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Android's bluetooth BluetoothDevice.ACTION_FOUND is not being triggered?

Posted by: admin June 15, 2020 Leave a comment

Questions:

I’m trying to manage several Bluetooth events from my app so the user will not need to leave the app & try to search/pair Bluetooth devices from Android settings.

I’m able to enumerate previously paired devices, and start discovery, however I cant find nearby devices.

Background info:

Device = Samsung Galaxy S6

OS = Android 6.0.1 , Kernel 3.4.0-750027

Bluetooth devices are visible via Android’s own built in discovery

Here is my relevant code:

package experiment.xyz.abc;
import android.app.ListActivity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Parcelable;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.lang.reflect.Method;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
/**
*      
* This activity is responsible for bluetooth device discovery, pairing, and selection.
* 1) user can search for nearby devices
* 2) pair with device
* 3) unpair a device
* 4) select a bt device( upon successful selection the activity navigates away).
*/
public class BluetDeviceListActivity extends ListActivity
{
public static String BLUETOOTH_DEVICE_ADDRESS= "BLUETOOTH_DEVICE_ADDRESS";
List<BluetoothDevice> bluetList;
BluetoothDeviceListAdapter newBluetoothDeviceListAdapter = null;
private  Set<BluetoothDevice> pairedDevices;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.bluet_list_view);
//instantiate adapter
newBluetoothDeviceListAdapter = new BluetoothDeviceListAdapter(this);
//populate bluet list
populatePairedBluetoothDevices();
//set the ListActivity's adapter with our custom adapter
setListAdapter(newBluetoothDeviceListAdapter);
//on item click get the associated item based index & use Intent to send BluetoothDevice
getListView().setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
BluetoothDevice bluetoothDevice= newBluetoothDeviceListAdapter.getListOfBluetoothDevices().get(position);
if (bluetoothDevice!=null) {
Intent returnIntent = new Intent();
returnIntent.putExtra(BLUETOOTH_DEVICE_ADDRESS, bluetoothDevice.getAddress());
setResult(RESULT_OK, returnIntent);
}
finish();
if (mReceiver!=null)
{
try {
unregisterReceiver(mReceiver);
}
catch (IllegalArgumentException exc)
{
exc.printStackTrace();
}
}
}
});
//cancel activity dialog
Button cancelButton = (Button) findViewById(R.id.cancelBluetoothDialogButton);
cancelButton.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View v) {
finish();
if (mReceiver!=null)
{
try {
unregisterReceiver(mReceiver);
}
catch (IllegalArgumentException exc)
{
exc.printStackTrace();
}
}
}
});
//search for bluetooth devices
Button searchAndPairButton = (Button) findViewById(R.id.searchPairButton);
searchAndPairButton.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View v) {
//update textview
populateDiscoveredBluetoothDevices();
}
});
//pair or unpair selected device
Button pairOrUnpairButton = (Button) findViewById(R.id.pairUnpairDialogButton);
pairOrUnpairButton.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View v) {
//TODO:
}
});
}//end onCreate
//discover nearby devices & add to list
private void populateDiscoveredBluetoothDevices()
{
StreamApiUtility.getBluetoothAdapter();
//is bluet enabled
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
//if already discovering cancel
if(mBluetoothAdapter.isDiscovering()){
mBluetoothAdapter.cancelDiscovery();
}
//start a new discovery
mBluetoothAdapter.startDiscovery();
}//end there are paired devices
else
{
Log.i("EEGdataCapture", "No paired devices, select Search & Pair.");
TextView textView  =(TextView) findViewById(R.id.textViewBluetoothListInstruction);
textView.setText("No paired devices, select Search & Pair.");
}
}
//query already paired & add to list
private void populatePairedBluetoothDevices()
{
StreamApiUtility.getBluetoothAdapter();
//is bluet enabled
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
//if already discovering cancel
if(mBluetoothAdapter.isDiscovering()){
mBluetoothAdapter.cancelDiscovery();
}
//start a new discovery
mBluetoothAdapter.startDiscovery();
//iterate paired/bonded devices and if there are any add them to the custom adapter
pairedDevices = mBluetoothAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
BluetoothDevice bluetoothDevice;
Iterator<BluetoothDevice> it = pairedDevices.iterator();
while (it.hasNext()) {
bluetoothDevice = (BluetoothDevice) it.next();
//add to adapter
newBluetoothDeviceListAdapter.addDevice(bluetoothDevice);
newBluetoothDeviceListAdapter.notifyDataSetChanged();
Log.i("EEGdataCapture", "paired device, name: " + bluetoothDevice.getName() + ", address: " + bluetoothDevice.getAddress());
}
}//end there are paired devices
else
{
Log.i("EEGdataCapture", "No paired devices, select Search & Pair.");
TextView textView  =(TextView) findViewById(R.id.textViewBluetoothListInstruction);
textView.setText("No paired devices, select Search & Pair.");
}
}
}
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
BluetoothDevice device;
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
Log.i("EEGdataCapture", "BluetoothDevice.ACTION_FOUND");
Log.i("EEGdataCapture", device.getName() + "\n" + device.getAddress());
//update list
newBluetoothDeviceListAdapter.addDevice(device);
newBluetoothDeviceListAdapter.notifyDataSetChanged();
}
else if (BluetoothDevice.ACTION_BOND_STATE_CHANGED.equals(action)) {
Log.i("EEGdataCapture", "BluetoothDevice.ACTION_BOND_STATE_CHANGED");
final int state = intent.getIntExtra(BluetoothDevice.EXTRA_BOND_STATE, BluetoothDevice.ERROR);
final int prevState = intent.getIntExtra(BluetoothDevice.EXTRA_PREVIOUS_BOND_STATE, BluetoothDevice.ERROR);
if (state == BluetoothDevice.BOND_BONDED && prevState == BluetoothDevice.BOND_BONDING) {
Toast.makeText(MyApp.getAppContext(), "Paired", Toast.LENGTH_SHORT).show();
} else if (state == BluetoothDevice.BOND_NONE && prevState == BluetoothDevice.BOND_BONDED) {
Toast.makeText(MyApp.getAppContext(), "Unpaired", Toast.LENGTH_SHORT).show();
}
}
else if (BluetoothDevice.ACTION_UUID.equals(action)) {
Log.i("EEGdataCapture", "BluetoothDevice.ACTION_UUID");
}
else if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
Log.i("EEGdataCapture", "BluetoothAdapter.ACTION_DISCOVERY_STARTED, Discovery Started...");
}
else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
Log.i("EEGdataCapture", "BluetoothAdapter.ACTION_DISCOVERY_FINISHED, Discovery finished.");
}
else
{
Log.i("EEGdataCapture", "BluetoothAdapter, ACTIOM is not supported, action ="+action);
}
}};
private void pairDevice(BluetoothDevice device) {
try {
Method method = device.getClass().getMethod("createBond", (Class[]) null);
method.invoke(device, (Object[]) null);
} catch (Exception e) {
e.printStackTrace();
}
}
private void unpairDevice(BluetoothDevice device) {
try {
Method method = device.getClass().getMethod("removeBond", (Class[]) null);
method.invoke(device, (Object[]) null);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected void onPause() {
super.onPause();
if ( StreamApiUtility.getBluetoothAdapter()!=null) {
StreamApiUtility.getBluetoothAdapter().cancelDiscovery();
}
if (mReceiver!=null)
{
try {
unregisterReceiver(mReceiver);
}
catch (IllegalArgumentException exc)
{
exc.printStackTrace();
}
}
}
@Override
protected void onResume()
{
super.onResume();
//filter to capture bluet events
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothDevice.ACTION_UUID);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
//register listener for bluet events before starting discovery again
registerReceiver(mReceiver, filter);
}
@Override
protected void onDestroy() {
super.onDestroy();
if (mReceiver!=null)
{
try {
unregisterReceiver(mReceiver);
}
catch (IllegalArgumentException exc)
{
exc.printStackTrace();
}
}
}
}

