Develop Reference

bluetoothAdapter.enable(); shows Bluetooth enable prompt without intent ACTION_REQUEST_ENABLE in some devices

I would like to enable bluetooth with my app without user interaction, the prompt does not appear on my devices - Android 7, 8 & 9, and my friend's Android 10. But it appears in my work colleague's devices (Android 10).
I used the following permissions
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
And used the following Bluetooth Adaptor methods.
bluetoothAdapter.enable();
bluetoothAdapter.disable();
I have no intent ACTION_REQUEST_ENABLE or ACTION_REQUEST_DISABLE in my source code.
Am I missing some permissions or methods?
Or is this an environment problem?
Any advise on how should I handle this would be much appreciated.
Thank you.

bluetoothAdapter.enable() will directly run com.android.settings/.bluetooth.RequestPermissionHelperActivity, and you should listen for ACTION_STATE_CHANGED yourself.
I think use the BluetoothAdapter.ACTION_REQUEST_ENABLE is a better way, which will first run com.android.settings.bluetooth.RequestPermissionActivity and then RequestPermissionHelperActivity. RequestPermissionActivity will listen for ACTION_STATE_CHANGED, while your app only need the result code of Activity.RESULT_OK.
private boolean ensureBluetoothEnabled() {
if(((BluetoothManager) Objects.requireNonNull(getSystemService(Context.BLUETOOTH_SERVICE)))
.getAdapter().isEnabled()) {
return true;
} else {
Intent btIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
btIntent.putExtra(Intent.EXTRA_PACKAGE_NAME, Constants.PACKAGE);
startActivityForResult(btIntent, REQUEST_CODE_BL_OPEN);
return false;
}
}

BLE Scan not working

I am a beginner working on a BLE scanner using Google's sample code: https://github.com/googlesamples/android-BluetoothLeGatt
Currently, the code is not able to detect any devices. This post says that this is because of location services being disabled or not being explicitly asked for on runtime. I have already included the required permissions in my Manifest.
I have added a few lines of code, which I think should work.
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getActionBar().setTitle(R.string.title_devices);
mHandler = new Handler();
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
finish();
}
// Initializes a Bluetooth adapter. For API level 18 and above, get a reference to
// BluetoothAdapter through BluetoothManager.
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
// Checks if Bluetooth is supported on the device.
if (mBluetoothAdapter == null) {
Toast.makeText(this, R.string.error_bluetooth_not_supported, Toast.LENGTH_SHORT).show();
finish();
return;
}
// Quick permission check
int permissionCheck = this.checkSelfPermission("Manifest.permission.ACCESS_FINE_LOCATION");
permissionCheck += this.checkSelfPermission("Manifest.permission.ACCESS_COARSE_LOCATION");
if (permissionCheck != 0) {
this.requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION}, 1001); //Any number
}
}
I think the quick permission check I have added should work, but the app still doesn't seem to be detecting any devices.

I have met the same case that you are facing. If you are using android 6.0 or greater than. You must request location permission at runtime. After get Bluetooth Adapter, let's insert a code line as below to request location permission. When your app run, a dialog will be showed to ask whether you agree to shared your location.
ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION}, 1001);
Let response my answer if this is not correct answer for you question, I will delete immediately.

onscannerregistered status =133
This might be because of the below reason.
1)Location Permission not given in Appication.
2)When Connecting to the Devies stop the scan and then connect to devices.
3)Scanning should not happen when we are reading/writing Data to Devices.
Make sure the scan is stopped
4)If Frist scan is started should wait until the scan is finished.Then start the second scan.
5)Scanning multiple times without waiting for the previous scan to finish might result in couldn't find the scan call-back.
Try fast BLE Library it s more effective the Google BLE library available.

How to get available Hotspot network and show on list in android

I am making a android game in which user can play game using hotspot connectivity like the share it app connect the two user using hotspot.I searched on google but they only show list of wifi network but i only want to show the available hotspot in near by.Please help me guys.I am stuck in this from three days.

You need to create a BroadcastReceiver to listen for Wifi scan results:
private final BroadcastReceiver mWifiScanReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context c, Intent intent) {
if (intent.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
List<ScanResult> mScanResults = mWifiManager.getScanResults();
// add your logic here
}
}
}
In onCreate() you would assign mWifiManager and initiate a scan:
mWifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
registerReceiver(mWifiScanReceiver,
new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
mWifiManager.startScan();
getScanResults() will return data only if you have appropriate permissions. For this, add one of the following two lines to your AndroidManifest.xml:
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
Also note that in API 23+, permissions must be requested at runtime. (For a lab environment, you can also grant permissions manually in Settings instead—less coding required, but not recommended for an end-user app.)
Note that the code which handles your scan results would run every time a new scan result is available, updating the result.

