Develop Reference

Scan devices with bluetooth

I've copied the following code from Android documentation but doesn't discovery any device. Anyone know why?
public class MainActivity extends AppCompatActivity {
private BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
private TextView tvBoundedDevices;
private TextView tvDiscoveredDevices;
private IntentFilter intentFilter = new IntentFilter();
private BroadcastReceiver broadcastReceiver;
private ProgressDialog progressDialog;
private ArrayList<BluetoothDevice> bluetoothDevicesFound = new ArrayList<>();
private Set<BluetoothDevice> bluetoothDevicesBounded;
#Override
protected void onDestroy() {
unregisterReceiver(broadcastReceiver);
bluetoothAdapter.cancelDiscovery();
super.onDestroy();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tvBoundedDevices = findViewById(R.id.tvBoundedDevices);
tvDiscoveredDevices = findViewById(R.id.tvDiscoveredDevices);
intentFilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
intentFilter.addAction(BluetoothDevice.ACTION_FOUND);
intentFilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
switch (action){
case BluetoothAdapter.ACTION_DISCOVERY_STARTED:
progressDialog = ProgressDialog.show(MainActivity.this,"Attendere","Scan in corso");
break;
case BluetoothDevice.ACTION_FOUND:
bluetoothDevicesFound.add((BluetoothDevice) intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE));
break;
case BluetoothAdapter.ACTION_DISCOVERY_FINISHED:
if(progressDialog.isShowing())
progressDialog.dismiss();
break;
default:
Toast.makeText(context, "Action=" + action, Toast.LENGTH_LONG).show();
}
}
};
registerReceiver(broadcastReceiver,intentFilter);
}
public void turnBluetoothOn(View view){
if(!bluetoothAdapter.isEnabled()){
bluetoothAdapter.enable();
Toast.makeText(this,"Bluetooth attivato",Toast.LENGTH_SHORT).show();
}
}
public void turnBluetoothOff(View view){
if(bluetoothAdapter.isEnabled()){
bluetoothAdapter.disable();
Toast.makeText(this,"Bluetooth disattivato",Toast.LENGTH_SHORT).show();
}
}
public void scanDevices(View view){
turnBluetoothOn(null);
if(bluetoothAdapter.isDiscovering())
bluetoothAdapter.cancelDiscovery();
Toast.makeText(this, "Scansione " + (bluetoothAdapter.startDiscovery()?"":"non") + " avviata.", Toast.LENGTH_SHORT).show();
printDevices();
}
String toStamp = "";
private void printDevices(){
bluetoothDevicesBounded = bluetoothAdapter.getBondedDevices();
if(!bluetoothDevicesBounded.isEmpty()){
toStamp = "Dispositivi associati:\n";
for(BluetoothDevice b : bluetoothDevicesBounded){
toStamp += b.getName() + " | " + b.getAddress() + "\n";
}
tvBoundedDevices.setText(toStamp + "");
}
if(!bluetoothDevicesFound.isEmpty()){
toStamp = "Dispositivi trovati:\n";
for(BluetoothDevice b : bluetoothDevicesFound){
toStamp += b.getName() + " | " + b.getAddress() + "\n";
}
tvDiscoveredDevices.setText(toStamp + "");
}
}
Pastebin: https://pastebin.com/CnEBAtwt
What works:
- List of bounded devices
- Broadcast for "start discovery" and "end discovery"
What doesn't works:
- Discovery nearby devices
Thank you

You need to add one of the following permission to found devices:
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
or
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
If you are working on API 23 and higher you must ensure this permission is granted because it is a dangerous level permission.
Beginning in Android 6.0 (API level 23), users grant permissions to apps while the app is running, not when they install the app
See this guide to request permission.

