Develop Reference

Update a Singleton member property from a foreground service

I have a location tracking app. I have a Foreground service that when the app goes into the background, it continues to get the location. That part works fine. If I output the location I can see the different points and correct timestamps.
While in the background I need to POST that data to an API endpoint. My GPSHeartbeat class is a singleton and it exposes a function to let me update the Singletons location property.
While in the foreground, everything works fine. When in the background, the location IS updated, but the singleton has the last location from BEFORE it went into the background.
My APICommunicator is firing in the background on its interval like it should, it just doesn't have the correct Location.
Here is the broadcast receiver that is responsible for listening to the Foreground services location change.
This works fine in the background and in the foreground. It is successfully getting the updated location.
private void onNewLocation(Location location)
{
Log.i(TAG, "onNewLocationRec'd: " + location);
mLocation = location;
// Notify anyone listening for broadcasts about the new location.
Intent intent = new Intent(ACTION_BROADCAST);
intent.putExtra(EXTRA_LOCATION, location);
LocalBroadcastManager.getInstance(getApplicationContext()).sendBroadcast(intent);
// Update notification content if running as a foreground service.
if (serviceIsRunningInForeground(this)) {
mNotificationManager.notify(NOTIFICATION_ID, getNotification());
}
}
The BroadcastReceiver is an inner class of an Activity called HomeActivity. This gets the CORRECT location from the service. If I output the log, it is the same as what the Service broadcast.
public class HomeActivity extends AppCompatActivity
{
private GPSHeartbeat mGPSHeartbeat;
private GPSReceiver myReceiver;
private LocationUpdatesService mService = null;
private boolean mBound = false;
private final ServiceConnection mServiceConnection = new ServiceConnection()
{
#Override
public void onServiceConnected(ComponentName name, IBinder service)
{
LocationUpdatesService.LocalBinder binder = (LocationUpdatesService.LocalBinder) service;
mService = binder.getService();
mBound = true;
}
#Override
public void onServiceDisconnected(ComponentName name)
{
mService = null;
mBound = false;
}
};
private void GPSBeginRequestingUpdates()
{
//Wait 5 seconds to spin up
(new Handler()).postDelayed(this::StartGPSUpdates, 5000);
}
private void StartGPSUpdates()
{
mService.requestLocationUpdates();
}
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
myReceiver = new GPSReceiver();
setContentView(R.layout.activity_home);
mGPSHeartbeat = GPSHeartbeat.instance(getApplicationContext()).setInterval(6);
}
#Override
protected void onStart()
{
super.onStart();
bindService(new Intent(getApplicationContext(), LocationUpdatesService.class), mServiceConnection, Context.BIND_AUTO_CREATE);
}
#Override
protected void onStop()
{
if (mBound) {
unbindService(mServiceConnection);
mBound = false;
}
super.onStop();
}
#Override
protected void onResume()
{
super.onResume();
LocalBroadcastManager.getInstance(getApplicationContext()).registerReceiver(myReceiver, new IntentFilter(LocationUpdatesService.ACTION_BROADCAST));
GPSBeginRequestingUpdates();
}
#Override
protected void onPause()
{
LocalBroadcastManager.getInstance(getApplicationContext()).unregisterReceiver(myReceiver);
super.onPause();
}
private class GPSReceiver extends BroadcastReceiver
{
#Override
public void onReceive(Context context, Intent intent)
{
Location location = intent.getParcelableExtra(LocationUpdatesService.EXTRA_LOCATION);
if (location != null) {
Log.i(TAG, "\nonReceived New Location: " + GPSUtils.getLocationText(location));
GPSHeartbeat.instance(context.getApplicationContext()).SetLocation(location);
}
}
}
}
The Singleton. The SetLocation() does receive the correct location. It is only during my POST request that the APICommunicator is using the GPSHeartbeat's old location. Even though it was just updated.
