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PORefresh expandable list using a content observer (Android)
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copied!<p>I have an expandable list, with a custom adapter, two cursor (from base expandable list adapter), and a content provider.</p> <p>Now, my main objective is to refresh this expandable list, after inserting new data with a activity that is called with a intent. I'm trying a Content Observer, but with no success, because no refresh is done.</p> <p>I put the relevant code (I think). Thank you very much.</p> <pre><code>public class ActPlacesManagement extends Activity{ private static final int DELETE_ID = Menu.FIRST; private static final String TAG = null; public Cursor mPlacesCursor; public Cursor mBoxesCursor; ExpandableListView lstCategorias; AdpPlacesManagement adapter; String message, message1, message2; String novo_local, nova_caixa; Button btnNewPlace, btnNewBox; Handler handler; private static final String[] PROJECTION_PLACES = new String[] { ProvPersonalArchive.KEY_ROWID_PLACES, ProvPersonalArchive.KEY_DESIG_PLACES, }; private static final String[] PROJECTION_BOXES = new String[] { ProvPersonalArchive.KEY_ROWID_BOXES, ProvPersonalArchive.KEY_DESIG_BOXES, ProvPersonalArchive.KEY_PLACE_BOXES, }; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.act_places_management); mPlacesCursor = getContentResolver().query(ProvPersonalArchive.CONTENT_URI_PLACES, PROJECTION_PLACES, null, null, null); mBoxesCursor = getContentResolver().query(ProvPersonalArchive.CONTENT_URI_BOXES, PROJECTION_BOXES, null, null, null); lstCategorias = (ExpandableListView)this.findViewById(R.id.expandableGestaoCategorias); adapter = new AdpPlacesManagement(this, mPlacesCursor, mBoxesCursor, this); lstCategorias.setAdapter(adapter); lstCategorias.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() { @Override public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) { return lstCategorias_onGroupClick(parent, v, groupPosition, id); } }); lstCategorias.setOnChildClickListener(new ExpandableListView.OnChildClickListener() { @Override public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) { return lstCategorias_onChildClick(parent, v, groupPosition, childPosition, id); } }); btnNewPlace = (Button)this.findViewById(R.act_gestao_categorias.novo_lugar); btnNewBox = (Button)this.findViewById(R.act_gestao_categorias.nova_caixa); btnNewPlace.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { btnNewPlace_onClick(v); } }); btnNewBox.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { btnNewBox_onClick(v); } }); registerForContextMenu(lstCategorias); mPlacesCursor.registerContentObserver(new ObsPersonalArchive(handler)); mBoxesCursor.registerContentObserver(new ObsPersonalArchive(handler)); } // Eventos da lista de locais e caixas public boolean lstCategorias_onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) { return false; } public boolean lstCategorias_onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) { return false; } // Termina a actividade e volta à ActInicial, levando o local public void finish() { // Prepare data intent Intent data = new Intent(); setResult(RESULT_OK, data); data.putExtra("local", message); // Activity finished ok, return the data super.finish(); } @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.act_start, menu); return true; } // Eventos dos botões para criar novo local e caixa public void btnNewPlace_onClick(View view) { Intent intent = new Intent(this, ActNewPlace.class); startActivityForResult(intent, 1); } public void btnNewBox_onClick(View view) { Intent intent = new Intent(this, ActNewBox.class); startActivityForResult(intent, 2); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (resultCode == RESULT_OK && requestCode == 1) { if (data.hasExtra("novo_local") && data.hasExtra("nova_caixa")) { // Chama o método para gravar o local na base de dados Toast.makeText(this, "New place created!", Toast.LENGTH_LONG).show(); } } if (resultCode == RESULT_OK && requestCode == 2) { if (data.hasExtra("novo_local") && data.hasExtra("nova_caixa")) { String novo_local = data.getExtras().getString("novo_local"); String nova_caixa = data.getExtras().getString("nova_caixa"); Toast.makeText(this, novo_local + nova_caixa, Toast.LENGTH_LONG).show(); } } } public class ObsPersonalArchive extends ContentObserver { public ObsPersonalArchive(Handler handler) { super(handler); } @Override public void onChange(boolean selfChange) { super.onChange(selfChange); } } </code></pre> <p>}</p> <p>Michael, the new class I wrote:</p> <pre><code>import android.app.Activity; import android.content.Intent; import android.database.ContentObserver; import android.database.Cursor; import android.database.DataSetObserver; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.util.Log; import android.view.ContextMenu; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ContextMenu.ContextMenuInfo; import