Bluetooth:onReceive() and registerReceiver() these method never been called

I am developing an application for a Bluetooth client side, and inside this application has a listview that will list out all the connected devices. First, the application will check for the availability of the Bluetooth and then try to connect to another device(Server) , beside that, I initialised the intent filter in the manifest file.
Below is my code :
public class MainActivity extends AppCompatActivity {
ArrayAdapter<String> listAdapter;
ListView listView;
BluetoothAdapter mBluetoothAdapter;
Set<BluetoothDevice> bondedDevices;
private BluetoothSocket socket;
Intent discoverableIntent;
private BluetoothDevice remoteDevice;
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equalsIgnoreCase("android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED"))
{
Log.i("Connect", "Connecting.>>>>");
unregisterReceiver(this);
remoteDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
String Temp1 = remoteDevice.getName();
String Temp2 = remoteDevice.getAddress();
listAdapter.add(Temp1 + Temp2);
listView.setAdapter(listAdapter);
new Thread(reader).start();
}
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
IntentFilter intentFilter = new IntentFilter("com.example.jackpowell.bluetoothclient.ACTION_ACL_CONNECTED");
registerReceiver(mReceiver,intentFilter);
startDiscovery();
}
private void startDiscovery() {
mBluetoothAdapter.cancelDiscovery();
mBluetoothAdapter.startDiscovery();
}
public void init() {
listView = (ListView)findViewById(R.id.listView);
listAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,0);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
Toast.makeText(MainActivity.this, "Bluetooth is not supported in this device", Toast.LENGTH_SHORT).show();
finish();
} else {
if (!mBluetoothAdapter.isEnabled()) {
turnOnBluetooth();
}
}
bondedDevices = mBluetoothAdapter.getBondedDevices();
discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
startActivity(discoverableIntent);
}
private Runnable reader = new Runnable() {
#Override
public void run() {
try {
Log.i("Connect","Connecting...........");
android.util.Log.e("TrackingFlow", "Found: " + remoteDevice.getName());
UUID uuid = UUID.fromString("a60f35f0-b93a-11de-8a19-03002011c456");
socket = remoteDevice.createRfcommSocketToServiceRecord(uuid);
socket.connect();
} catch (Exception e) {
e.printStackTrace();
}
}
};
private void turnOnBluetooth() {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_CANCELED) {
Toast.makeText(getApplicationContext(), "Bluetooth must be enabled to continue", Toast.LENGTH_SHORT).show();
finish();
}
}
#Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(mReceiver);
}
}
my manifest:
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<receiver android:name="bluetoothclient">
<intent-filter>
<action android:name="android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED" />
</intent-filter>
</receiver>
The problem now is onReceive() and registerReceiver() these method never been called, or maybe it already called, I just dont get it. If these method were called, the log cat should be displaying the log command. Why are these method never been called? thank you in advance!

The action name is "android.bluetooth.device.action.ACL_CONNECTED" (to use in manifest) or BluetoothDevice.ACTION_ACL_CONNECTED (to use in code, for intent filter). Action names in your code seem wrong.
Note, to register receiver in manifest the receiver name should be public class based on BroadcastReceiver, not sure what is the "bluetoothclient" meaning in the code above (you didn't show the receiver code).
Usually you don't need both manifest receiver and intent filter receiver in activity, one may be sufficient. The main difference is that manifest receiver can be independent from activity life cycle and receive even when activity is not running.
Try to listen also for ACTION_FOUND (per documentation after startDiscovery you'll receive BluetoothDevice.ACTION_FOUND) and others and try to reduce into minimal example. You need also check result of startDiscovery() which can return false on failure.
Here is slightly modified sample from Discovering devices section:
#Override
protected void onCreate(Bundle savedInstanceState) {
...
// Register for broadcasts
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
registerReceiver(mReceiver, filter);
...
if(!mBluetoothAdapter.startDiscovery()){
Log.e("Bluetooth", "discovery error");
}
}
// Create a BroadcastReceiver for bluetooth actions
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.i("Bluetooth", "got action " + action);
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Discovery has found a device. Get the BluetoothDevice
// object and its info from the Intent.
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
String deviceName = device.getName();
String deviceHardwareAddress = device.getAddress(); // MAC address
Log.i("Bluetooth", "got device " + deviceName );
}
}
};
#Override
protected void onDestroy() {
super.onDestroy();
...
// Don't forget to unregister the ACTION_FOUND receiver.
unregisterReceiver(mReceiver);
}
Also note, per this question/answer, on some devices discovery does not always work as expected and there is a need for workarounds.
By the way, did you check the logcat for other errors, for example denied permissions etc.? You may try to enable location and add location permission.
Here is a working sample to display all devices:
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.testbluetooth"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="17"
android:targetSdkVersion="21" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
MainActivity.java
package com.example.testbluetooth;
import android.app.Activity;
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.util.Log;
import android.view.ViewGroup.LayoutParams;
import android.widget.FrameLayout;
import android.widget.TextView;
public class MainActivity extends Activity {
TextView textView;
StringBuilder text = new StringBuilder();
private void addLine(String line)
{
Log.i(getClass().getSimpleName(), line);
text.append("[bluetooth] ").append(line).append('\n');
if(textView!=null)
textView.setText(text);
}
BluetoothAdapter mBluetoothAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.activity_main);
FrameLayout content = new FrameLayout(this);
textView = new TextView(this);
content.addView(textView, new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
addLine("onCreate");
setContentView(content);
// Register for broadcasts
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
registerReceiver(mReceiver, filter);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
for(BluetoothDevice pairedDevice : mBluetoothAdapter.getBondedDevices())
{
addLine("got paired device " + pairedDevice.getName());
}
if(!mBluetoothAdapter.startDiscovery()){
addLine("ERROR: discovery error");
}
else
{
addLine("starting discovery");
}
}
// Create a BroadcastReceiver for bluetooth actions
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
addLine("got action " + action);
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Discovery has found a device. Get the BluetoothDevice
// object and its info from the Intent.
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
String deviceName = device.getName();
//String deviceHardwareAddress = device.getAddress(); // MAC address
addLine("got device " + deviceName );
}
}
};
}

