Android contacts api

Question

        I used that example but it only display the name and number displayed are null
        I have no idea about it pls give me solution      


     package org.example.cp;

     import java.util.ArrayList;

   import android.app.Activity;
   import android.content.ContentResolver;
   import android.database.Cursor;
   import android.os.Bundle;
    import android.provider.Contacts.People;
   import android.util.Log;
  import android.widget.ArrayAdapter;
  import android.widget.ListView;

  public class ContentUserDemo extends Activity {
  private static final String TAG = "ContentUserDemo";
   private ArrayList<String> list;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    // Get content provider and cursor
    ContentResolver r = getContentResolver();
    Cursor cursor = r.query(People.CONTENT_URI, null, null, null, null);

    // Let activity manage the cursor
    startManagingCursor(cursor);
    Log.d(TAG, "cursor.getCount()=" + cursor.getCount());

    // Get value from content provider
    int nameIndex = cursor.getColumnIndexOrThrow(People.NAME);
    int numberIndex = cursor.getColumnIndexOrThrow(People.NUMBER);

    cursor.moveToFirst();
    list = new ArrayList<String>();
    do {
        String name = cursor.getString(nameIndex);
        String number = cursor.getString(numberIndex);
        list.add(number + ": " +name);
    } while (cursor.moveToNext());

    // Get the list view
    ListView listView = (ListView) findViewById(R.id.listView);
    ArrayAdapter<String> aa = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, list);
    listView.setAdapter(aa);
}

}