I am implementing Bluetooth support via implementing a task which searches for devices in the background and provides a list when the search is complete. However, this list occasionally contains a No devices found entry (added only when ACTION_DISCOVERY_FINISHED is received with no devices already in the list) before listing other devices!
private BroadcastReceiver mBlueToothInfoDiscoveryListener = new BroadcastReceiver() {
/**
* This is an overridden function called by the framework whenever there
* is some broadcast message for Bluetooth info discovery listener
*/
#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
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) {
mNewBtDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}
} else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
// When discovery is finished, change the Activity title
setProgressBarIndeterminateVisibility(false);
setTitle("device list");
if (mNewBtDevicesArrayAdapter.getCount() == 0) {
String noDevices = "No devices found";
mNewBtDevicesArrayAdapter.add(noDevices);
}
}
}
};
I don't expect ACTION_DISCOVERY_FINISHED to ever come before a ACTION_FOUND event, so why would the No devices found string be added to the list before a device is located?
Simply because the discovery task has a timeout to prevent endless searched. So, in case there is no available device around, you'll get your "No Devices found"...
Related
btAdapter.isDiscovering(),btAdapter.startDiscovery(); btAdapter.cancelDiscovery(); device.getName();
4four erros
Call requires permission which may be rejected by user: code should explicitly check to see if permission is available (with checkPermission) or explicitly handle a potential SecurityException
Please solve this problem
public void onClickButtonSearch(View view){
// Check if the device is already discovering
if(btAdapter.*isDiscovering()*){
*btAdapter.cancelDiscovery()*;
} else {
if (btAdapter.isEnabled()) {
*btAdapter.startDiscovery();*
btArrayAdapter.clear();
if (deviceAddressArray != null && !deviceAddressArray.isEmpty()) {
deviceAddressArray.clear();
}
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(receiver, filter);
} else {
Toast.makeText(getApplicationContext(), "bluetooth not on", Toast.LENGTH_SHORT).show();
}
}
}
// Create a BroadcastReceiver for ACTION_FOUND.
private final BroadcastReceiver receiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
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
btArrayAdapter.add(deviceName);
deviceAddressArray.add(deviceHardwareAddress);
btArrayAdapter.notifyDataSetChanged();
}
}
};
protected void onDestroy() {
super.onDestroy();
// Don't forget to unregister the ACTION_FOUND receiver.
unregisterReceiver(receiver);
}
For apps targeting Android 11 or lower, calling BluetoothAdapter#startDiscovery() requires the Manifest.permission#BLUETOOTH_ADMIN permission which can be gained with a simple manifest tag.
For apps targeting API Level 31 or higher, this requires the Manifest.permission#BLUETOOTH_SCAN permission.
In addition, this requires either the Manifest.permission#ACCESS_FINE_LOCATION permission or a strong assertion that you will never derive the physical location of the device.
A permission can be gained with the following code:
getActivity().requestPermissions(new String[]{ Manifest.permission.ACCESS_FINE_LOCATION},
YOUR_REQUEST_LOCATION_PERMISSION_CODE);
For more infos: https://developer.android.com/reference/android/bluetooth/BluetoothAdapter#startDiscovery()
Problem: I am being notified when a bluetooth device is pairing, or becomes paired. However, I do not know how to get notified when a device is being unpaired. How could I get my app to recognize when it has become unpaired with my device?
Example: Let's say that I pair my surface tablet and my android phone through code. My broadcast receiver will register the ACTION_BOND_STATE_CHANGED intent and allow me to process it however I want. Now, if I want to unpair my surface tablet, I do not get notified on my phone that the device has become unpaired. If I check, device.getBondState() for the device after it has been unpaired, it equals BOND_BONDED (which it clearly isnt) I can get it to recognize it is unpaired again after I try to connect to the unpaired device, then the app crashes and then when I turn the app on again, only then does it recognize it as unpaired.
