FilipLuch FilipLuch - 13 days ago 10
Android Question

Listview setAdapter Null Pointer Exception

I have data inside a table. when I set adapter from it, the app crashes, but if I load the info from server then everything is ok. I get NullPointerException on setting the listview's adapter. even though, I do exactly same things as when table is empty.

// check if database is empty
cursor = sh.getReadableDatabase().rawQuery(
"SELECT * FROM " + PetopenTable.TABLE_NAME, null);
if (cursor.getCount() < 1) {
//cursor is empty
tableHasData = false;
} else {
tableHasData = true;
}

if (tableHasData) {
// we have data in database, show it, then get info
// from server and reload the UI
Log.d("Cursor", "PetOpenFragment; cursor is not empty");
prepareListFromCursor(cursor);
// initialize the list
lview3 = (ListView) getActivity().findViewById(R.id.listView1);
adapter = new ListViewCustomAdapter(getActivity(), itemList);
// here adapter is not null
if (adapter != null) {
Log.d("Adapter in Petopen", "is not null");
lview3.setAdapter(adapter); // line 94
} else {
Log.d("ADapter in petopen", "is null");
}

// do not show the loading message as we can fill it instantly from database
// now get data from server to update
new getPetopenUsers().execute((Void) null);
} else {
// show loading and load from server, database is empty
Log.d("Cursor", "PetOpenFragment; cursor is empty");
new getPetopenUsers().execute((Void) null);
mDialog.setMessage("Loading...");
mDialog.setCancelable(false);
mDialog.show();
}
...
// inside prepareListFromCursor I initialize the itemlist
itemList = new ArrayList<Object>();
...
//when i get data from server, i initialize same as when there is data in table
lview3 = (ListView) getActivity().findViewById(R.id.listView1);
adapter = new ListViewCustomAdapter(getActivity(), itemList);
lview3.setAdapter(adapter);


Logcat error:

ATAL EXCEPTION: main
java.lang.NullPointerException
at com.petcial.petopen.fragments.petOpenFragment.onCreateView(petOpenFragment.java:94)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440)
at android.os.Handler.handleCallback(Handler.java)
at android.os.Handler.dispatchMessage(Handler.java)
at android.os.Looper.loop(Looper.java)
at android.app.ActivityThread.main(ActivityThread.java)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:126)
at dalvik.system.NativeStart.main(Native Method)





Update

Here is how i fill the itemList, i call this method after i parse the info from table

private void AddObjectToList(String image, String name, String status,
String distance, String location, String[] petImage,
String[] petName) {
// TODO Auto-generated method stub
bean = new ItemBean();
bean.setProfileImage(image);
bean.setName(name);
bean.setStatus(status);
bean.setDistance(distance);
bean.setLocation(location);
bean.setPetImage(petImage);
bean.setPetName(petName);
itemList.add(bean);

}

Answer

Finally I tried putting the whole thing which loads data from database inside an AsyncTask, and it worked. In case someone faced same problem here is how you have to do it:

Create an AsyncTask, which is called from onCreate or onViewCreated(as in my case, I fragment) In the doInBackground method I did not have anything, instead in the onPostExecute method, i call all the methods that processes all the data from cursor and initializes the list and adapter.

If someone has a better solution on how to make this inside an AsyncTask, please answer to this post.