updated Manifest:

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

The BroadcastReciever’s BluetoothDevice.ACTION_FOUND is not being triggered/called although ACTION_DISCOVERY_STARTED OR ACTION_DISCOVERY_FINISHED are being called.

Help please???

Thanks

How to&Answers:

Your code seems ok. I guess you have the BLUETOOTH permission (otherwise you wouldn’t receive the ACTION_DISCOVERY_STARTED) but do you also have the ACCESS_COARSE_LOCATION permission ?

You need it to receive ACTION_FOUND :

ACTION_FOUND
Broadcast Action: Remote device discovered.
Requires BLUETOOTH and ACCESS_COARSE_LOCATION to receive.

Answer:

You need to perform a realtime-Permission check to ensure that Coarse Location is enabled before discovering any devices.
To do this, you should be targeting/minimum SDK 23+ in your build.gradle file.

if (mActivityContext.checkSelfPermission("android.permission.ACCESS_COARSE_LOCATION") == PackageManager.PERMISSION_GRANTED) { final BluetoothManager bluetoothManager = (BluetoothManager) mActivityContext.getSystemService(Context.BLUETOOTH_SERVICE); if (bluetoothManager != null) mBleAdapter = bluetoothManager.getAdapter(); 

Register Intent Filters here

 mBleAdapter.startDiscovery(); } else { mInterface.requestPermission(Manifest.permission.ACCESS_COARSE_LOCATION, mCoarsePermissionTag); } 

mInterface is my interface back to my MainActivity