In a simple app project at GitHub I have only 2 custom Java-files:
Adapter
and ViewHolder
for displaying Bluetooth devices in a RecyclerView
The MainActivity.java contains a method to be called, when user taps on a Bluetooth device in the RecyclerView
:
public void confirmConnection(String address) {
final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Do you want to pair to " + device + "?");
builder.setPositiveButton(R.string.button_ok,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
device.createBond();
}
});
builder.setNegativeButton(R.string.button_cancel, null);
builder.show();
}
And in the ViewHolder
class (in the DeviceListAdapter.java) the click listener is defined:
public class DeviceListAdapter extends
RecyclerView.Adapter<DeviceListAdapter.ViewHolder> {
private ArrayList<BluetoothDevice> mDevices = new ArrayList<BluetoothDevice>();
protected static class ViewHolder
extends RecyclerView.ViewHolder
implements View.OnClickListener {
private TextView deviceAddress;
public ViewHolder(View v) {
super(v);
v.setOnClickListener(this);
}
@Override
public void onClick(View v) {
String address = deviceAddress.getText().toString();
Toast.makeText(v.getContext(),
"How to call MainActivity.confirmConnection(address)?",
Toast.LENGTH_SHORT).show();
}
}
My problem:
How to call confirmConnection(address)
method from ViewHolder
s onClick
method?
I keep moving ViewHolder
class declaration between the 2 Java files and also tried putting it into its own file - and just can't find the right way.
Should I maybe add a field to ViewHolder
class and (when?) store a reference to MainActivity
instance there?
UPDATE:
This works for me, but seems to be a workaround (and also I was thinking of using LocalBroadcastReceiver
- which would be an even more hackish workaround) -
@Override
public void onClick(View v) {
String address = deviceAddress.getText().toString();
try {
((MainActivity) v.getContext()).confirmConnection(address);
} catch (Exception e) {
// ignore
}
}
To keep your classes decoupled, I'd suggest defining an interface on your adapter, something like:
public interface OnBluetoothDeviceClickedListener {
void onBluetoothDeviceClicked(String deviceAddress);
}
Then add a setter for this in your adapter:
private OnBluetoothDeviceClickedListener mBluetoothClickListener;
public void setOnBluetoothDeviceClickedListener(OnBluetoothDeviceClickedListener l) {
mBluetoothClickListener = l;
}
Then internally, in your ViewHolder
's onClick()
:
if (mBluetoothClickListener != null) {
final String addresss = deviceAddress.getText().toString();
mBluetoothClickListener.onBluetoothDeviceClicked(address);
}
Then just have your MainActivity
pass in a listener to the Adapter
:
mDeviceListAdapter.setOnBluetoothDeviceClickedListener(new OnBluetoothDeviceClickedListener() {
@Override
public void onBluetoothDeviceClicked(String deviceAddress) {
confirmConnection(deviceAddress);
}
});
This way you can reuse the adapter later without it being tied to that particular behavior.