getAktivite geri dönen bölüm sıfırdan

Question

Okul için bir android uygulaması yapıyorum. Bu uygulama için bir veritabanından sadece dizeleri ile bir gridview gösteren bir parçam var. Bunun için bir parçaya ihtiyacım var. GetActivity() öğesini çağırdığımda, null değerini döndürür. here önerildiği gibi onAttach yöntemi, uygulama çökmeden önce çağrılmaz. Bunu nasıl çözmeliyim?
weekFragmetn.xml:

package nl.siebeh.schoolmate; 

import java.util.ArrayList; 

import android.app.Activity; 
import android.content.Context; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.util.Log; 
import android.view.ContextMenu; 
import android.view.ContextMenu.ContextMenuInfo; 
import android.view.LayoutInflater; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.GridView; 

public class weekFragment extends Fragment { 
    dbLayer db; 
    Context mContext; 

    @Override 
    public void onAttach(Activity activity) { 
     mContext = getActivity(); 
     Log.i("Schoolmate","onAttach called"); 
     super.onAttach(activity); 
    } 

    public weekFragment newInstance(String title) { 
     Log.i("Schoolmate","newInstance called"); 
     db = new dbLayer(mContext); 
     weekFragment fragment = new weekFragment(); 
     ArrayList<ArrayList<Object>> result = null; 

     if(title == "leraren"){ 
      result = db.getAllRowsAsArrays("weekTeacher", null); 
     }else if(title == "locatie"){ 
      result = db.getAllRowsAsArrays("weekLocation", null); 
     }else if(title == "vakken"){ 
      result = db.getAllRowsAsArrays("weekSubjects", null); 
     } 

     String[] array = new String[60]; 

     for(int i = 0; i < 60; i++){ 
      array[i] = ""; 
     } 

     array[1] = getResources().getStringArray(R.array.days)[0]; 
     array[2] = getResources().getStringArray(R.array.days)[1]; 
     array[3] = getResources().getStringArray(R.array.days)[2]; 
     array[4] = getResources().getStringArray(R.array.days)[3]; 
     array[5] = getResources().getStringArray(R.array.days)[4]; 

     for(int i = 1; i < 10; i++){ 
      array[i] = Integer.toString(i); 
     } 

     for(int position = 0; position < result.size(); position++){ 
      ArrayList<Object> row = result.get(position); 
      int hour = Integer.valueOf(row.get(1).toString()).intValue(); 
      int day = Integer.valueOf(row.get(0).toString()).intValue(); 
      int pos = 6 * hour + day; 
      array[pos] = row.get(position).toString(); 
     } 
     fragment.mContent = array; 

     return fragment; 
    } 

    private String[] mContent = {""}; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     if (container == null) { 
      return null; 
     } 
     View v = inflater.inflate(R.layout.week_fragment, container, false); 
     GridView gridview = (GridView) v.findViewById(R.id.gridview); 
     gridview.setAdapter(new weekAdapter(mContext, mContent)); 
     return gridview; 
    } 

    @Override 
    public boolean onContextItemSelected(MenuItem item) { 
     return super.onContextItemSelected(item); 
    } 

    @Override 
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { 
     super.onCreateContextMenu(menu, v, menuInfo); 
    } 



} 

logcat: (öğe üzerinde tıklama beri fragmanı/başlatılmış gömülü olduğu aktiviteyi başlatır bir listede öğe)