How to receive USB connection status broadcast?

I am trying to detect USB connection in my app, that is, whether or not USB is connected to device.
It's being tested on Marshmallow 6.0.1 (sdk23)
But I'm unable to receive the broadcast actions ACTION_USB_DEVICE_ATTACHED or ACTION_USB_DEVICE_DETACHED..
I tried using both the dynamic way and the AndroidManifest.xml way, neither worked..
Here's my code:
AndroidManifest.xml :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.gokulnc.blah_blah"
android:installLocation="auto"
android:versionCode="15"
android:versionName="1.5.1">
<uses-feature android:name="android.hardware.usb.host" />
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="23" />
<android:uses-permission android:name="android.permission.USB_PERMISSION" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:vmSafeMode="false">
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:theme="#style/DrawerTheme">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<receiver android:name="mUsbReceiver">
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
</intent-filter>
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_DETACHED" />
</intent-filter>
</receiver>
</activity>
</application>
</manifest>
MainActivity.java :
public class MainActivity extends AppCompatActivity {
BroadcastReceiver mUsbReceiver;
public void onCreate(Bundle savedInstanceState) {
.....
setBroadcastReceivers();
}
void setBroadcastReceivers() {
//Reference: http://www.codepool.biz/how-to-monitor-usb-events-on-android.html
mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.d(LOG_TAG, "Received Broadcast: "+action);
if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action) || UsbManager.ACTION_USB_ACCESSORY_ATTACHED.equals(action)) {
updateUSBstatus();
Log.d(LOG_TAG, "USB Connected..");
} else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action) || UsbManager.ACTION_USB_ACCESSORY_DETACHED.equals(action)) {
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (device != null) {
updateUSBstatus();
}
Log.d(LOG_TAG, "USB Disconnected..");
}
}
};
IntentFilter filter = new IntentFilter();
filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
//filter.addAction(UsbManager.ACTION_USB_ACCESSORY_ATTACHED);
//filter.addAction(UsbManager.ACTION_USB_ACCESSORY_DETACHED);
registerReceiver(mUsbReceiver , filter);
Log.d(LOG_TAG, "mUsbReceiver Registered");
}
#Override
public void onResume() {
super.onResume();
Log.d(LOG_TAG, "App Resumed..");
//Refernce: https://stackoverflow.com/questions/18015656/cant-receive-broadcast-intent-of-usbmanager-action-usb-device-attached-usbmanag
Intent intent = getIntent();
if (intent != null) {
if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_ATTACHED)) {
Toast.makeText(getApplicationContext(), "Attached", Toast.LENGTH_SHORT).show();
} else if(intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_DETACHED)) {
Toast.makeText(getApplicationContext(), "Detached", Toast.LENGTH_SHORT).show();
}
}
}
}
I also checked this answer: Can't receive broadcast Intent of UsbManager.ACTION_USB_DEVICE_ATTACHED/UsbManager.ACTION_USB_DEVICE_DETACHED, but it didn't help..
Can someone please point out where I'm wrong??

