(activity, appList); 
        appListView.setAdapter(appListAdapter); 
       } else { 
        Toast.makeText(activity, "No Appointments", Toast.LENGTH_LONG).show(); 
       } 
      } 

     } 
    } 
} 

/* 
* This method is invoked from MainActivity onFinishDialog() method. It is 
* called from CustomPatientDialogFragment when an patient record is updated. 
* This is used for communicating between fragments. 
*/ 
public void updateView() { 
    task = new GetAppointmentTask(activity); 
    task.execute((Void) null); 
} 

}

public class ManageAppointments extends FragmentActivity implements AppDialogFragmentListener { 
private Fragment contentFragment; 
private AppListFrag appListFragment; 
private AppAddFrag appAddFragment; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.manage_appointments); 
    java.text.DateFormat formatter = android.text.format.DateFormat.getDateFormat(getApplicationContext()); 
    FragmentManager fragmentManager = getSupportFragmentManager(); 

    /* 
    * This is called when orientation is changed. 
    */ 
    if (savedInstanceState != null) { 
     if (savedInstanceState.containsKey("content")) { 
      String content = savedInstanceState.getString("content"); 
      if (content.equals(AppAddFrag.ARG_ITEM_ID)) { 
       if (fragmentManager.findFragmentByTag(AppAddFrag.ARG_ITEM_ID) != null) { 
        setFragmentTitle(R.string.add_appointment); 
        contentFragment = fragmentManager.findFragmentByTag(AppAddFrag.ARG_ITEM_ID); 
       } 
      } 
     } 
     if (fragmentManager.findFragmentByTag(AppListFrag.ARG_ITEM_ID) != null) { 
      appListFragment = (AppListFrag) fragmentManager.findFragmentByTag(AppListFrag.ARG_ITEM_ID); 
      contentFragment = appListFragment; 
     } 
    } else { 
     appListFragment = new AppListFrag(); 
     setFragmentTitle(R.string.app_name); 
     switchContent(appListFragment, AppListFrag.ARG_ITEM_ID); 
    } 
} 

@Override 
protected void onSaveInstanceState(Bundle outState) { 
    if (contentFragment instanceof AppAddFrag) { 
     outState.putString("content", AppAddFrag.ARG_ITEM_ID); 
    } else { 
     outState.putString("content", AppListFrag.ARG_ITEM_ID); 
    } 
    super.onSaveInstanceState(outState); 
} 

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

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    switch (item.getItemId()) { 
     case R.id.action_add: 
      setFragmentTitle(R.string.add_appointment); 
      appAddFragment = new AppAddFrag(); 
      switchContent(appAddFragment, AppAddFrag.ARG_ITEM_ID); 

      return true; 
    } 
    return super.onOptionsItemSelected(item); 
} 

/* 
* We consider PatientListFragment as the home fragment and it is not added to 
* the back stack. 
*/ 
public void switchContent(Fragment fragment, String tag) { 
    FragmentManager fragmentManager = getSupportFragmentManager(); 
    while (fragmentManager.popBackStackImmediate()) 
     ; 

    if (fragment != null) { 
     FragmentTransaction transaction = fragmentManager 
       .beginTransaction(); 
     transaction.replace(R.id.content_frame, fragment, tag); 
     // Only PatientAddFragment is added to the back stack. 
     if (!(fragment instanceof AppListFrag)) { 
      transaction.addToBackStack(tag); 
     } 
     transaction.commit(); 
     contentFragment = fragment; 
    } 
} 

protected void setFragmentTitle(int resourseId) { 
    setTitle(resourseId); 
    getActionBar().setTitle(resourseId); 

} 

/* 
* We call super.onBackPressed(); when the stack entry count is > 0. if it 
* is instanceof PatientListFragment or if the stack entry count is == 0, then 
* we prompt the user whether to quit the app or not by displaying dialog. 
* In other words, from PatientListFragment on back press it quits the app. 
*/ 
@Override 
public void onBackPressed() { 
    FragmentManager fm = getSupportFragmentManager(); 
    if (fm.getBackStackEntryCount() > 0) { 
     super.onBackPressed(); 
    } else if (contentFragment instanceof AppListFrag 
      || fm.getBackStackEntryCount() == 0) { 
     //Shows an alert dialog on quit 
     onShowQuitDialog(); 
    } 
} 

public void onShowQuitDialog() { 
    AlertDialog.Builder builder = new AlertDialog.Builder(this); 
    builder.setCancelable(false); 

    builder.setMessage("Do You Want To Quit?"); 
    builder.setPositiveButton(android.R.string.yes, 
      new DialogInterface.OnClickListener() { 
       @Override 
       public void onClick(DialogInterface dialog, int id) { 
        finish(); 
       } 
      }); 
    builder.setNegativeButton(android.R.string.no, 
      new DialogInterface.OnClickListener() { 
       public void onClick(DialogInterface dialog, int id) { 
        dialog.cancel(); 
       } 
      }); 
    builder.create().show(); 
} 

@Override 
public void onFinishDialog() { 
    if (appListFragment != null) { 
     appListFragment.updateView(); 
    } 
} 

}

AppListFragment.java: İşte aşağıda benim kodudur

}

Hata mesajı:

04-11 19:02:12.608 25872-25872/? E/AndroidRuntime: FATAL EXCEPTION: main 
                Process: com.xpresspatients.fyp, PID: 25872 
                java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xpresspatients.fyp/com.xpresspatients.fyp.ManageAppointments}: java.lang.NullPointerException 
                 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2237) 
                 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2286) 
                 at android.app.ActivityThread.access$800(ActivityThread.java:145) 
                 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1243) 
                 at android.os.Handler.dispatchMessage(Handler.java:102) 
                 at android.os.Looper.loop(Looper.java:136) 
                 at android.app.ActivityThread.main(ActivityThread.java:5127) 
                 at java.lang.reflect.Method.invokeNative(Native Method) 
                 at java.lang.reflect.Method.invoke(Method.java:515) 
                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:825) 
                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641) 
                 at dalvik.system.NativeStart.main(Native Method) 
                Caused by: java.lang.NullPointerException 
                 at com.xpresspatients.fyp.ManageAppointments.setFragmentTitle(ManageAppointments.java:108) 
                 at com.xpresspatients.fyp.ManageAppointments.onCreate(ManageAppointments.java:50) 
                 at android.app.Activity.performCreate(Activity.java:5231) 
                 at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
                 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2201) 
                 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2286)  
                 at android.app.ActivityThread.access$800(ActivityThread.java:145)  
                 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1243)  
                 at android.os.Handler.dispatchMessage(Handler.java:102)  
                 at android.os.Looper.loop(Looper.java:136)  
                 at android.app.ActivityThread.main(ActivityThread.java:5127)  
                 at java.lang.reflect.Method.invokeNative(Native Method)  
                 at java.lang.reflect.Method.invoke(Method.java:515)  

Ben benzer sorular baktım ve buna göre değişiklik yapmadan çalıştı, ancak yine de bu hatayı almaya devam ettik. Lütfen yardım et. Şimdiden teşekkürler.

Answer 1

setFragmentTitle(), getActionBar() işlevinizde görünüyor. ActionBar var gibi görünmüyor. SupportActionBar kullanıyor musunuz? Bu deneyin:

protected void setFragmentTitle(int resourseId) { 
    if (getSupportActionBar() != null) { 
     getSupportActionBar().setTitle(getString(resourseId)); 
    } 
}