How do I make sure I update to the correct location?
public class GPSHeartbeat extends Service {
private static String TAG = "GPSHeartbeat";
private static volatile GPSHeartbeat _instance;
private final WeakReference<Context> mContextRef;
private Boolean isRunning = false;
private int mInterval;
private Location mLocation;
private Handler mHandler;
private ExecutorService mExecutorService = Executors.newSingleThreadExecutor();
private Future mLongRunningTaskFuture;
private Runnable mStatusChecker = new Runnable()
{
#Override
public void run()
{
try {
tick(); //this function can change value of mInterval.
}
finally {
if (isRunning()) {
// 100% guarantee that this always happens, even if your update method throws an exception
mHandler.postDelayed(mStatusChecker, mInterval);
}
}
}
};
private GPSHeartbeat(Context context)
{
mContextRef = new WeakReference<>(context.getApplicationContext());
}
public static GPSHeartbeat instance(Context context)
{
if (_instance == null) {
_instance = new GPSHeartbeat(context);
} else {
if (!context.equals(_instance.mContextRef.get())) {
_instance = null;
_instance = new GPSHeartbeat(context);
}
}
return _instance;
}
public void SetLocation(Location loc)
{
Log.i(TAG, "setLocation(): " + loc);
this.mLocation = loc;
}
public GPSHeartbeat setInterval(int interval)
{
this.mInterval = interval * 1000;
return this;
}
public void start()
{
if (isRunning()) return;
mHandler = new Handler();
mLongRunningTaskFuture = mExecutorService.submit(mStatusChecker);
mStatusChecker.run();
isRunning = true;
}
public void stop()
{
if (mHandler != null) {
mHandler.removeCallbacks(mStatusChecker);
}
if (mLongRunningTaskFuture != null) {
//kill the task:
try {
mLongRunningTaskFuture.cancel(true);
mLongRunningTaskFuture = null;
mHandler = null;
}
catch (Exception e) {
Log.e(TAG, "Unable to cancel task: " + e.getLocalizedMessage());
}
}
isRunning = false;
}
public Location currentLocation()
{
return mLocation;
}
public boolean isRunning()
{
return isRunning;
}
private void tick()
{
// Fire off the APICommuncator.Post() method
}
#Nullable
#Override
public IBinder onBind(Intent intent)
{
return null;
}
}
The APICommuncator
public class APICommuncator
{
private static String TAG = "APICommuncator";
private static volatile APICommuncator _instance;
private final WeakReference<Context> mContextRef;
private GPSHeartbeat _gpsHeartbeat;
private APICommuncator(Context context)
{
mContextRef = new WeakReference<>(context.getApplicationContext());
_gpsHeartbeat = GPSHeartbeat.instance(context.getApplicationContext());
}
public static APICommuncator i(Context context)
{
if (_instance == null) {
_instance = new APICommuncator(context);
} else {
if (!context.equals(_instance.mContextRef.get())) {
_instance = null;
_instance = new APICommuncator(context);
}
}
return _instance;
}
public void Post(){
// Do the background thing and grab
// getLocationNode() which gets the OLD location before it went to the background.
}
private JSONObject getLocationNode()
{
Location location = _gpsHeartbeat.currentLocation();
if (location == null) {
return null;
}
JSONObject node = null;
try {
node = new JSONObject();
node.put("Latitude", String.valueOf(location.getLatitude()));
node.put("Longitude", String.valueOf(location.getLongitude()));
node.put("HAccuracy", String.valueOf(location.getAccuracy()));
node.put("VAccuracy", String.valueOf(location.getAccuracy()));
node.put("Altitude", String.valueOf(location.getAltitude()));
node.put("Speed", String.valueOf(location.getSpeed() * 2.237));
node.put("Heading", String.valueOf(location.getBearing()));
node.put("Timestamp", String.valueOf((location.getTime() / 1000)));
}
catch (JSONException | NullPointerException e) {
e.printStackTrace();
}
return node;
}
}
In the Manifest:
<service
android:name=".gpsheartbeat.GPSHeartbeat"
android:exported="true"
android:permission="android.permission.BIND_JOB_SERVICE" />
<service
android:name=".gpsheartbeat.LocationUpdatesService"
android:enabled="true"
android:exported="true"
android:foregroundServiceType="location" />

