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android – Listview with CursorAdapter

Posted by: admin June 15, 2020 Leave a comment

Questions:

I’m developing an application which displays Phone contacts with CursorAdapter.
When I run it, I faced with a list view which repeated just one contact as bellow
(“david” is one of my contacts, just repeated in listview)

david
017224860

david
017224860

david
017224860

david
017224860

david
017224860

david
017224860
.

.

.

.

My activity looks like

public class Contacts extends Activity {    
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.contacts);

    Cursor cursor = getContentResolver()
        .query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
               null, null, null, null);

    startManagingCursor(cursor);

    ContactCursorAdapterCT adapter= new ContactCursorAdapterCT(Contacts.this, cursor);
     ListView contactLV = (ListView) findViewById(R.id.listviewblcontactsDB);

    contactLV.setAdapter(adapter);

And my cursorAdapter looks like:

public class ContactCursorAdapterCT extends CursorAdapter {
       public ContactCursorAdapterCT(Context context, Cursor c) {
    super(context, c);
    // TODO Auto-generated constructor stub
}

@Override
public void bindView(View view, Context context, Cursor cursor) {

    while (cursor.moveToNext()) {

        TextView name = (TextView)view.findViewById(R.id.blacklistDB1);               
          name.setText(cursor.getString(cursor.getColumnIndex
          (ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME)));

        TextView phone = (TextView)view.findViewById(R.id.blacklistDB2); 
          phone.setText(cursor.getString(cursor.getColumnIndex
          (ContactsContract.CommonDataKinds.Phone.NUMBER)));

    }
}

@Override
public View newView(Context context, Cursor cursor, ViewGroup parent)
{
    // TODO Auto-generated method stub

    LayoutInflater inflater = LayoutInflater.from(context);

    View v = inflater.inflate(R.layout.lv, parent, false);
            bindView(v, context, cursor);
           return v;
}
How to&Answers:

I noticed a few points:

  1. A CursorAdapter moves the Cursor for you, take out your call to cursor.moveToNext().
  2. The adapter’s getView() calls newView() and bindView() on it’s own; you shouldn’t call these methods yourself.
  3. You should watch the Android developer’s lectures at Google IO to learn tips and tricks about speeding up your adapter. Tips like:
    • Using a ViewHolder, rather than calling findViewById() repeatedly.
    • Saving the indices of your Cursor, rather than calling getColumnIndex() repeatedly.
    • Fetching the LayoutInflater once and keeping a local reference.

Answer:

Also, I suggest you switch from using CursorManager to using CursorLoader. This is documented in the Android API guide, under Loaders. A specific example that you might find useful is
here.

A Cursor Adapter “connects” a Cursor to a ListView. The Cursor is a data view of the data, and the ListView is a UI view of the same data. You don’t need to program anything to make the ListView stay in sync with the Cursor, that’s all handled automatically.

You do need to tell the ListView which columns in the Cursor it should display, See the documentation for the SimpleCursorAdapter class. I usually use that class unless I have to modify the data as I move it from the Cursor to the ListView.