android.widget.Button; import android.widget.ExpandableListAdapter; import android.widget.ExpandableListView; import android.widget.Toast; import android.support.v4.app.FragmentActivity; import android.support.v4.app.LoaderManager; import android.support.v4.content.CursorLoader; import android.support.v4.content.Loader; import android.support.v4.widget.CursorAdapter; public class ActPlacesManagement extends FragmentActivity implements LoaderManager.LoaderCallbacks<Cursor>{ private static final int DELETE_ID = Menu.FIRST; private static final String TAG = null; public Cursor mPlacesCursor; public Cursor mBoxesCursor; ExpandableListView lstCategorias; AdpPlacesManagement adapter; String message, message1, message2; String novo_local, nova_caixa; Button btnNewPlace, btnNewBox; Handler handler; LoaderManager loaderManager = getSupportLoaderManager(); private static final String[] PROJECTION_PLACES = new String[] { ProvPersonalArchive.KEY_ROWID_PLACES, // 0 ProvPersonalArchive.KEY_DESIG_PLACES, // 1 }; private static final String[] PROJECTION_BOXES = new String[] { ProvPersonalArchive.KEY_ROWID_BOXES, // 0 ProvPersonalArchive.KEY_DESIG_BOXES, // 1 ProvPersonalArchive.KEY_PLACE_BOXES, // 2 }; private static final int PLACES_LOADER = 1; private static final int BOXES_LOADER = 2; private LoaderManager.LoaderCallbacks<Cursor> mCallbacks; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.act_places_management); mPlacesCursor = getContentResolver().query(ProvPersonalArchive.CONTENT_URI_PLACES, PROJECTION_PLACES, null, null, null); mBoxesCursor = getContentResolver().query(ProvPersonalArchive.CONTENT_URI_BOXES, PROJECTION_BOXES, null, null, null); // Lista de locais e caixas lstCategorias = (ExpandableListView)this.findViewById(R.id.expandableGestaoCategorias); adapter = new AdpPlacesManagement(this, mPlacesCursor, mBoxesCursor, this); lstCategorias.setAdapter(adapter); lstCategorias.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() { @Override public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) { return lstCategorias_onGroupClick(parent, v, groupPosition, id); } }); lstCategorias.setOnChildClickListener(new ExpandableListView.OnChildClickListener() { @Override public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) { return lstCategorias_onChildClick(parent, v, groupPosition, childPosition, id); } }); // Botões para novo lugar e caixa btnNewPlace = (Button)this.findViewById(R.act_gestao_categorias.novo_lugar); btnNewBox = (Button)this.findViewById(R.act_gestao_categorias.nova_caixa); btnNewPlace.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { btnNewPlace_onClick(v); } }); btnNewBox.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { btnNewBox_onClick(v); } }); registerForContextMenu(lstCategorias); getSupportLoaderManager().initLoader(BOXES_LOADER, null, mCallbacks); getSupportLoaderManager().initLoader(PLACES_LOADER, null, mCallbacks); } // Eventos da lista de locais e caixas public boolean lstCategorias_onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) { return false; } public boolean lstCategorias_onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) { return false; } public void finish() { Intent data = new Intent(); setResult(RESULT_OK, data); data.putExtra("local", message); super.finish(); } @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.act_start, menu); return true; } // Eventos dos botões para criar novo local e caixa public void btnNewPlace_onClick(View view) { Intent intent = new Intent(this, ActNewPlace.class); startActivityForResult(intent, 1); } public void btnNewBox_onClick(View view) { Intent intent = new Intent(this, ActNewBox.class); startActivityForResult(intent, 2); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (resultCode == RESULT_OK && requestCode == 1) { if (data.hasExtra("novo_local") && data.hasExtra("nova_caixa")) { Toast.makeText(this, "New place created!", Toast.LENGTH_LONG).show(); } } if (resultCode == RESULT_OK && requestCode == 2) { if (data.hasExtra("novo_local") && data.hasExtra("nova_caixa")) { String novo_local = data.getExtras().getString("novo_local"); String nova_caixa = data.getExtras().getString("nova_caixa"); Toast.makeText(this, novo_local + nova_caixa, Toast.LENGTH_LONG).show(); } } } // Menu de contexto public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { super.onCreateContextMenu(menu, v, menuInfo); ExpandableListView.ExpandableListContextMenuInfo info; try { // Casts the incoming data object into the type for AdapterView objects. info = (ExpandableListView.ExpandableListContextMenuInfo) menuInfo; } catch (ClassCastException e) { // If the menu object can't be cast, logs an error. Log.e(TAG, "bad menuInfo", e); return; } int place = ExpandableListView.getPackedPositionGroup(info.packedPosition); int box = ExpandableListView.getPackedPositionChild(info.packedPosition); int tipo_clic = ExpandableListView.getPackedPositionType(info.packedPosition); String titulo = null; if (tipo_clic == ExpandableListView.PACKED_POSITION_TYPE_CHILD){ titulo = (String) adapter.getChild(place, box); menu.add(0, DELETE_ID, 0, R.string.delete_box); } if (tipo_clic == ExpandableListView.PACKED_POSITION_TYPE_GROUP){ titulo = (String) adapter.getGroup(place); menu.add(0, DELETE_ID, 0, R.string.delete_place); } if (titulo == null) { // For some reason the requested item isn't available, do nothing return; } menu.setHeaderTitle(titulo); } public boolean onContextItemSelected(MenuItem item) { ExpandableListView.ExpandableListContextMenuInfo info = (ExpandableListView.ExpandableListContextMenuInfo) item.getMenuInfo(); int tipo_clic = ExpandableListView.getPackedPositionType(info.packedPosition); switch(item.getItemId()) { case DELETE_ID: if (tipo_clic == ExpandableListView.PACKED_POSITION_TYPE_CHILD){ Toast.makeText(this, "The box was deleted", Toast.LENGTH_LONG).show(); } if (tipo_clic == ExpandableListView.PACKED_POSITION_TYPE_GROUP){ Toast.makeText(this, "The place was deleted", Toast.LENGTH_LONG).show(); } return true; } return super.onContextItemSelected(item); } public Loader<Cursor> onCreateLoader(int id, Bundle arg1) { CursorLoader cursorLoader = new CursorLoader(getBaseContext()); if (id == BOXES_LOADER){ cursorLoader = new CursorLoader(ActPlacesManagement.this, ProvPersonalArchive.CONTENT_URI_BOXES, PROJECTION_BOXES, null, null, null); }; if (id == PLACES_LOADER){ cursorLoader = new CursorLoader(ActPlacesManagement.this, ProvPersonalArchive.CONTENT_URI_PLACES, PROJECTION_PLACES, null, null, null); }; return cursorLoader; } public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) { switch (loader.getId()) { case BOXES_LOADER: mPlacesCursor = cursor; break; case PLACES_LOADER: mBoxesCursor = cursor; break; } adapter = new AdpPlacesManagement(this, mPlacesCursor, mBoxesCursor, this); lstCategorias.setAdapter(adapter); } public void onLoaderReset(Loader<Cursor> loader) { switch (loader.getId()) { case BOXES_LOADER: mPlacesCursor = null; break; case PLACES_LOADER: mBoxesCursor = null; break; } adapter = new AdpPlacesManagement(this, mPlacesCursor, mBoxesCursor, this); } public class ObsPersonalArchive extends ContentObserver { public ObsPersonalArchive(Handler handler) { super(handler); } @Override public void onChange(boolean selfChange) { super.onChange(selfChange); } } } </code></pre> <p>And the errors</p> <blockquote> <p>12-17 17:28:59.775: I/ActivityThread(16376): enter process activity msg = 101 12-17 17:28:59.795: I/ActivityThread(16376): exit process activity msg = 101 12-17 17:28:59.805: I/ActivityThread(16376): enter process activity msg = 100 12-17 17:28:59.905: W/dalvikvm(16376): threadid=1: thread exiting with uncaught exception (group=0x2aacc8a0) 12-17 17:28:59.915: E/AndroidRuntime(16376): FATAL EXCEPTION: main 12-17 17:28:59.915: E/AndroidRuntime(16376): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.smartmobilelife.personal.archive/com.smartmobilelife.personal.archive.ActPlacesManagement}: java.lang.NullPointerException 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2705) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2721) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.app.ActivityThread.access$2300(ActivityThread.java:132) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2071) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.os.Handler.dispatchMessage(Handler.java:99) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.os.Looper.loop(Looper.java:123) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.app.ActivityThread.main(ActivityThread.java:4669) 12-17 17:28:59.915: E/AndroidRuntime(16376): at java.lang.reflect.Method.invokeNative(Native Method) 12-17 17:28:59.915: E/AndroidRuntime(16376): at java.lang.reflect.Method.invoke(Method.java:521) 12-17 17:28:59.915: E/AndroidRuntime(16376): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:876) 12-17 17:28:59.915: E/AndroidRuntime(16376): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634) 12-17 17:28:59.915: E/AndroidRuntime(16376): at dalvik.system.NativeStart.main(Native Method) 12-17 17:28:59.915: E/AndroidRuntime(16376): Caused by: java.lang.NullPointerException 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.support.v4.app.LoaderManagerImpl.createLoader(LoaderManager.java:487) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.support.v4.app.LoaderManagerImpl.createAndInstallLoader(LoaderManager.java:496) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.support.v4.app.LoaderManagerImpl.initLoader(LoaderManager.java:550) 12-17 17:28:59.915: E/AndroidRuntime(16376): at com.smartmobilelife.personal.archive.ActPlacesManagement.onCreate(ActPlacesManagement.java:131) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 12-17 17:28:59.915: E/AndroidRuntime(16376): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2669) 12-17 17:28:59.915: E/AndroidRuntime(16376): ... 11 more</p> </blockquote>

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