Actually I don't see that you are using foreground service. Not foreground service would be killed very soon after the application goes background. Plus communication with API should be in the scope of foreground service because activity could be killed by the system.

How to pass a String from a UDP Listening Service to the MainActivity?

I have a service listening for UDP packets that is bound to my MainActivity (which is the only activity in the app). The service runs on its own thread and I can see the UDP messages as well as the parsed messages in logcat. I created a setParsedMessage() and a public getParsedMessage() in order to get the parsed string and send it to my main activity in order to change a TextView and an ImageView depending on what the parsed message is, however it does not appear to be retrieving the String for some reason. I read about this method on the Developer.Android website, however I've also seen something about using Handler to do this instead. Here is my code:
MainActivity:
public class MainActivity extends Activity {
AlertAssignments mAlertAssignments;
Button startListeningButton;
boolean started;
int counter;
boolean mBound = false;
Context context;
ListenerService mListenerService;
TextView mTextView;
TextView mBlinkView;
ImageView mImageView;
private StartListening _StartListeningTask;
String messageFromService = "";
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//start listener service
Intent listenerServiceIntent = new Intent(MainActivity.this, ListenerService.class);
this.bindService(listenerServiceIntent, mConnection, Context.BIND_AUTO_CREATE);
mImageView = (ImageView) findViewById(R.id.image_view);
mTextView = (TextView) findViewById(R.id.alert_text);
mBlinkView = (TextView) findViewById(R.id.blinking_text);
Animation mAnimation = new AlphaAnimation(0.0f, 1.0f);
mAnimation.setDuration(50);
mAnimation.setStartOffset(20);
mAnimation.setRepeatCount(Animation.INFINITE);
mAnimation.setRepeatMode(Animation.REVERSE);
mBlinkView.startAnimation(mAnimation); //animation value
mAlertAssignments = new AlertAssignments();
}
private ServiceConnection mConnection = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName className, IBinder service) {
ListenerService.LocalBinder binder = (ListenerService.LocalBinder) service;
mListenerService = binder.getService();
mBound = true;
if(mBound) {
Log.e("UDP", "Service has been bound successfully");
}
else {
Log.e("UDP", "Service has not been bound");
}
readFromService();
}
#Override
public void onServiceDisconnected(ComponentName name) {
mBound = false;
}
};
#Override
protected void onStart() {
super.onStart();
}
#Override
protected void onStop() {
super.onStop();
//unbind from service
if(mBound) {
this.unbindService(mConnection);
mBound = false;
}
}
private void readFromService() {
try {
Integer parsedMessage = Integer.valueOf(mListenerService.getParsedMessage());
mImageView.setImageResource(mAlertAssignments.alarmImages[parsedMessage]);
if(parsedMessage >= 10 && parsedMessage <= 19 && parsedMessage != 0) {
mTextView.setText(mAlertAssignments.alertTextMessages[parsedMessage]);
} else {
mBlinkView.setText(mAlertAssignments.alertTextMessages[parsedMessage]);
}
} catch(NumberFormatException e) {
e.printStackTrace();
}
}
}
I had read that using the public getter like this:
Integer parsedMessage = Integer.valueOf(mListenerService.getParsedMessage());
would allow me to access the string value of mListenerService.getParsedMessage, however I'm guessing that may only work for started services, not bound services.
AlertAssignments is a simple enumeration that uses ordinal arrays to bind images and Strings to values, so mImageView.setImageResource(mAlertAssignments.alarmImages[parsedMessage]) would set the ImageView to an image. Finally, here is the Service:
public class ListenerService extends Service{
public String the_alarm_S;
public String parsedMessage = "";
private final IBinder mBinder = new LocalBinder();
public class LocalBinder extends Binder {
ListenerService getService() {
return ListenerService.this;
}
}
#Override
public IBinder onBind(Intent intent) {
return mBinder;
}
DatagramSocket socket;
Thread UDPBroadcastThread;
void startListenForUDPBroadcast() {
UDPBroadcastThread = new Thread(new Runnable() {
public void run() {
try {
while (shouldRestartSocketListen) {
try {
socket = new DatagramSocket(12001);
socket.setReuseAddress(true);
String message = "";
byte[] recvBuf = new byte[1024];
DatagramPacket packet = new DatagramPacket(recvBuf, 1024);
Log.e("UDP", "Waiting for UDP broadcast");
try {
socket.receive(packet);
Log.e("UDP", "Received Packet");
} catch (IOException e) {
e.printStackTrace();
}
message = new String(packet.getData());
Log.e("UDP", "Got UDB broadcast message: " + message);
setParsedMessage(message);
if(socket != null) {
socket.close();
}
} catch (SocketException e) {
e.printStackTrace();
}
}
//if (!shouldListenForUDPBroadcast) throw new ThreadDeath();
} catch (Exception e) {
Log.i("UDP", "no longer listening for UDP broadcasts cause of error " + e.getMessage());
}
}
});
UDPBroadcastThread.start();
}
private Boolean shouldRestartSocketListen = true;
private void setParsedMessage(String messageContents) {
the_alarm_S = messageContents;
String parseMessage[] = the_alarm_S.split("!!!");
Log.e("UDP", "Parsed message with value " + parseMessage[1]);
parsedMessage = parseMessage[1];
}
public String getParsedMessage() {
return parsedMessage;
}
private void stopListen() {
shouldRestartSocketListen = false;
if(socket != null) {
socket.close();
}
}
#Override
public void onCreate() {
startListenForUDPBroadcast();
}
#Override
public void onDestroy() {
stopListen();
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
shouldRestartSocketListen = true;
startListenForUDPBroadcast();
Log.i("UDP", "Service started");
return START_STICKY;
}
}
Can someone give me the simplest method of getting the String from the service to the main activity, or if I already have it, where I am going wrong in using it? I would like to avoid having to rewrite my Service as an IntentService unless it's absolutely necessary to do so since this is a relatively simple object to pass to MainActivity
Thanks

