Calling snippet from activity throws null-pointer-android-exception
I'm trying to call a list fragment from a fragment activity, I get a null pointer exception. Here is my code,
public class SampleEvents extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sample_events);
FragmentManager fm = getFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.fragment_content);
if (fragment == null) {
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.fragment_content, new EventsList());
ft.commit();
}
}
Fragment action layout
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<FrameLayout
android:id="@+id/fragment_content"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</LinearLayout>
Event_list snippet layout
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/background"
android:orientation="vertical" >
<TextView
android:id="@+id/empty_TV"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:textColor="#0c2c0c"
android:text="No Announcements Found"
android:textStyle="bold"
android:textSize="20sp" />
<ListView
android:id="@+id/events_list"
android:padding="10dip"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
</ListView>
</RelativeLayout>
Fragment class
public class EventsList extends ListFragment implements
android.widget.AdapterView.OnItemClickListener{
View rootView;
static SharedPreferences sPrefs;
private NetWorkConnection nc;
private BaseAlerts alert;
private ListView events_listview;
private TextView emptyTV;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.events_list, container, false);
initUI();
uiListener();
return rootView;
}
What's wrong with my code? Can anyone please help?
Cat magazine
06-10 19:22:08.248: E/AndroidRuntime(1009): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ie.minoritybussiness/com.ie.minoritybussiness.dashboard.SampleEvents}: java.lang.RuntimeException: Content has view with id attribute 'android.R.id.list' that is not a ListView class
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.app.ActivityThread.access$600(ActivityThread.java:130)
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.os.Handler.dispatchMessage(Handler.java:99)
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.os.Looper.loop(Looper.java:137)
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.app.ActivityThread.main(ActivityThread.java:4745)
06-10 19:22:08.248: E/AndroidRuntime(1009): at java.lang.reflect.Method.invokeNative(Native Method)
06-10 19:22:08.248: E/AndroidRuntime(1009): at java.lang.reflect.Method.invoke(Method.java:511)
06-10 19:22:08.248: E/AndroidRuntime(1009): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-10 19:22:08.248: E/AndroidRuntime(1009): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-10 19:22:08.248: E/AndroidRuntime(1009): at dalvik.system.NativeStart.main(Native Method)
06-10 19:22:08.248: E/AndroidRuntime(1009): Caused by: java.lang.RuntimeException: Content has view with id attribute 'android.R.id.list' that is not a ListView class
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.app.ListFragment.ensureList(ListFragment.java:402)
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.app.ListFragment.onViewCreated(ListFragment.java:203)
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:843)
06-10 19:22:08.248: E/AndroidRuntime(1009): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1035)
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Content has a view with id attribute 'android.R.id.list' which is not a ListView class
This looks like your problem. There are two reasons why I might think this is happening.
-
You are specifying android id for a non-list view. Check your XML files anywhere you use
@android:id/list
as an identifier for a view. Rename it to something else. -
You use
ListFragment
/ListActivity
and not by defining a view with@android:id/list
as an identifier. These classes require this ID. See this post for details .
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Placed:
FragmentManager fragmentManager = getSupportFragmentManager();
instead:
FragmentManager fm = getFragmentManager();
Edit: If you are not using the support library, this is probably not the reason for the exception. I will give you an example how to do it:
FragmentManager fragmentManager = getSupportFragmentManager();
Fragment fragment = (ListFragment) fragmentManager
.findFragmentByTag("List");
if (fragment != null) {
fragmentManager.beginTransaction()
.add(R.id.fragment, fragment, "List").addToBackStack("List")
.commit();
}
So, I am not using findFragmentById. I am using findFragmentTag and when I replace (or add) a fragment, I put a tag ("List"). ListFragment is the custom fragment you created.
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