09-29 19:10:56.611: INFO/ActivityManager(70): Starting: Intent { cmp=nl.siebeh.schoolmate/.overviewWeek } from pid 536 
09-29 19:10:56.970: INFO/Schoolmate(536): newInstance called 
09-29 19:11:06.631: WARN/ActivityManager(70): Launch timeout has expired, giving up wake lock! 
09-29 19:11:06.671: WARN/ActivityManager(70): Activity idle timeout for HistoryRecord{40770188 nl.siebeh.schoolmate/.overviewWeek} 
09-29 19:12:20.661: DEBUG/SntpClient(70): request time failed: java.net.SocketException: Address family not supported by protocol 
09-29 19:14:11.811: DEBUG/dalvikvm(536): Debugger has detached; object registry had 413 entries 
09-29 19:14:11.811: ERROR/SchoolMate(536): java.lang.NullPointerException 
09-29 19:14:11.811: INFO/SchoolMate(536): Context is null 
09-29 19:14:11.820: WARN/System.err(536): java.lang.NullPointerException 
09-29 19:14:11.820: WARN/System.err(536):  at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:118) 
09-29 19:14:11.820: WARN/System.err(536):  at nl.siebeh.schoolmate.dbLayer.<init>(dbLayer.java:50) 
09-29 19:14:11.820: WARN/System.err(536):  at nl.siebeh.schoolmate.weekFragment.newInstance(weekFragment.java:31) 
09-29 19:14:11.820: WARN/System.err(536):  at nl.siebeh.schoolmate.fragmentAdapter.getItem(fragmentAdaptar.java:21) 
09-29 19:14:11.820: WARN/System.err(536):  at nl.siebeh.schoolmate.titleFragmentAdapter.getItem(titleFragmentAdapter.java:1) 
09-29 19:14:11.820: WARN/System.err(536):  at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:62) 
09-29 19:14:11.820: WARN/System.err(536):  at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:321) 
09-29 19:14:11.820: WARN/System.err(536):  at android.support.v4.view.ViewPager.populate(ViewPager.java:441) 
09-29 19:14:11.820: WARN/System.err(536):  at android.support.v4.view.ViewPager.onAttachedToWindow(ViewPager.java:563) 
09-29 19:14:11.820: WARN/System.err(536):  at android.view.View.dispatchAttachedToWindow(View.java:6156) 
09-29 19:14:11.820: WARN/System.err(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1122) 
09-29 19:14:11.820: WARN/System.err(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1127) 
09-29 19:14:11.820: WARN/System.err(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1127) 
09-29 19:14:11.820: WARN/System.err(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1127) 
09-29 19:14:11.820: WARN/System.err(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1127) 
09-29 19:14:11.820: WARN/System.err(536):  at android.view.ViewRoot.performTraversals(ViewRoot.java:765) 
09-29 19:14:11.830: WARN/System.err(536):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1859) 
09-29 19:14:11.840: WARN/System.err(536):  at android.os.Handler.dispatchMessage(Handler.java:99) 
09-29 19:14:11.840: WARN/System.err(536):  at android.os.Looper.loop(Looper.java:123) 
09-29 19:14:11.840: WARN/System.err(536):  at android.app.ActivityThread.main(ActivityThread.java:3683) 
09-29 19:14:11.840: WARN/System.err(536):  at java.lang.reflect.Method.invokeNative(Native Method) 
09-29 19:14:11.840: WARN/System.err(536):  at java.lang.reflect.Method.invoke(Method.java:507) 
09-29 19:14:11.850: WARN/System.err(536):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
09-29 19:14:11.850: WARN/System.err(536):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
09-29 19:14:11.850: WARN/System.err(536):  at dalvik.system.NativeStart.main(Native Method) 
09-29 19:14:11.850: DEBUG/AndroidRuntime(536): Shutting down VM 
09-29 19:14:11.850: WARN/dalvikvm(536): threadid=1: thread exiting with uncaught exception (group=0x40015560) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536): FATAL EXCEPTION: main 
09-29 19:14:11.870: ERROR/AndroidRuntime(536): java.lang.NullPointerException 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at nl.siebeh.schoolmate.weekFragment.newInstance(weekFragment.java:49) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at nl.siebeh.schoolmate.fragmentAdapter.getItem(fragmentAdaptar.java:21) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at nl.siebeh.schoolmate.titleFragmentAdapter.getItem(titleFragmentAdapter.java:1) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:62) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:321) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.support.v4.view.ViewPager.populate(ViewPager.java:441) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.support.v4.view.ViewPager.onAttachedToWindow(ViewPager.java:563) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.view.View.dispatchAttachedToWindow(View.java:6156) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1122) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1127) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1127) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1127) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1127) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.view.ViewRoot.performTraversals(ViewRoot.java:765) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1859) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.os.Handler.dispatchMessage(Handler.java:99) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.os.Looper.loop(Looper.java:123) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at android.app.ActivityThread.main(ActivityThread.java:3683) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at java.lang.reflect.Method.invokeNative(Native Method) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at java.lang.reflect.Method.invoke(Method.java:507) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
09-29 19:14:11.870: ERROR/AndroidRuntime(536):  at dalvik.system.NativeStart.main(Native Method) 
09-29 19:14:11.890: WARN/ActivityManager(70): Force finishing activity nl.siebeh.schoolmate/.overviewWeek 
09-29 19:14:12.413: WARN/ActivityManager(70): Activity pause timeout for HistoryRecord{40770188 nl.siebeh.schoolmate/.overviewWeek} 
09-29 19:14:21.910: WARN/ActivityManager(70): Launch timeout has expired, giving up wake lock! 
09-29 19:14:22.441: WARN/ActivityManager(70): Activity idle timeout for HistoryRecord{4070c7a0 nl.siebeh.schoolmate/.schoolmate} 
09-29 19:14:32.451: WARN/ActivityManager(70): Activity destroy timeout for HistoryRecord{40770188 nl.siebeh.schoolmate/.overviewWeek} 

Answer 1

Değilsin numaralı telefondan, numaralı telefonu arayarak getActivity() numaralı telefonu arayınız.

Bir NullPointerException alıyorsunuz, çünkü mContextnull. Tahminim, null kodunun koduna göre new weekFragment() numaralı telefonu arayarak newInstance() numaralı telefonu çağırıyor. Muhtemelen, Fragment JavaDocs'da özetlenen bazı kalıpları izlediğinizi düşündünüz, fakat burada, newInstance() bir static yöntemidir, burada sahip olduğunuz gibi bir örnek yöntemi değildir.

Kodun tamamını newInstance()'dan alın ve onActivityCreated()'a taşıyın ya da parçanın etkinliğe eklendiği bir zamanda getActivity() çalışır. Yol boyunca, onAttach() uygulamanızı ve mContext veri üyenizi silin, bunların ikisi de gereklidir (ve mContext çok korkutucu bir şekilde doldurulur).