Maybe the reason it doesn't work is that since Android 6.0, the default USB mode is Charging and, maybe ACTION_USB_DEVICE_ATTACHED doesn't get fired up when connected in that mode..
Instead, now I have another solution:
String usbStateChangeAction = "android.hardware.usb.action.USB_STATE";
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.d(LOG_TAG, "Received Broadcast: "+action);
if(action.equalsIgnoreCase(usbStateChangeAction)) { //Check if change in USB state
if(intent.getExtras().getBoolean("connected")) {
// USB was connected
} else {
// USB was disconnected
}
}
}
That is, the broadcast android.hardware.usb.action.USB_STATE is sent whenever there is a toggle in the USB state.
Unlike android.hardware.usb.action.USB_DEVICE_ATTACHED which is broadcasted only when something like a MTP mode is enable, android.hardware.usb.action.USB_STATE is broadcasted whenever it detects an USB connection that's capable of connecting to a host (say computer), irrespective of its current USB Mode like Charging, MTP or whatever.. (it's called USB config to be more precise)

Here the perfect steps to check that external usb connection occur or not in android activity. Just Follow the steps one by one.
In Android Manifest file:
<uses-feature android:name="android.hardware.usb.host" />
<uses-permission android:name="android.permission.USB_PERMISSION" />
Inside your USB checking Activity Tag:
<activity android:name=".USBEnabled">
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
</intent-filter>
<meta-data
android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
android:resource="#xml/device_filter" />
</activity>
Inside your connectivity checking USBEnabled class :
public class USBEnabled extends AppCompatActivity {
private static final String TAG = "UsbHost";
TextView mDeviceText;
Button mConnectButton;
UsbManager mUsbManager;
UsbDevice mDevice;
PendingIntent mPermissionIntent;
private static final int REQUEST_TYPE = 0x80;
private static final int REQUEST = 0x06;
private static final int REQ_VALUE = 0x200;
private static final int REQ_INDEX = 0x00;
private static final int LENGTH = 64;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_usbenabled);
mDeviceText = (TextView) findViewById(R.id.text_status);
mConnectButton = (Button) findViewById(R.id.button_connect);
mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
}
#Override
protected void onRestart() {
super.onRestart();
recreate();
}
#Override
protected void onResume() {
super.onResume();
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver, filter);
updateDeviceList();
}
#Override
protected void onPause() {
super.onPause();
unregisterReceiver(mUsbReceiver);
}
public void onConnectClick(View v) {
if (mDevice == null) {
return;
}
mUsbManager.requestPermission(mDevice, mPermissionIntent);
}
private static final String ACTION_USB_PERMISSION = "com.android.recipes.USB_PERMISSION";
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (ACTION_USB_PERMISSION.equals(action)) {
UsbDevice device = (UsbDevice) intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)
&& device != null) {
getDeviceStatus(device);
} else {
Log.d(TAG, "permission denied for device " + device);
}
}
}
};
private void getDeviceStatus(UsbDevice device) {
UsbDeviceConnection connection = mUsbManager.openDevice(device);
byte[] buffer = new byte[LENGTH];
connection.controlTransfer(REQUEST_TYPE, REQUEST, REQ_VALUE, REQ_INDEX,
buffer, LENGTH, 2000);
connection.close();
}
private void updateDeviceList() {
HashMap<String, UsbDevice> connectedDevices = mUsbManager
.getDeviceList();
if (connectedDevices.isEmpty()) {
mDevice = null;
mDeviceText.setText("No Devices Currently Connected");
mConnectButton.setEnabled(false);
} else {
for (UsbDevice device : connectedDevices.values()) {
mDevice = device;
}
mDeviceText.setText("USB Device connected");
mConnectButton.setEnabled(true);
}
}}
Inside your class xml file :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="#+id/button_connect"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="onConnectClick"
android:text="Connect" />
<TextView
android:id="#+id/text_status"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="22dp" />
<TextView
android:id="#+id/text_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="22dp" />
</LinearLayout>
Now create a new resource directory called xml and create new xml file called device_filter.xml with the following code.
<?xml version="1.0" encoding="utf-8"?>
<resources>
<usb-device />
</resources>
Debug and run the application, it will show external usb device connectivity status without any error. I hope you will get output for your scenario.
Enjoy!!

