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PONullPointerException in notifyDataSetChanged()
 

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  1. PONullPointerException in notifyDataSetChanged()
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    <p>I am trying for last 19 hours to update the <code>listFragment</code> but can't able to get working with <code>notifyDataSetChanged()</code>. I have visited a lot of thread on it but failed to make working it. I have a parent Fragment and inside this I have three <code>ListFragment</code>. The <code>ListFragment</code>s need to pass data among them and I am able to do this via <code>interface</code>. Information are being passed successfully. But the <code>ListView</code> is not updating. This is my trying code:</p> <pre><code>public class SubChaptersListFragment extends SherlockListFragment { ArrayAdapter&lt;String&gt; mAdapter = null; ArrayList&lt;String&gt; items = new ArrayList&lt;String&gt;(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); int layout = Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.HONEYCOMB ? android.R.layout.simple_list_item_activated_1 : android.R.layout.simple_list_item_1; Chapter instance = CompetitiveProgramming.chapterList.get(0); for (int i = 0; i &lt; instance.subchapterList.size(); i++) { items.add(instance.subchapterList.get(i).subChapterTitle); } mAdapter = new ArrayAdapter&lt;String&gt;(getSherlockActivity(), layout, items); setListAdapter(mAdapter); } @Override public void onStart() { super.onStart(); if (getFragmentManager().findFragmentById( R.id.sub_sub_category_fragment) != null) { getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE); } } // this function is invoked from another `fragment` and position is retrieved successfully public void updateList(int position) { Chapter instance = CompetitiveProgramming.chapterList.get(position); items.clear(); for (int i = 0; i &lt; instance.subchapterList.size(); i++) { items.add(instance.subchapterList.get(i).subChapterTitle); } mAdapter.notifyDataSetChanged(); // nullpointerException in this line } } </code></pre> <p><strong>Edit</strong> Logcat</p> <pre><code>08-13 18:33:30.670: E/AndroidRuntime(537): java.lang.NullPointerException 08-13 18:33:30.670: E/AndroidRuntime(537): at me.kaidul.uhunt.SubChaptersListFragment.updateList(SubChaptersListFragment.java:57) 08-13 18:33:30.670: E/AndroidRuntime(537): at me.kaidul.uhunt.CompetitiveProgramming.onChapterSelected(CompetitiveProgramming.java:214) 08-13 18:33:30.670: E/AndroidRuntime(537): at me.kaidul.uhunt.ChaptersListFragment.onListItemClick(ChaptersListFragment.java:60) 08-13 18:33:30.670: E/AndroidRuntime(537): at android.support.v4.app.ListFragment$2.onItemClick(ListFragment.java:58) 08-13 18:33:30.670: E/AndroidRuntime(537): at android.widget.AdapterView.performItemClick(AdapterView.java:284) 08-13 18:33:30.670: E/AndroidRuntime(537): at android.widget.ListView.performItemClick(ListView.java:3382) 08-13 18:33:30.670: E/AndroidRuntime(537): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1696) 08-13 18:33:30.670: E/AndroidRuntime(537): at android.os.Handler.handleCallback(Handler.java:587) </code></pre> <p>This is how I called the fragment from parentFragment:</p> <pre><code>@Override public void onChapterSelected(int position) { SubChaptersListFragment subChapterFrag = new SubChaptersListFragment(); if ( subChapterFrag != null) { subChapterFrag.updateList(position); } else { } } </code></pre>
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    1. PTQuestion
    1. USKaidul Islam
    1. USKaidul Islam
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      1. PONullPointerException in notifyDataSetChanged()
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      1. VTDownMod
    2. VO
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    1. COshow the logcat
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      1. PONullPointerException in notifyDataSetChanged()
      1. USMarcin Orlowski
    2. COI updated my question. Take a look
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      1. PONullPointerException in notifyDataSetChanged()
      1. USKaidul Islam
    3. COI think your `mAdapter` equals null in this case. Plz check for null before calling notifyDataSetChanged() on it.
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      1. PONullPointerException in notifyDataSetChanged()
      1. USRitesh Gune
 

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