You could try subscribing to the service. What I mean is pass some interface that the service calls to notify the activity about changes, here's an example I just tested:
A Subscriber interface
public interface ServiceSubscriber {
void messageCallback(String message);
}
Subscribe to the service using the Subscriber
public class TestService extends Service {
ArrayList<ServiceSubscriber> subscribers = new ArrayList<>();
private TestBinder testBinder = new TestBinder();
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
new Thread(){
#Override
public void run() {
while(true){
//this is where you are receiving UDP packets
doStuff();
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}.start();
return super.onStartCommand(intent, flags, startId);
}
#Nullable
#Override
public IBinder onBind(Intent intent) {
return testBinder;
}
private void doStuff() {
System.out.println("Service is doing stuff!");
//loop through your subscribers and notify them of your changes
//a loop here isn't very costly, if there aren't many subscribers
for (ServiceSubscriber subscriber : subscribers) {
subscriber.messageCallback("I'm doing stuff");
}
}
public class TestBinder extends Binder {
public TestService getService() {
return TestService.this;
}
}
public void subscribeToMessages(ServiceSubscriber subscriber) {
subscribers.add(subscriber);
}
public void unSubscribeToMessages(ServiceSubscriber subscriber) {
subscribers.remove(subscriber);
}
}
Now for the usual Binding Activity, where you define what you need to do with the Message Callback:
public class MainActivity extends AppCompatActivity {
private TestService testService;
private Subscriber subscriber;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
protected void onStart() {
super.onStart();
bindService(new Intent(this, TestService.class),serviceConnection, Context.BIND_AUTO_CREATE);
}
private ServiceConnection serviceConnection = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName name, IBinder service) {
testService = ((TestService.TestBinder)service).getService();
subscriber = new ServiceSubscriber() {
#Override
public void messageCallback(String message) {
//I'm just printing out the message received
//Be careful if you need to do UI stuff to use a
//Handler
System.out.println(message);
}
}
testService.subscribeToMessages(subscriber );
}
#Override
public void onServiceDisconnected(ComponentName name) {
}
};
}
Of course don't forget to unsubscribe on destroy.
Updating UI often doesn't break your app if you do it by using a handler
//activity fields
Handler handler
//in activity constructor
handler = new Handler();
//update UI by calling
handler.post(new Runnable(){
#Override
public void run(){
//update the UI here
}
EDIT: I forgot to keep a reference of the subscriber, to unsubscribe later. Changed from anonymous instance to a field.

