This might be a noob question but I'm quite new to all this SQLite-Database-Cursor-Adapter-ListView-Do-It-Properly-Stuff.
What I have:
In my MainActivity
I have a ListView
. I use an SQLite database
and populate the ListView
with a custom adapter extending SimpleCursorAdapter
. By clicking on an item in my ActionBar
I activate Contextual Action Mode
. Everything is working so far.
What I want:
By clicking on a certain icon in my ListView item
the according database row should be deleted and the ListView
should be refreshed.
My question:
How do I refresh my Cursor
and my ListView
properly? When I don't use cursor.requery()
in my OnClickListener
and use cursor = dbm.getIOIOSensorsCursor()
instead I get a CursorIndexOutOfBoundsException
a few rows below at the line
int state = cursor.getInt(cursor.getColumnIndex(IOIOSensorSchema.STATE));
My app crashes, but after reloading it the database has been deleted and the according ListView item
is gone.
I guess the crash must have something to do with _position
in get getView
method because _position
is final
. However, when I use cursor.requery()
everything works as it should.
But this method is deprecated and it's documentation says "Don't use this...". I'm a friend of coding properly (I'm still a beginner and want to learn to code the right way and not quick-and-dirty) and want to know how to do this right. I don't know if it's important but I'm testing my app only on my (really fast) Nexus 4. There seem to be no problems with refreshing the Cursor
fast enough, but I wonder if it will work on slower devices. In case it's important for you my database will contain about 10-20 rows with about 12 columns. I guess this is a really small database.
Here is the relevant code of my custom adapter:
public class IOIOSensorCursorAdapterCam extends SimpleCursorAdapter
{
static class ViewHolder
{
ImageView stateIV, removeIV;
TextView nameTV, pinNumberTV, feedIDTV, freqTV;
}
private Context ctx;
private Cursor cursor;
private IodDatabaseManager dbm;
public IOIOSensorCursorAdapterCam(Context _context, int _layout,
Cursor _cursor, String[] _from, int[] _to, int _flags)
{
super(_context, _layout, _cursor, _from, _to, _flags);
ctx = _context;
cursor = _cursor;
dbm = new IodDatabaseManager(_context);
}
@Override
public View getView(final int _position, View _convertView,
ViewGroup _parent)
{
ViewHolder holder = null;
LayoutInflater inflater = (LayoutInflater) ctx
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
// There is no view at this position, we create a new one. In this case
// by inflating an xml layout.
if (_convertView == null)
{
// Inflate a layout
_convertView = inflater.inflate(R.layout.listview_item_sensor_cam,
null);
holder = new ViewHolder();
holder.stateIV = (ImageView) _convertView
.findViewById(R.id.stateImageView);
holder.nameTV = (TextView) _convertView
.findViewById(R.id.sensorNameTextView);
holder.pinNumberTV = (TextView) _convertView
.findViewById(R.id.sensorPinNumberTextView);
holder.feedIDTV = (TextView) _convertView
.findViewById(R.id.sensorFeedIDTextView);
holder.freqTV = (TextView) _convertView
.findViewById(R.id.sensorFrequencyTextView);
holder.removeIV = (ImageView) _convertView
.findViewById(R.id.removeImageView);
_convertView.setTag(holder);
}
// We recycle a View that already exists.
else
{
holder = (ViewHolder) _convertView.getTag();
}
// Set an OnClickListener to the "Delete Icon"
holder.removeIV.setOnClickListener(new OnClickListener()
{
@SuppressWarnings("deprecation")
@Override
public void onClick(View _view)
{
cursor.moveToPosition(_position);
// Delete sensor from database here
int sensorID = cursor.getInt(cursor
.getColumnIndex(IOIOSensorSchema.SENSOR_ID));
dbm.deleteIOIOSensor(sensorID);
// This leads to a "CursorIndexOutOfBoundsException" and cannot
// be used to refresh the ListView
// cursor = dbm.getIOIOSensorsCursor();
// Refresh ListView
cursor.requery();
notifyDataSetChanged();
}
});
cursor.moveToPosition(_position);
if (cursor.getCount() > 0)
{
int state = cursor.getInt(cursor
.getColumnIndex(IOIOSensorSchema.STATE));
if (state == 0)
{
holder.stateIV.setImageResource(R.drawable.av_play_over_video);
holder.stateIV.setColorFilter(ctx.getResources().getColor(
R.color.hint_lighter_gray));
// _convertView.setAlpha((float) 0.5);
holder.nameTV.setTextColor(ctx.getResources().getColor(
R.color.hint_darker_gray));
}
else
{
holder.stateIV.setImageResource(R.drawable.av_pause_over_video);
holder.stateIV.setColorFilter(ctx.getResources().getColor(
android.R.color.holo_green_light));
// _convertView.setAlpha((float) 1);
holder.nameTV.setTextColor(ctx.getResources().getColor(
android.R.color.black));
}
// Set the sensor's name to the according TextView
String sensorName = cursor.getString(cursor
.getColumnIndex(IOIOSensorSchema.NAME));
holder.nameTV.setText(sensorName);
// Set the sensor's pin number to the according TextView
int pinNumber = cursor.getInt(cursor
.getColumnIndex(IOIOSensorSchema.PIN_NUMBER));
holder.pinNumberTV.setText("" + pinNumber);
// Set the sensor's feed ID to the according TextView
int feedID = cursor.getInt(cursor
.getColumnIndex(IOIOSensorSchema.FEED_ID));
holder.feedIDTV.setText("" + feedID);
// Set the sensor's frequency to the according TextView
int frequency = cursor.getInt(cursor
.getColumnIndex(IOIOSensorSchema.FREQUENCY));
int timeUnit = cursor.getInt(cursor
.getColumnIndex(IOIOSensorSchema.TIME_UNIT));
String frequencyTextViewText = "";
switch (timeUnit)
{
case IodIOIOSensor.TIME_UNIT_MINUTES:
frequencyTextViewText = frequency + " min";
break;
case IodIOIOSensor.TIME_UNIT_HOURS:
frequencyTextViewText = frequency + " h";
break;
default:
frequencyTextViewText = frequency + " sec";
break;
}
holder.freqTV.setText(frequencyTextViewText);
}
return _convertView;
}
}
Edit:
Here is my relevant code from the OnCickListener after implementing the solution:
// Set an OnClickListener to the "Delete Icon"
holder.removeIV.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View _view)
{
cursor.moveToPosition(_position);
// Delete sensor from database here
int sensorID = cursor.getInt(cursor
.getColumnIndex(IOIOSensorSchema.SENSOR_ID));
dbm.deleteIOIOSensor(sensorID);
Toast.makeText(ctx, R.string.toast_sensor_deleted,
Toast.LENGTH_SHORT).show();
// Refresh ListView
cursor = dbm.getIOIOSensorsCursor();
swapCursor(cursor);
notifyDataSetChanged();
}
});
How do I refresh my Cursor and my ListView properly?
You "refresh [your] Cursor" by running your code again to get the Cursor
, using the code you used to create the original Cursor
(on a background thread, please). You refresh your ListView
by calling changeCursor()
or swapCursor()
on the CursorAdapter
.