Refresh a ListView with a cursor with new data from DB

Question

I have a problem refreshing a ListView. I call my ListView Activity, I get the data from DB with a SQL statment with a cursor, I draw the ListView with a custom adapter (extends BaseAdapter), all works fine.

I want to put an EditText on the top to search items on my ListView, filter the actual view, same Activity, with the typed text. I getText() from EditText, and make a new SQL statment filtering the results with this text. I have checked that the cursor has the correct filtered results, but I use adapter.notifyDataSetChanged() trying to update the ListView but nothing happens (no errors or force closes).

Can anyone help me or tell me some tips to obtain this simple search function working with a database? I have found many similar questions with ArrayLists + getFilter() + SimpleCursorAdapter, but it doesn't works with my DB and custom adapter.

Activity ListaCaracteres:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(es.hsk.ap.R.layout.lista_caracteres);

    try{
        hanyuDBHelper = new HanyuSQLHelper(this);
        hanyuDB = hanyuDBHelper.getReadableDatabase();
        c = hanyuDB.rawQuery(" SELECT * FROM Caracteres ", null);
    }
    catch(SQLiteException ex)
    {
        Toast mensajeError=Toast.makeText(getApplicationContext(), "Error accediendo a los datos", Toast.LENGTH_SHORT);
        mensajeError.show();
        Log.e("LogLugares", "Error en getReadableDatabase()", ex);
    }


    adapter = new AdapterListaCaracteres(this,c);
    listaCaracteres = (ListView)findViewById(es.hsk.ap.R.id.listaCaracteres);
    listaCaracteres.setAdapter(adapter);

    buscador = (EditText)findViewById(R.id.buscador);
    buscador.addTextChangedListener(new TextWatcher()
    {
        @Override
        public void onTextChanged( CharSequence arg0, int arg1, int arg2, int arg3)
        {
        }

        @Override
        public void beforeTextChanged( CharSequence arg0, int arg1, int arg2, int arg3)
        {
            // TODO Auto-generated method stub

        }

        @Override
        public void afterTextChanged(Editable arg0)
        {
            // TODO Auto-generated method stub

            String texto="";
            texto=buscador.getText().toString();

            c = hanyuDB.rawQuery(" SELECT * FROM Caracteres WHERE significado LIKE '%"+texto+"%'", null);
            adapter.notifyDataSetChanged();
        }
    });
}

My custom adapter, AdapterListaCaracteres extends from BaseAdapter:

public class AdapterListaCaracteres extends BaseAdapter implements ListAdapter{

private Context  mContext;
private Cursor  datos;
private LayoutInflater inflater;

public AdapterListaCaracteres(Context  context, Cursor  c){
    this.mContext = context;
    this.datos = c;
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return datos.getCount();
}

@Override
public Object  getItem(int position) {
    // TODO Auto-generated method stub
    return datos.getString(position);
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return 0;
}

public View  getView(int position, View  convertView, ViewGroup parent) {
    // TODO Auto-generated method stub

    View item = convertView;
    ViewHolder holder;

    inflater = (LayoutInflater) mContext.getSystemService(Context .LAYOUT_INFLATER_SERVICE);
    datos.moveToPosition(position);

    if(item==null){
        try{
            item = inflater.inflate(es.hsk.ap.R.layout.caracter, null);
        }
        catch(InflateException ex)
        {

        }


        holder = new ViewHolder();
        holder.caracter = (TextView)item.findViewById(es.hsk.ap.R.id.caracter);
        holder.pinyin = (TextView)item.findViewById(es.hsk.ap.R.id.pinyin);
        holder.significado = (TextView)item.findViewById(es.hsk.ap.R.id.significado);

        item.setTag(holder);
    }
    else{
        holder = (ViewHolder)item.getTag();
    }           

    holder.caracter.setText(datos.getString(2));            
    holder.pinyin.setText(datos.getString(3));  
    holder.significado.setText(datos.getString(4));

    return item;

}
static class ViewHolder{
    TextView caracter;
    TextView pinyin;
    TextView significado;
}
}

