Scan bluetooth devices not working on Android Things DP3 - bluetooth

Question

Scan Bluetooth Devices not working on Android Things DP3. Any idea/workaround? Not getting action BluetoothDevice.ACTION_FOUND.
I've added ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION permisssion due changes in Android 6.0 but still not working.
https://developer.android.com/about/versions/marshmallow/android-6.0-changes.html
Also android.permission.BLUETOOTH_ADMIN, android.permission.BLUETOOTH
I have checked, ACCESS_FINE_LOCATION or ACCESS_COARSE_LOCATION over Android >=6.0 needs runtime permission but it give an error due Android Things limitation.
private void checkPermission() {
List<String> permissionsList = new ArrayList<String>();
List<String> permissionsNeeded = new ArrayList<String>();
// app
permissionsList.add(Manifest.permission.ACCESS_FINE_LOCATION);
permissionsList.add(Manifest.permission.ACCESS_COARSE_LOCATION);
permissionsList.add(Manifest.permission.ACCESS_WIFI_STATE);
permissionsList.add(Manifest.permission.SET_TIME_ZONE);
// AndroidThingsLib
permissionsList.add(Manifest.permission.BLUETOOTH_ADMIN);
permissionsList.add(Manifest.permission.BLUETOOTH);
permissionsList.add(Manifest.permission.CHANGE_WIFI_STATE);
permissionsList.add(Manifest.permission.INTERNET);
permissionsList.add(Manifest.permission.ACCESS_NETWORK_STATE);
for (int i = 0; i < permissionsList.size(); i++){
if (checkSelfPermission(permissionsList.get(i)) == PackageManager.PERMISSION_GRANTED) {
permissionsNeeded.add(permissionsList.get(i));
updateDataLogs(SourceEnum.System, "GRANTED: " + permissionsList.get(i));
} else {
permissionsNeeded.add(permissionsList.get(i));
updateDataLogs(SourceEnum.Error, "NOT GRANTED: " + permissionsList.get(i));
}
}
if (permissionsList.size()>0){
requestPermissions(permissionsNeeded.toArray(new String[permissionsNeeded.size()]),5678);
}
}
#Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
if (requestCode == 5678){
for (int i = 0; i < permissions.length; i++){
updateDataLogs(SourceEnum.Error, permissions[i] + " result " + grantResults[i]);
}
}
}
private void enableBluetoothScan() {
updateDataLogs(SourceEnum.System, "enableBluetoothScan");
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
registerReceiver(mReceiver, filter);
BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (bluetoothAdapter.isEnabled()){
bluetoothAdapter.startDiscovery();
} else {
updateDataLogs(SourceEnum.Error, "Bluetooth Adapter not enabled");
}
}
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
updateDataLogs(SourceEnum.System, "DISCOVERY STARTED");
} else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
updateDataLogs(SourceEnum.System, "DISCOVERY FINISHED");
} else if (BluetoothDevice.ACTION_FOUND.equals(action)) {
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
updateDataLogs(SourceEnum.System, "NEW DEVICE " + device.getName());
}
}
}
};

Answer 1

As noted in the Platform Overview, runtime permissions granting is not supported on Android Things because the device may not have an interactive display to show the dialog. Instead, Android Things falls back on the install-time permissions model for all permissions requested in the manifest. This means calls to methods like requestPermissions() aren't necessary and won't help you.
Regarding issues encountered during the current preview, the following excerpt is from the Release Notes:
Dangerous permissions requested by apps are not granted until the next device reboot. This includes new app installs and new elements in existing apps.
For the time being, when your app requests dangerous permissions (like location permissions), you need to reboot the device after install (one-time) to have those permissions granted during boot.

Answer 2

Thanks to your explanation what you did already, I was able to conquer this issue. Because you did not mark the question as solved yet:
build.gradle (app; thanks to 1 and 2):
apply plugin: 'com.android.application'
android {
compileSdkVersion 24
<!-- update this to your version of the Android SDK Tools -->
buildToolsVersion "25.0.3"
defaultConfig {
minSdkVersion 24
}
}
dependencies {
<!-- update this to your version of Android Things -->
provided 'com.google.android.things:androidthings:0.4-devpreview'
}
AndroidManifest.xml (thanks to 1 and 2):
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package=" . . . ">
<!-- required for getState in startDiscovery -->
<uses-permission android:name="android.permission.BLUETOOTH"/>
<!-- required for startDiscovery -->
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<!-- required for the IntentFilter ACTION_FOUND -->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<!-- change to your label -->
<application android:label="Intel Edison">
<uses-library android:name="com.google.android.things"/>
<!-- change to the name of your Main Activity -->
<activity android:name=".HomeActivity">
<!-- Launch activity as default from Android Studio -->
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
<!-- Launch activity automatically on boot -->
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.IOT_LAUNCHER"/>
<category android:name="android.intent.category.DEFAULT"/>
</intent-filter>
</activity>
</application>
</manifest>
HomeActivity.java:
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothDevice.ACTION_NAME_CHANGED);
registerReceiver(mReceiverBT, filter);
BluetoothAdapter mBtAdapter = BluetoothAdapter.getDefaultAdapter();
boolean started = mBtAdapter.startDiscovery();
if (false == started) {
<!-- in that case, catch BluetoothAdapter.STATE_ON in the receiver and start the Bluetooth Discovery then -->
mBtAdapter.enable();
}
With this code, my app started right away after booting the Intel Edison board and was able to discover nearby Bluetooth devices. Notes:
On this board, Android Things requires 69 seconds (Developer Preview 4) or 82 seconds (Developer Preview 3) to start my app.
In logcat, I saw "Not granting permission android.permission.ACCESS_COARSE_LOCATION to package … because it was previously installed without". I found no way around that; reported in Issue 62514750.
Actually, you might not need any ‘dangerous’ permission at all – for example, I do nothing on ACTION_FOUND – because ACTION_NANE_CHANGED is fired always here in my scenarios; reported in Issue 62524160.