Develop Reference

Bluetooth start discovery not giving results

This is my first app in Android. I am very new to Android and Java. I am kind of expert in iOS/ObjC though. I am learning by doing. So I jumped straight into making an app to connect to a bluetooth device. First step is of course to get a list of the bluetooth device available in range.
Here is my manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest...>
<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 ...
Here is my Activity code:
private BluetoothAdapter btAdapter;
#Override
public void onDestroy() {
super.onDestroy();
// Unregister broadcast listeners
unregisterReceiver(mReceiver);
}
/*------------- ON CREATE ------------------------------*/
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter == null) {
System.out.println ("Bluetooth non support");
} else {
System.out.println ("Bluetooth initialized");
}
IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mReceiver, filter);
IntentFilter filterDevice = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver, filterDevice);
if (btAdapter.isEnabled()) {
String mydeviceaddress = btAdapter.getAddress();
String mydevicename = btAdapter.getName();
String status = mydevicename + " : " + mydeviceaddress;
System.out.println(status);
System.out.println ("Start discover");
btAdapter.startDiscovery();
} else {
System.out.println ("Not enabled");
Intent enableBT = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBT, 1);
}
}
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (action.equals(BluetoothAdapter.ACTION_STATE_CHANGED)) {
final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE,
BluetoothAdapter.ERROR);
switch (state) {
case BluetoothAdapter.STATE_OFF:
System.out.println("1");
break;
case BluetoothAdapter.STATE_TURNING_OFF:
System.out.println("2");
break;
case BluetoothAdapter.STATE_ON:
System.out.println("3");
// SCAN HERE
btAdapter.startDiscovery();
break;
case BluetoothAdapter.STATE_TURNING_ON:
System.out.println("4");
break;
}
}
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
System.out.println(device.getName() + "\n" + device.getAddress());
} else {
System.out.println("What de fuq");
}
}
};
I turned on bluetooth on my android phone, and then running the app shows that log:
Bluetooth initialized
Start discover
And thats all. Other logs are not printing out. Any idea why? My code seems perfect idk.
EDIT: Screenshot of the Bluetooth module HC-05 being detected by Android.

The other devices may not be in discoverable mode. Make sure they are discoverable.

If your other device is a bluetooth module, in your case Arduino, right?
If so, check this tutorial describing connection between Android device and HC05 module.
bthc-05 to android tutorial
Also, based on this official sample: google sample - bluetooth chat
Alternatively, you could also have the following method that makes your device discoverable. And install it on two phones. Then you should be able to discover the phones on each other atleast.
protected void makeDiscoverable(){
// Make local device discoverable
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, DISCOVERABLE_DURATION);
startActivityForResult(discoverableIntent, DISCOVERABLE_BT_REQUEST_CODE);
}
Maybe these help!

Bluetooth OnReceive Method Doesn't Get Called

I'm trying to make an android app which has some issues about Bluetooth. I simply enable Bluetooth, find devices, connect one of the devices, send & receive data. First thing is done. But in second, there are some problems. I make a Broadcast Receiver to discover devices nearby my phone. But OnReceive method doesn't get called. The weird thing is, it was getting called at first and I was able to see devices nearby. Then something that I cannot figure out happened and now OnReceive method doesn't get called. I've searched topics about these but none of them could solve my problem. MyDevice and MyAdapter are my own classes to show Bluetooth devices in listview with my own layout. Here is my code:
public class FoundDevicesActivity extends AppCompatActivity {
BluetoothAdapter bluetoothAdapter;
ListView foundedDevicesListView;
MyDeviceAdapter deviceAdapter;
List<MyDevice> foundedDevicesList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_found_devices);
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
foundedDevicesListView = (ListView) findViewById(R.id.foundDevicesListview);
if (bluetoothAdapter.isDiscovering()) {
bluetoothAdapter.cancelDiscovery();
}
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.registerReceiver(receiver, filter);
bluetoothAdapter.startDiscovery();
deviceAdapter = new MyDeviceAdapter(this, foundedDevicesList);
foundedDevicesListView.setAdapter(deviceAdapter);
}
private final BroadcastReceiver receiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
Toast.makeText(FoundDevicesActivity.this, "Discovery is started !!", Toast.LENGTH_SHORT).show();
Log.d("Found Devices Activity", "Discovery is started !!");
} else if (BluetoothDevice.ACTION_FOUND.equals(action)) {
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
MyDevice dvc = new MyDevice();
if (device.getName().equals(null)) {
dvc.name = "UNDEFINED NAME";
} else {
dvc.name = device.getName();
}
if(device.getAddress().equals(null)) {
dvc.address = "UNDEFINED ADDRESS";
} else {
dvc.address = device.getAddress();
}
foundedDevicesList.add(dvc);
} else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
bluetoothAdapter.cancelDiscovery();
Toast.makeText(FoundDevicesActivity.this, "Discovery is finished !!", Toast.LENGTH_SHORT).show();
Log.d("Found Devices Activity", "Discovery is finished !!");
}
}
};
}
Any idea ?