I think this link will hwlp you... <stackoverflow.com/questions/6837397/…> Thanks... — user4232
– user4232, Commented Apr 2, 2012 at 10:07
try extend CursorAdapter class and use this constructor developer.android.com/reference/android/support/v4/widget/… — Jaiprakash Soni
– Jaiprakash Soni, Commented Apr 2, 2012 at 10:57
I have tried to change to CursorAdapter, ListView works ok, but it stills no refresh. I have tried requery() cursor, nothing happens, adapter.changeCursor(newCursor) throws exception "attempt to acquire a reference on a close SQLiteClosable", but I don't close any SQL objet... I'm surprised how difficult is to update a simply ListView :( Thanks — Pelanes
– Pelanes, Commented Apr 2, 2012 at 13:24
Also tried AsyncTask, but I don't see anything happens to call adapter.notifyDataSetChanged() there instead into the activity, the same. I have also run the program onto Android 2.1, 2.2, and 4.0, for a possible bug (there are a lot of questions about that, and no clear answer). — Pelanes
– Pelanes, Commented Apr 2, 2012 at 13:29

Code Maverick · Accepted Answer · 2012-04-06 14:58:22Z

1

Try this:

/*
 * Listener que actuará cuando se escriba en el EditText
 */
buscador.setOnKeyListener(new OnKeyListener() {

    @Override
    public boolean onKey(View v, int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        String texto = "";
        texto = buscador.getText().toString();
        c = hanyuDB.rawQuery(" SELECT * FROM Caracteres WHERE significado LIKE '%"                                                                                         + texto + "%'", null);

        AdapterListaCaracteres adapter2 = new AdapterListaCaracteres(getApplicationContext(), c, false);
        listaCaracteres.setAdapter(adapter2);
        return false;
    }

});
/*********************************************/

Good Luck ;)

ALEX

edited Apr 6, 2012 at 14:58

Code Maverick

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answered Apr 6, 2012 at 9:35

Alex Muni

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Comments

Pelanes · Accepted Answer · 2012-04-13 14:01:43Z

Now it's working! A friend of mine (Thanks Muni!) found a better way to filter a listview result dinamically with EditText:

buscador.setOnKeyListener(new OnKeyListener() {

        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {

instead of:

buscador.addTextChangedListener(new TextWatcher()
{

Thanks all people for your help.

EDIT:

Updating @AlexMuni and my own answer, onKey() method runs perfectly on emulator, but doesn't works fine in real devices.

I finally have done it perfectly with the previous method:

buscador = (EditText)findViewById(R.id.buscador); 
    buscador.addTextChangedListener(new TextWatcher()
    {
        @Override
        public void onTextChanged( CharSequence arg0, int arg1, int arg2, int arg3)
        {
            texto = buscador.getText().toString();
            c = hanyuDB.rawQuery(
                    " SELECT * FROM Caracteres WHERE significado LIKE '%"
                            + texto + "%'", null);
            AdapterListaCaracteres adapter2 = new AdapterListaCaracteres(ListaCaracteres.this, c, false);
            listaCaracteres.setAdapter(adapter2);
        }

        @Override
        public void beforeTextChanged( CharSequence arg0, int arg1, int arg2, int arg3)
        {
        }

        @Override
        public void afterTextChanged(Editable arg0)
        {
        }
    });

mayank_droid · Accepted Answer · 2013-08-02 08:15:26Z

0

Re-initialize the Adapter instead of notifydatasetchanged():

    adapter = new AdapterListaCaracteres(this,c);
    listaCaracteres.setAdapter(adapter);

edited Aug 2, 2013 at 8:15

user1448729

answered Apr 2, 2012 at 10:10

mayank_droid

1,01510 silver badges19 bronze badges

3 Comments

Pelanes Over a year ago

Thanks, but if I do that, I obtain a Force Close, LogCat: 04-02 10:19:53.984: E/AndroidRuntime(565): Uncaught handler: thread main exiting due to uncaught exception 04-02 10:19:54.004: E/AndroidRuntime(565): java.lang.NullPointerException 04-02 10:19:54.004: E/AndroidRuntime(565): at es.hsk.ap.caracteres.AdapterListaCaracteres.getView(AdapterListaCaracteres.java:56) 04-02 10:19:54.004: E/AndroidRuntime(565): at android.widget.AbsListView.obtainView(AbsListView.java:1274) 04-02 10:19:54.004: E/AndroidRuntime(565): at android.widget.ListView.measureHeightOfChildren(ListView.java:1147)

mayank_droid Over a year ago

then set adapter null once and then reinitialize it

Pelanes Over a year ago

I have tried to put null the adapter, but when I'm trying to setAdapter it throws the same NullPointerException. I have also tried to put ListView.setAdapter(null), and then setAdapter(adapter), but the same :(

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