Having Bluetooth problems with my app

I'm developing an app for a project. It uses bluetooth. I followed the steps for for setting up bluetooth from google's developer page. I reached the phase where i enable discoverability. The problem is that I want to display the devices in a listview , and they don't show up. Maybe someone can point out my clumsiness as i can't see the problem.
public class MainActivity extends AppCompatActivity {
private final static int REQUEST_ENABLE_BT = 1;
Set<BluetoothDevice> pairedDevices;
ArrayAdapter<String> deviceAdapter;
ArrayList<String> list;
ListView listView;
BroadcastReceiver mReceiver;
Intent discoverableIntent;
IntentFilter intentFilter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.devices);
list = new ArrayList<>();
deviceAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, list);
listView.setAdapter(deviceAdapter);
BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (bluetoothAdapter == null)
Toast.makeText(this, "Bluetooth is not supported!", Toast.LENGTH_SHORT).show();
else {
if (!bluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
}
if (bluetoothAdapter != null) {
pairedDevices = bluetoothAdapter.getBondedDevices();
}
if (pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
deviceAdapter.add(device.getName() + "\n" + device.getAddress());
}
}
mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
deviceAdapter.add(device.getName() + "\n" + device.getAddress());
Log.d("BT", device.getName() + "\n" + device.getAddress());
}
}
};
intentFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver, intentFilter);
if (bluetoothAdapter.isDiscovering()) {
bluetoothAdapter.cancelDiscovery();
}
bluetoothAdapter.startDiscovery();
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
}
#Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(mReceiver);
}
}
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.szili.bluetoothclient.MainActivity">
<ListView
android:id="#+id/devices"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</ListView>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.szili.bluetoothclient">
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- ATTENTION: This was auto-generated to add Google Play services to your project for
App Indexing. See https://g.co/AppIndexing/AndroidStudio for more information. -->
<meta-data
android:name="com.google.android.gms.version"
android:value="#integer/google_play_services_version" />
</application>
</manifest>

You forgot to scan devices:
// Create a BroadcastReceiver for ACTION_FOUND
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// Add the name and address to an array adapter to show in a ListView
mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}
}
};
// Register the BroadcastReceiver
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver, filter); // Don't forget to unregister during onDestroy
To start discovering devices, simply call startDiscovery()
From: http://developer.android.com/intl/es/guide/topics/connectivity/bluetooth.html

After some research I was able to figure out what the problem was. Basically with Android Marshmallow i needed to give Location permission to my app else it couldn't scan for nearby devices.

