Fragment Android, Exception ListView NullPointer

Question

Je crée un ListView dans ma classe de fragmentation qui liste simplement les contacts de la base de données de l'application. Je n'ai rien d'extraordinaire depuis que je suis en train de le créer. Pour l'instant, j'obtiens une erreur NullPointer qui ressemble à l'onCreate, mais je ne vois pas l'erreur. peut-être que vous le ferez.

public class ContactsFragment extends ListFragment { 

    Context fContext; 
    private DatabaseHandler db; 
    private SimpleCursorAdapter contactCursorAdapter; 

    public ContactsFragment(){} 
    private View rootView; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     fContext = getActivity(); 
     View rootView = inflater.inflate(R.layout.fragment_contacts, container, false); 

     //Generate ListView from SQLite Database 
     contactListView(); 
     return rootView; 
    } 

    private void contactListView() { 

     DatabaseHandler db = new DatabaseHandler(fContext); 
     Cursor contactCursor = db.fetchContacts(); 

     // Allow activity to manage the lifetime of the cursor 
     //startManagingCursor(contactCursor); 

     //Setup mapping of cursor 
     String[] fromFields = new String[] 
       {db.KEY_NAMECONCAT, 
       db.KEY_COMPANY}; 
     int[] toViewIds = new int[] 
       {R.id.tvFullName, 
       R.id.tvContactCompany}; 

     //Create Adapter 
     @SuppressWarnings("deprecation") 
     SimpleCursorAdapter contactCursorAdapter = new SimpleCursorAdapter(
       fContext, 
       R.layout.contact_list_item, 
       contactCursor, 
       fromFields, 
       toViewIds 
       ); 

     //Set the adapter for the List View 
     ListView contactList = (ListView) rootView.findViewById(R.id.listContacts); 
     contactList.setAdapter(contactCursorAdapter); 

    } 

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

    @Override 
    public void onDestroy() { 
     super.onDestroy(); 
     db.close(); 
    } 

} 

fragment_contacts.xml

<?xml version="1.0" encoding="utf-8"?> 
<ListView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/listContacts" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" > 

</ListView> 

contact_list_item.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="?android:attr/listPreferredItemHeight" 
    android:padding="6dip" > 

    <TextView 
     android:id="@+id/tvFullName" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:paddingLeft="10dp" 
     android:text="FullName" 
     android:textSize="18sp" /> 

    <TextView 
     android:id="@+id/tvContactCompany" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignLeft="@+id/tvFullName" 
     android:layout_below="@+id/tvFullName" 
     android:paddingLeft="10dp" 
     android:text="Company" /> 

</RelativeLayout> 

Logcat:

FATAL EXCEPTION: main 
    Process: com.garudaapps.myapp, PID: 30894 
    java.lang.NullPointerException 
    at com.garudaapps.myapp.ContactsFragment.contactListView(ContactsFragment.java:89) 
    at com.garudaapps.myapp.ContactsFragment.onCreateView(ContactsFragment.java:35) 
    at android.app.Fragment.performCreateView(Fragment.java:1700) 
    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890) 
    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062) 
    at android.app.BackStackRecord.run(BackStackRecord.java:684) 
    at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447) 
    at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443) 
    at android.os.Handler.handleCallback(Handler.java:733) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:157) 
    at android.app.ActivityThread.main(ActivityThread.java:5356) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081) 
    at dalvik.system.NativeStart.main(Native Method) 

Answer 1

Essayez cette façon, espérons que cela vous aidera à résoudre votre problème .

Vous avez initialiser la référence de liste au mauvais endroit.

public class ContactsFragment extends ListFragment { 

    Context fContext; 
    private DatabaseHandler db; 
    private SimpleCursorAdapter dataAdapter; 

    public ContactsFragment(){} 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     fContext = getActivity(); 
     View rootView = inflater.inflate(R.layout.fragment_contacts, container, false); 

     //Generate ListView from SQLite Database 
     ListView contactList = (ListView) rootView.findViewById(R.id.listContacts); 
     contactListView(); 
     contactList.setAdapter(contactCursorAdapter); 
     return rootView; 
    } 

    private void contactListView() { 

     DatabaseHandler db = new DatabaseHandler(fContext); 
     Cursor contactCursor = db.fetchContacts(); 

     // Allow activity to manage the lifetime of the cursor 
     //startManagingCursor(contactCursor); 

     //Setup mapping of cursor 
     String[] fromFields = new String[] 
       {db.KEY_NAMECONCAT, 
         db.KEY_COMPANY}; 
     int[] toViewIds = new int[] 
       {R.id.tvFullName, 
         R.id.tvContactCompany}; 

     //Create Adapter 
     @SuppressWarnings("deprecation") 
     SimpleCursorAdapter contactCursorAdapter = new SimpleCursorAdapter(
       fContext, 
       R.layout.contact_list_item, 
       contactCursor, 
       fromFields, 
       toViewIds 
     ); 

    } 

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

    @Override 
    public void onDestroy() { 
     super.onDestroy(); 
     db.close(); 
    } 

}