问题
I'm having troubles with my Custom CursorAdapter and my ListView, the fact is, I can save data in my sqlite Database in my custom ContentProvider but my ListView is not populated.
I know DB Operations are heavy long operations, therefore I do it in another thread and furthermore CursorLoader is a subclass of AsyncTaskLoader, so it should be prepared for that.
With SimpleCursorAdapter works fine but with this Custom CursorAdapter not.
Can anyone tell me what is wrong and how could I solve it?
Thanks in advance.
My code is the following
public class TextNoteAdapter extends CursorAdapter {
/*********** Declare Used Variables *********/
private Cursor mCursor;
private Context mContext;
private static LayoutInflater mInflater=null;
/************* TextNoteAdapter Constructor *****************/
public TextNoteAdapter (Context context, Cursor cursor, int flags) {
super(context, cursor,flags);
mInflater =(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mContext = context;
mCursor = cursor;
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
//LayoutInflater inflater = LayoutInflater.from(parent.getContext());
View view = mInflater.inflate(R.layout.textnote_info, parent, false);
ViewHolder holder = new ViewHolder();
holder.note_name = (TextView)view.findViewById(R.id.note_name);
holder.creation_date = (TextView)view.findViewById(R.id.creation_date);
holder.modification_date = (TextView)view.findViewById(R.id.modification_date);
holder.label_creation_date = (TextView)view.findViewById(R.id.label_creation_date);
holder.label_modification_date = (TextView)view.findViewById(R.id.label_modification_date);
view.setTag(holder);
return view;
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
// here we are setting our data what means, take the data from the cursor and put it in views
View vi = view;
ViewHolder holder = (ViewHolder)view.getTag();
if(view==null){
/****** Inflate textnote_info.xml file for each row ( Defined below ) *******/
vi = mInflater.inflate(R.layout.textnote_info, null);
/************ Set holder with LayoutInflater ************/
vi.setTag( holder );
} else
holder=(ViewHolder)vi.getTag();
/************ Set Model values in Holder elements ***********/
holder.note_name.setText(cursor.getString(cursor.getColumnIndex(TextNotesDb.KEY_NOTE_NAME)));
holder.creation_date.setText(cursor.getString(cursor.getColumnIndex(TextNotesDb.KEY_CREATION_DATE)));
holder.modification_date.setText(cursor.getString(cursor.getColumnIndex(TextNotesDb.KEY_MODIFICATION_DATE)));
holder.label_creation_date.setText(Constants.LABEL_CREATION_DATE);
holder.label_modification_date.setText(Constants.LABEL_MODIFICATION_DATE);
}
@Override
protected void onContentChanged() {
// TODO Auto-generated method stub
super.onContentChanged();
notifyDataSetChanged();
}
/********* Create a holder Class to contain inflated xml file elements *********/
public static class ViewHolder{
public TextView note_name;
public TextView creation_date;
public TextView modification_date;
public TextView label_creation_date;
public TextView label_modification_date;
}
}
And here my MainActivity
import android.app.Activity;
import android.app.LoaderManager;
import android.content.CursorLoader;
import android.content.Intent;
import android.content.Loader;
import android.database.Cursor;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.CursorAdapter;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends Activity implements LoaderManager.LoaderCallbacks<Cursor>{
private Cursor cursor;
private Button addButton;
private ListView listView;
private TextNoteAdapter dataAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
displayListView();
addButton = (Button)findViewById(R.id.add_textnote);
addButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// starts a new Intent to add a Note
Intent intent = new Intent(getBaseContext(), TextNoteEdit.class);
Bundle bundle = new Bundle();
bundle.putString("mode", "add");
intent.putExtras(bundle);
startActivity(intent);
}
});
}
@Override
protected void onResume() {
super.onResume();
Log.i("TAG", "MainActivity:: onResume");
/** Starts a new or restarts an existing Loader in this manager **/
getLoaderManager().restartLoader(0, null, this);
}
private void displayListView() {
// That ensures a loader is initialized and active.
// If the loader specified by the ID already exists, the last created loader is reused.
// else initLoader() triggers the LoaderManager.LoaderCallbacks method onCreateLoader().
// This is where you implement the code to instantiate and return a new loader
getLoaderManager().initLoader(0, null, this);
// We get ListView from Layout and initialize
listView = (ListView) findViewById(R.id.textnote_list);
// DB takes long, therefore this operation should take place in a new thread!
new Handler().post(new Runnable() {
@Override
public void run() {
dataAdapter = new TextNoteAdapter(MainActivity.this, null, CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
listView.setAdapter(dataAdapter);
Log.i("TAG", "MainActivity:: Handler... Run()");
}
});
listView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> listView, View view, int position, long id) {
/** Get the cursor, positioned to the corresponding row in the result set **/
Cursor cursor = (Cursor) listView.getItemAtPosition(position);
// display the selected note
String noteName = cursor.getString(cursor.getColumnIndexOrThrow(TextNotesDb.KEY_NOTE_NAME));
Toast.makeText(getApplicationContext(), noteName, Toast.LENGTH_SHORT).show();
String rowId = cursor.getString(cursor.getColumnIndexOrThrow(TextNotesDb.KEY_ROWID));
// starts a new Intent to update/delete a Textnote
// pass in row Id to create the Content URI for a single row
Intent intent = new Intent(getBaseContext(), TextNoteEdit.class);
Bundle bundle = new Bundle();
bundle.putString("mode", "update");
bundle.putString("rowId", rowId);
intent.putExtras(bundle);
startActivityForResult(intent, 1);
}
});
}
/** This is called when a new Loader needs to be created.**/
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
Log.i("TAG", "MainActivity:: onCreateLoader");
String[] projection = {
TextNotesDb.KEY_ROWID,
TextNotesDb.KEY_GUID,
TextNotesDb.KEY_NOTE_NAME,
TextNotesDb.KEY_NOTE,
TextNotesDb.KEY_CREATION_DATE,
TextNotesDb.KEY_MODIFICATION_DATE
};
CursorLoader cursorLoader = new CursorLoader(this, MyContentProvider.CONTENT_URI, projection, null, null, null);
return cursorLoader;
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
// Swap the new cursor in. (The framework will take care of closing the
// old cursor once we return.)
dataAdapter.swapCursor(data);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
// This is called when the last Cursor provided to onLoadFinished()
// above is about to be closed. We need to make sure we are no
// longer using it.
dataAdapter.swapCursor(null);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
回答1:
As in comment below my Question, I could solve it by adding 2 lines. Now it should look like this
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
// Swap the new cursor in. (The framework will take care of closing the
// old cursor once we return.)
dataAdapter.notifyDataSetChanged(); // <-
listView.setAdapter(dataAdapter); // <-
dataAdapter.swapCursor(data);
}
来源：https://stackoverflow.com/questions/24447055/my-custom-cursoradapter-doesnt-update-my-listview