Android - Issues with using Library Activity in another Application

I have made an application that allows many-to-one communication using Bluetooth and it is working perfectly fine. Now, i wanted to use the service of the application in another application (e.g. Discovering Devices, Connecting to Device). So, I marked my project as library and added it as library in my new project. However, when i call the Discovering Device Activity (Available in library) from the application, the activity starts, but it doesn't discovers the devices ? Can someone help on this ?
I have included all the library project activity and permissions in my app's manifest.
Here is the sample code for the same -
In Library -
This is how the DeviceListActivity Looks like -
`
public class DeviceListActivity extends Activity{
String insecure="8ce255c0-200a-11e0-ac64-0800200c9a66";
private int flag=0;
int flag_toast=0;
ArrayList<Pair<String,String>> x=new ArrayList<Pair<String,String>>();
private static final String TAG = "DeviceListActivity";
ArrayList<String> temp=new ArrayList<String>();
Map<String, String> services = new HashMap<String, String>();
/**
* Return Intent extra
*/
public static String EXTRA_DEVICE_ADDRESS = "device_address";
/**
* Member fields
*/
private BluetoothAdapter mBtAdapter;
/**
* Newly discovered devices
*/
ImageView animation;
private ArrayList<BluetoothDevice> btDeviceList = new ArrayList<BluetoothDevice>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Setup the window
// requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
setContentView(R.layout.activity_device_list);
// Set result CANCELED in case the user backs out
setResult(Activity.RESULT_CANCELED);
// Initialize the button to perform device discovery
animation=(ImageView)findViewById(R.id.imageAnimation);
/*scanButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
doDiscovery();
v.setVisibility(View.GONE);
}
});*/
// Initialize array adapters. One for already paired devices and
// one for newly discovered devices
//ArrayAdapter<String> pairedDevicesArrayAdapter =new ArrayAdapter<String>(this, R.layout.device_name);
//mNewDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name);
//Register for broadcasts when a device is discovered
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothDevice.ACTION_UUID);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
registerReceiver(mReceiver, filter);
/* this.registerReceiver(mReceiver, filter);
// Register for broadcasts when discovery has finished
filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.registerReceiver(mReceiver, filter);
*/
// Get the local Bluetooth adapter
mBtAdapter = BluetoothAdapter.getDefaultAdapter();
animation.setBackgroundResource(R.drawable.animation);
doDiscovery();
}
#Override
protected void onDestroy() {
super.onDestroy();
// Make sure we're not doing discovery anymore
if (mBtAdapter != null) {
mBtAdapter.cancelDiscovery();
}
// Unregister broadcast listeners
this.unregisterReceiver(mReceiver);
}
/**
* Start device discover with the BluetoothAdapter
*/
public void doDiscovery() {
Log.d(TAG, "doDiscovery()");
// If we're already discovering, stop it
if (mBtAdapter.isDiscovering()) {
mBtAdapter.cancelDiscovery();
}
// Request discover from BluetoothAdapter
mBtAdapter.startDiscovery();
}
private void connect_automatic(String name){
flag++;
Log.d(name,"Called " + Integer.toString(flag)+" times");
Log.d("Flag is = ",Integer.toString(flag));
int i,j;
for(i=0;i<x.size();i++){
for (j=i+1;j<x.size();j++)
if (x.get(i).getFirst().equals(x.get(j).getFirst())==true && x.get(i).getSecond().equals(x.get(j).getSecond())==true)
x.remove(j);
}
for(i=0;i<x.size();i++){
Log.d("Found "+x.get(i).getFirst(),x.get(i).getSecond());
}
Log.d("Size =",Integer.toString(x.size()));
if (x.size()>=1){
Log.d("Size is =",Integer.toString(x.size()));
String address = x.get(0).getFirst();
if (flag_toast==0)
Toast.makeText(DeviceListActivity.this, "Merchant Found", Toast.LENGTH_SHORT).show();
flag_toast++;
Log.d("Connecting to ",x.get(0).getFirst());
// Create the result Intent and include the MAC address
Intent intent = new Intent();
intent.putExtra(EXTRA_DEVICE_ADDRESS, address);
// Set result and finish this Activity
setResult(Activity.RESULT_OK, intent);
finish();
}
}
/**
* The BroadcastReceiver that listens for discovered devices and changes the title when
* discovery is finished
*/
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
flag++;
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// If it's already paired, skip it, because it's been listed already
//mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());
btDeviceList.add(device);
// When discovery is finished, change the Activity title
}
else
{
Log.d("Action=",action.toString());
if(BluetoothDevice.ACTION_UUID.equals(action)) {
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
Parcelable[] uuidExtra = intent.getParcelableArrayExtra(BluetoothDevice.EXTRA_UUID);
if(uuidExtra!=null)
for (int i=0; i<uuidExtra.length; i++) {
if(uuidExtra[i].toString().length()>0){
Log.d("\n Device: " + device.getName() + ", " + device, ", Service: " + uuidExtra[i].toString());
// services.put(device.getName(), uuidExtra[i].toString());
//flag=btDeviceList.size();
if (/*uuidExtra[i].toString().equals(secure)==true ||*/ uuidExtra[i].toString().equals(insecure)==true){
Pair<String,String> t=new Pair<String, String>(device.getAddress(), uuidExtra[i].toString());
x.add(t);
}
//connect_automatic();
}
}
Log.d("Device List =",Integer.toString(flag));
connect_automatic(device.getName());
//Log.d("Boolean",Boolean.toString(services.isEmpty()))
}
else
{
if(BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
Log.d("Discovery","Started...");
}
else
{
if(BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
Log.d("Discover","Finished");
//setProgressBarIndeterminateVisibility(false);
Iterator<BluetoothDevice> itr = btDeviceList.iterator();
while (itr.hasNext()) {
// Get Services for paired devices
BluetoothDevice device = itr.next();
temp.add(device.getName());
Log.d("ok","Getting Services for " + device.getName() + ", " + device);
if(!device.fetchUuidsWithSdp()) {
Log.d("!ok","SDP Failed for " + device.getName());
}
else{
Log.d("SDP Passed for ",device.getName());
}
}
//connect_automatic();
}
}
}
}
}
};}`
And here is how i call it in my new application -
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter != null)
{
ensureDiscoverable();
Intent intent = new Intent(this, DeviceListActivity.class);
startActivityForResult(intent, REQUEST_CONNECT_DEVICE_INSECURE);
}
}