Hi,
I am having a real problem here with discovering bluetooth devices. I
am making a method that returns a List with all devices that were
discovered. This method triggers other methods that executes the
discovery and establish the BroadcastReceivers.
THE PROBLEM is that the method returns before the BroadcastReceivers
finds the devices. This results in returning an empty list every time
by the getDiscoveredList() because the List hasn't been filled yet by
the Receivers. List made global where all methods and Receivers share
the same List. The List is filled with devices after the method
returns.
Here is my code:
ArrayList<Device> discoveredDevices = new ArrayList<Device>();
public ArrayList<Device> getDiscoveredList() {
isDiscovering = true;
monitorDiscovery();
discoverDevices();
Log.d("Save", "Before - btAdapter.isDiscovering()
"+btAdapter.isDiscovering());
while (btAdapter.isDiscovering()) {
// Waiting for discovery to end. Assuming
that during discovery devices have already been added
// in discoveredDevices because they are
added when BluetoothDevice.ACTION_FOUND
// When discovery ends, no nearby devices is
expected to be found by the
// discoveryResult BroadcastReceiver because
I am not discovering outside this loop
}
Log.d("Save", "After - btAdapter.isDiscovering()
"+btAdapter.isDiscovering());
Log.d("Save", "Returning from getDiscoveredList()");
return discoveredDevices;
}
private void monitorDiscovery() {
registerReceiver(discoveryMonitor, new IntentFilter(
BluetoothAdapter.ACTION_DISCOVERY_STARTED));
registerReceiver(discoveryMonitor, new IntentFilter(
BluetoothAdapter.ACTION_DISCOVERY_FINISHED));
}
private void discoverDevices() {
while (!btAdapter.isEnabled()) { // If Bluetooth is still
opening, then wait till opened
}
discoveredDevices.clear(); //Clear the List
btAdapter.startDiscovery();
while (!btAdapter.isDiscovering()) { //Wait till discovery
starts
}
BroadcastReceiver discoveryResult = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
BluetoothDevice remoteDevice;
remoteDevice = intent
.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
short rssi =
intent.getShortExtra(BluetoothDevice.EXTRA_RSSI,
Short.MIN_VALUE);
Toast.makeText(
getApplicationContext(),
"Discovered: " +
remoteDevice.getName() + " RSSI: "
+ rssi,
Toast.LENGTH_SHORT).show();
if (!discoveredDevices.contains(remoteDevice)) {
discoveredDevices.add(new
Device(remoteDevice, rssi));
Log.d("Save", "Name: " +
remoteDevice.getName());
Log.d("Save", "Address: " +
remoteDevice.getAddress());
Log.d("Save", "RSSI: " + rssi);
Log.d("Save", "Size Now: " +
discoveredDevices.size());
}
}
};
registerReceiver(discoveryResult, new
IntentFilter(BluetoothDevice.ACTION_FOUND));
return;
}
BroadcastReceiver discoveryMonitor = new BroadcastReceiver() {
String dStarted = BluetoothAdapter.ACTION_DISCOVERY_STARTED;
String dFinished = BluetoothAdapter.ACTION_DISCOVERY_FINISHED;
@Override
public void onReceive(Context context, Intent intent) {
if (dStarted.equals(intent.getAction())) {
// Discovery has started.
Log.d("Save", "Discovery Started...");
} else if (dFinished.equals(intent.getAction())) {
Log.d("Save", "Discovery Finished...");
Log.d("Save", "doneDiscovering()
isDiscovering = false");
isDiscovering = false;
Log.d("Save","Discovery Completed...
discoveredDevices Size = "
+ discoveredDevices.size());
for (int i = 0; i < discoveredDevices.size();
i++) {
Log.d("Save", "Device(" + i + "): "
+
discoveredDevices.get(i).getDevice().getName()
+ " RSSI= " +
discoveredDevices.get(i).getRssi());
}
Log.d("Save", "Size at doneDiscovering() :
"+discoveredDevices.size());
}
}
};
Monitoring the LogCat, the getDiscoveredList() method is executed and
returns before the BroadcastReceiver discoveryMonitor or the
BroadcastReceiver discoveryResult does anything although they are
triggered within this method, and it is ensured by the LogCat that the
discovery starts and ends before returning.
I JUST CAN'T UNDERSTAND how can discovery starts and ends before
saving the discovered devices or event logging "Discovery Started..."
and "Discovery Completed..." which is logged when the intentAction is
startedDiscovery or endedDiscovery.
It looks as the program is insisting to complete the method
getDiscoveredList() before monitoring the bluetooth discovery because
I tried to pause the method until the devices are saved or so, but
this didn't do nothing. The method was paused, then after that it
returned then the discovery work happened!
PLEASE I need help because I am so desperate with this problem. I have
tried every single turn-around I am aware of, but nothing happened. It
seems because I don't know something about the order these methods or
Receivers work in.
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