Android: Broadcast Receiver does not receive BluetoothDevice.ACTION_ACL_CONNECTED on restarting the application

I want my app to auto-connect to already connected bluetooth device on restarting the app. Below is procedure I am performing:-
[Initially] Bluetooth device is 'ON': Then on starting the app.
[Behavior]--> Bluetooth device gets paired and connected successfully ( Intent 'ACTION_ACL_CONNECTED' is received)
Bluetooth device is 'ON': Closed the app, then started the app again.
[Behavior]--> Even though it is connected as displayed on Bluetooth setting, and Broadcast Receiver does not receive Intent 'ACTION_ACL_CONNECTED'.
Note:- On closing the app, it does not disconnect the bluetooth connection.
So, on successful connection app straightaway goes to the HomeScreen. Otherwise, the app goes to a screen having button that takes it to Bluetooth setting(onClickListener present in the code below)
I am new to android development, so I really don't know where am I going wrong. I looked up the solutions for similar issues and applied them, but to no effect.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_index);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_ACL_CONNECTED);
registerReceiver(mReceiver, filter);
IntentFilter filter1 = new IntentFilter(BluetoothDevice.ACTION_ACL_DISCONNECTED);
this.registerReceiver(mReceiver, filter1);
m_app = (BtApp) getApplication();
imagebt = (ImageView) this.findViewById(R.id.imagebt);
imagebt.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
final Toast tag = Toast.makeText(getApplicationContext(), "Connect to device", Toast.LENGTH_LONG);
tag.show();
new CountDownTimer(1000, 1000)
{
public void onTick(long millisUntilFinished) {tag.show();}
public void onFinish() {
//tag.show();
}
}.start();
if(mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()){
mBluetoothAdapter.startDiscovery();
}
Intent intentBluetooth = new Intent();
intentBluetooth.setAction(android.provider.Settings.ACTION_BLUETOOTH_SETTINGS);
startActivity(intentBluetooth);
}
});
}
private BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if ( BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)) {
m_app.m_main.setupCommPort();
device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
m_app.m_device = device;
isconnected = true;
new Timer().schedule(new TimerTask() {
#Override
public void run() {
if ( m_app.m_main.m_BtService != null && m_app.m_main.m_BtService.getState() != BluetoothRFCommService.STATE_CONNECTED ) {
m_app.m_main.m_BtService.connect(device, false);
}
}
}, 3500);
} else if ( BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action) ) {
isconnected = false;
m_app.m_main.tabHost.setCurrentTab(0);
}
}
};
#Override
protected void onStop()
{
unregisterReceiver(mReceiver);
super.onStop();
}

You won't get BluetoothDevice.ACTION_ACL_CONNECTED event since the device is still connected. The event is fired only on changing of device state from disconnected to connected.
You have 2 options.
You can put your BroadcastReceiver with BluetoothDevice.ACTION_ACL_CONNECTED and BluetoothDevice.ACTION_ACL_DISCONNECTED filters into the Service and track the device connection state in the background. On your app startup you can ask the service to give you the current state of the device.
You can check if some of the Bluetooth profiles contains your device name in the list of connected devices.
For API 18+ you can use BluetoothManager#getConnectedDevices() for API below 18 you can use the following snippet (for each Bluetooth profile)
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
BluetoothProfile.ServiceListener mProfileListener = new BluetoothProfile.ServiceListener() {
public void onServiceConnected(int profile, BluetoothProfile proxy) {
for (BluetoothDevice device : proxy.getConnectedDevices()) {
if (device.getName().contains("DEVICE_NAME")) {
deviceConnected = true;
}
}
if (!deviceConnected) {
Toast.makeText(getActivity(), "DEVICE NOT CONNECTED", Toast.LENGTH_SHORT).show();
}
mBluetoothAdapter.closeProfileProxy(profile, proxy);
}
public void onServiceDisconnected(int profile) {
// TODO
}
};
mBluetoothAdapter.getProfileProxy(context, mProfileListener, BluetoothProfile.A2DP);