Scenario: I have a BroadcastReceiver registered to listen for intents caused by a BluetoothDevice
getActivity().registerReceiver(broadcastReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
getActivity().registerReceiver(broadcastReceiver, new IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED));
getActivity().registerReceiver(broadcastReceiver, new IntentFilter(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED));
getActivity().registerReceiver(broadcastReceiver, new IntentFilter(BluetoothDevice.ACTION_ACL_DISCONNECTED));
I process these Actions with this BroadcastReciever:
final BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
System.out.println("ACTION: "+ action);
// When discovery finds a device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
list();
// Get the BluetoothDevice object from the intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
System.out.println("FOUND: " + device.getName() + " STATE: " + device.getBondState());
mapInput(device);
// Add the name and the mac address of the object to the array adapter
BTSimpleAdapter.notifyDataSetChanged();
} else if (BluetoothDevice.ACTION_BOND_STATE_CHANGED.equals(action)) {
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
System.out.println("UPDATE Name " + device.getName() + " Value " + device.getAddress() + " Bond state " + device.getBondState());
for (Map<String, String> entry : data) {
if (entry.get("Name").equals(device.getName()) && entry.get("Value").equals(device.getAddress())) {
if (device.getBondState() == BluetoothDevice.BOND_NONE) {
entry.put("Paired", "Unpaired");
} else if (device.getBondState() == BluetoothDevice.BOND_BONDING) {
entry.put("Paired", "Pairing");
} else {
entry.put("Paired", "Paired");
}
BTSimpleAdapter.notifyDataSetChanged();
}
}
}
}
};
I'm using code from the Android developer website to detect Bluetooth devices in range, and adding them to an ArrayAdapter. Problem is, each device gets added to the ArrayAdapter 5-6 times. Right now, I'm just using the code from here: http://developer.android.com/guide/topics/connectivity/bluetooth.html#DiscoveringDevices
Here's what I have:
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
mBluetoothAdapter.startDiscovery();
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());
}
}
};
Any idea what's causing this? And what can I do to get a device to be added only once to the ArrayAdapter, instead of 5 times?
I'm not sure if its a bug or what but I've also experienced this on some of my devices. To solve this, add found devices in a List only once with some checks. See below:
private List<BluetoothDevice> tmpBtChecker = new ArrayList<BluetoothDevice>();
final BroadcastReceiver mReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery starts
if(BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)){
//clearing any existing list data
tmpBtChecker.clear();
}
// 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
if(!tmpBtChecker.contains(device)){
tmpBtChecker.add(device);
mArrayAdapter.add(device.getName()+"\n"+device.getAddress());
}
}
}
};
I am developing a bluetooth app for android on the 2.2 platform. I have two instances of mArrayAdapter in my code, and both of them cannot be resolved. My code is almost exactly the same as the code on the Android dev site, because I used it as an example. I have tried defining the variables locally, but then I get an error on .add after mArrayAdapter. I have found articles that have similar issues, but none of their answers have worked for me. I think that I have to define it somewhere, but there is not any notation about that I have found online. I will paste some of by code below. Thanks.
//Find the paired Devices
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
//If there are paired devices
if (pairedDevices.size() > 0) {
// Loop through paired devices
for (BluetoothDevice device : pairedDevices) {
// Add the name and address to an array adapter to show in a ListView
//---------------------> ERROR BELOW <------------------------
mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}
}
// Discovering Bluetooth Devices.
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);
//Log.v("bluetooth Tesing",device.getName() + "\n" + device.getAddress());
// Add the name and address to an array adapter to show in ListView.
//---------------------> ERROR BELOW <------------------------
mArrayAdapter.add(device.getName() +"\n" + device.getAddress());
}
}
};
In the Sample Bluetooth Chat, DeviceListActivity which you are using as a templete, you will see that the two ArrayAdapter adapters are both declared as member variables in the class (hence the 'm' prefix) near the top of the class. They are both instantiated with
m?????ArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name);
in the onCreate. You need to do something analagous for your one adapter before trying to add an item to it.
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.