In Marshmallow broadcast is not working with action android.intent.action.proximity_sensor

In Marshmallow this code is not working with GearVR. Activity.onResume() code
IntentFilter intentFilter = new IntentFilter("android.intent.action.proximity_sensor");
mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
if(intent.getType().equals("1"))
{
Log.v(LOGTAG,"headset mounted");
}
else
{
Log.v(LOGTAG,"headset unmounted");
}
}
};
this.registerReceiver(mReceiver, intentFilter);
}
this is used to detect GearVR mounted and unmounted.
It was working in S6 Lollipop.
Probably this is bug in Marshmallow 6.0.1 link.
Any workaround this problem? related links link1 link2
Please share anything that help me in detecting GearVr mount and unmount

Android 6.0 is now using Doze mode to minimize the use of battery. So this Doze mode not allows the system wakups again and again. There should me Minimum of 9 mins gap should be there between two consecutive wakeups. See official documentation for detail.Cleck here

Can I turn on WiFi-Direct from code? on API-16 (Android 4.2.2)

I am developing an application with NFC and wifi direct. I get the MAC address using NFC and the Wifi Direct to transfer data. I call discoverpeers() and could get success. But there is no callback WIFI_P2P_PEERS_CHANGED_ACTION, the callback comes only when I go to settings and the select wifidirect.
This was discussed in the other question
Can I turn on WiFi-Direct from code? on Android API-14 (ICS)
"I'd like to add that WiFi direct on JB and above (at least on AOSP) is not active all the time - it only appears to be. If you look at listeners for WiFi direct, it turns itself off after some time. It turns itself back on if you open the wifi direct menu, however. You might have to have the host do a peer search or initialize itself in order to be able to be found. Likely a battery saving trick. I have also found that it's blocking, since as it accepts a connection, the entire system will lock up and fail to connect sometimes. (The system invitation) – Mgamerz "
Can anyone suggest the solution for the problem WIFI_P2P_PEERS_CHANGED_ACTION callback is not got and can get only when manually go to settings->wifi->tap on wifidirect
I used two devices Samsung galaxy nexus and nexus 7 both running on 4.2.2

There is no available API to enable wifiP2P but you can invoke method "enableP2p" from android settings 4.0.1
WifiP2pManager manager = (WifiP2pManager) getActivity().getSystemService(Context.WIFI_P2P_SERVICE);
Channel channel = manager.initialize(getActivity(), getActivity().getMainLooper(), null);
try {
Method method1 = manager.getClass().getMethod("enableP2p", Channel.class);
method1.invoke(manager, channel);
//Toast.makeText(getActivity(), "method found",
// Toast.LENGTH_SHORT).show();
} catch (Exception e) {
//Toast.makeText(getActivity(), "method did not found",
// Toast.LENGTH_SHORT).show();
}
To disable wifiP2P use this method
Method method1 = manager.getClass().getMethod("disableP2p", Channel.class);

Not from code. The user has to. That's why the demo has the link to wifi settings in the action bar.
When you call manager.discoverPeers(channel, new WifiP2pManager.ActionListener()
define onFailure and look at the reasonCode. If it's 0, then either the Wifi or WiFi direct is off.
If you look at the WiFi Direct demo app, the WifiDirectBroadcast Reciever, this piece of code looks at whether p2p is enabled specifically
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {
// UI update to indicate wifi p2p status.
int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
// Wifi Direct mode is enabled
activity.setIsWifiP2pEnabled(true);
} else {
activity.setIsWifiP2pEnabled(false);
activity.resetData();
}
Then when discover peers is called it looks at the variable set by setIsWifiP2pEnabled

thanks user3093354. to continue with your solution, in order to disable the p2p you have to invoke:
Method method1 = manager.getClass().getMethod("disableP2p", Channel.class);

//Try this it may be help you
WifiManager wifiManager = (WifiManager)this.getSystemService(this.WIFI_SERVICE);
wifiManager.setWifiEnabled(true); //True - to enable WIFI connectivity .
//False -disable WIFI connectivity.
//add this permissions in Manifest file :
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"/>

You can load the wifi driver from a command prompt with the desired concurrency level if you are rooted:
/system/bin/insmod /system/lib/modules/wlan.ko con_mode=3
These are the values:
typedef enum
{
VOS_STA_MODE=0,
VOS_STA_SAP_MODE=1,
VOS_P2P_CLIENT_MODE,
VOS_P2P_GO_MODE,
VOS_MONITOR_MODE,
VOS_FTM_MODE = 5,
VOS_IBSS_MODE,
VOS_P2P_DEVICE_MODE,
VOS_MAX_NO_OF_MODE
} tVOS_CON_MODE;
This is for an Atheros card.