Android: Error in discovering bluetooth devices

I need some help in my Android application. I am trying to create an app that discovers bluetooth devices then compare the name to a string.
but I encountered 2 problems.
1: when I exit the app (back button) it exits then show me a crash message (after few seconds) .. I think the problem is with "mReceiver" (check "2nd problem).
2:(main problem) In the code bellow, the $"mReceiver = new BroadcastReceiver()" part has a problem. I have thrown multiple toasts every where just to check which part doesn't work, everything before this line works fine.
I'm not sure but I think the problem with not having "final" in declaring "mReciver" in the beginning --> "private BroadcastReceiver mReceiver;". However adding final causes problems.
The Code:
public class MainActivity extends Activity {
private final static int REQUEST_ENABLE_BT = 1; //It's really just a number that you provide for onActivityResult (>0)
//Temp objects for testing
private String StringMeeting = "meeting";
ProgressBar bar;
//Member fields
private BluetoothAdapter mBluetoothAdapter;
private ArrayAdapter<String> mPairedDevicesArrayAdapter;
private ArrayAdapter<String> mNewDevicesArrayAdapter;
// Create a BroadcastReceiver for ACTION_FOUND
private BroadcastReceiver mReceiver;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//declare & start progress bar
bar = (ProgressBar) findViewById(R.id.progressBar1);
bar.setVisibility(View.VISIBLE);
//------------Setup a Bluetooth (Get Adapter) ------------------
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
// Device does not support Bluetooth
Toast.makeText(getApplicationContext(), "This Device does not support Bluetooth", Toast.LENGTH_LONG).show();
}else{Toast.makeText(getApplicationContext(), "Getting the Adabter is done", Toast.LENGTH_SHORT).show();}
//------------Setup a Bluetooth (Enable Bluetooth) ------------------
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}else{Toast.makeText(getApplicationContext(), "Enable Bluetooth is done", Toast.LENGTH_SHORT).show();}
//------------Finding Devices (Discovering Devices)----------------------
// Create a BroadcastReceiver for ACTION_FOUND
Toast.makeText(getApplicationContext(), "creating the mReceiver", Toast.LENGTH_SHORT).show(); //last thing works
mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
Toast.makeText(getApplicationContext(), "accessed onReceive + will create action", Toast.LENGTH_SHORT).show();
String action = intent.getAction();
Toast.makeText(getApplicationContext(), "Waiting to discover a device", Toast.LENGTH_SHORT).show();
// When discovery finds a device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
Toast.makeText(getApplicationContext(), "enterd the if", Toast.LENGTH_SHORT).show();
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
Toast.makeText(getApplicationContext(), "Getting device names", Toast.LENGTH_SHORT).show();
Toast.makeText(getApplicationContext(), device.getName(), Toast.LENGTH_LONG).show();
Toast.makeText(getApplicationContext(), "displaying the name should be done", Toast.LENGTH_SHORT).show();
// Add the name and address to an array adapter to show in a ListView
mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}else{Toast.makeText(getApplicationContext(), "Error: BluetoothDevice.ACTION_FOUND.equals(action) = False", Toast.LENGTH_SHORT).show();}
}
};
// Register the BroadcastReceiver
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver, filter); // Don't forget to unregister during onDestroy
} //onCreate end
#Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
// Make sure we're not doing discovery anymore
if (mBluetoothAdapter != null) {
mBluetoothAdapter.cancelDiscovery();
}
// Unregister broadcast listeners
this.unregisterReceiver(mReceiver);
}
}
Thank You For Your Time.

You start an activity for result in order for the user to be prompted whether the user allows Bluetooth to be enabled or not, but you don't wait for the result and try to find devices right away.
You should implement onActivityResult call back. If the result is RESULT_OK, then you start discovering devices. Enabling bluetooth takes some time.

To discover and pair Bluetooth Devices

How to discover and pair Android Bluetooth devices using Java? Any codes for me to refer to?

the following code will discover the list of paired and the unpaired devices after that u have to implement the Client and server, which takes care of pairing the devices and sending data to the devices, for tat u can make use of the BluetoothChatSample which will give an idea to u.
private Set<BluetoothDevice> pairedDevices;
public static ArrayList<Object> BondedDeviceList;
public static ArrayList<Object> NewDeviceList;
public void makeDiscoverable()
{
discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
activity.startActivity(discoverableIntent);
}
//It will Add the paired device in the BondedDeviceList
public void queryPairedDevice(){
pairedDevices = mBluetoothAdapter.getBondedDevices();
// If there are paired devices
if(pairedDevices==null)
{
//No Bonded Devices
}else
{
if (pairedDevices.size() > 0) {
// Loop through paired devices
for (BluetoothDevice device : pairedDevices) {
BondedDeviceList.add(device);
}
BondedDeviceList.add("End");
}
}
}
//Broadcast Receiver will find the Available devices and the discovery 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.trim())) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// If it's already paired, skip it, because it's been listed already
if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
NewDeviceList.add(device);
}
// When discovery is finished, change the Activity title
} else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
if (NewDeviceList.isEmpty() == true) {
String noDevices = "No Devices";
NewDeviceList.add(noDevices);
}
System.out.println("Discovery Finished!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
NewDeviceList.add("End");
}
}
};
//This is query for the bluetooth devices
public void queryDevices(){
actionFoundFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
activity.registerReceiver(mReceiver, actionFoundFilter);
// Don't forget to unregister during onDestroy
discoveryFinishedFilter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
activity.registerReceiver(mReceiver, discoveryFinishedFilter);
// Don't forget to unregister during onDestroy
queryPairedDevice();
mBluetoothAdapter.startDiscovery();
}
//Unregister the receivers
public void unregisterReceiver() {
// Make sure we're not doing discovery anymore
if (mBluetoothAdapter != null) {
mBluetoothAdapter.cancelDiscovery();
}
// Unregister broadcast listeners
activity.unregisterReceiver(mReceiver);
}
Cheers.