Make below method to your sevice class:
private void sendMessage() {
Intent intent = new Intent("message");
intent.putExtra("message", your_message);
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}
And put the below code in your activity class:
#Override
public void onResume() {
super.onResume();
LocalBroadcastManager.getInstance(this)
.registerReceiver(mMessageReceiver,
new IntentFilter("message"));
}
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String yourMessage = intent.getIntExtra("message",-1);
}
};
#Override
protected void onPause() {
LocalBroadcastManager.getInstance(this)
.unregisterReceiver(mMessageReceiver);
super.onPause();
}
Note: -1 is for default value

USB Host Android Cannot Send String

I wanted my Android to communicate with an Arduino using an USB host. I've tried many references but can't seem to send any char to my Arduino. I can detect my Arduino but sending char or string to it is frustrating. Here are my codes:
MainActivity.java
public class MainActivity extends AppCompatActivity {
UsbDevice device=null;
UsbManager manager=null;
PendingIntent mPermissionIntent;
UsbInterface intf;
UsbEndpoint endpoint;
UsbDeviceConnection connection;
Button find;
Button send;
TextView hello;
UsbManager mUsbManager;
private static final String ACTION_USB_PERMISSION =
"com.android.example.USB_PERMISSION";
private byte[] bytes;
private static int TIMEOUT = 0;
private boolean forceClaim = true;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
find = (Button) findViewById(R.id.Find);
send = (Button) findViewById(R.id.Send);
hello = (TextView) findViewById(R.id.hello);
find.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
hello.setText("");
checkInfo();
}
});
send.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(device!=null) {
intf = device.getInterface(0);
endpoint = intf.getEndpoint(0);
connection = mUsbManager.openDevice(device);
hello.setText("Kirim");
String kirim = "a";
bytes = kirim.getBytes();
connection.claimInterface(intf, forceClaim);
connection.bulkTransfer(endpoint, bytes, bytes.length, 0);
}
else{
Toast.makeText(MainActivity.this,"Device ==
null",Toast.LENGTH_SHORT);
}
}
});
private void checkInfo(){
manager=(UsbManager) getSystemService(Context.USB_SERVICE);
mPermissionIntent = PendingIntent.getBroadcast(this,0,new
Intent(ACTION_USB_PERMISSION),0);
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver,filter);
HashMap<String,UsbDevice> deviceList = manager.getDeviceList();
Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
String i="";
int j=0;
while(deviceIterator.hasNext()){
device = deviceIterator.next();
manager.requestPermission(device,mPermissionIntent);
i += "\n" + "DeviceID: " + device.getDeviceId() + "\n"
+ "DeviceName: " + device.getDeviceName() + "\n"
+ "DeviceClass: " + device.getDeviceClass() + " - "
+ "DeviceSubClass: " + device.getDeviceSubclass() + "\n"
+ "VendorID: " + device.getVendorId() + "\n"
+ "ProductID: " + device.getProductId() + "\n";
j++;
}
hello.setText(i);
}
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (ACTION_USB_PERMISSION.equals(action)) {
synchronized (this) {
UsbDevice device = (UsbDevice) intent
.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(
UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
if (device != null) {
// call method to set up device communication
}
} else {
Log.d("ERROR", "permission denied for device " +
device);
}
}
}
}
};
}
I iterate using a find button and send using a send button. The iteration went just fine, but the sending didn't work. I needed to send just a character to the Arduino. My phone supports OTG and had been tested using other serial communication application to send char to Arduino and it works just fine.
Thanks in advance

using the usb serial lib in releases section at: https://github.com/felHR85/UsbSerial then import the lib and install dependencies as shown in the url. For solving the problem you can create a service class that handles usb related stuff (look at usb host android documentation for details: https://developer.android.com/guide/topics/connectivity/usb/host.html
as follows:
public class UsbService extends Service {
public static final String TAG = "UsbService";
public static final String ACTION_USB_READY = "com.felhr.connectivityservices.USB_READY";
public static final String ACTION_USB_ATTACHED = "android.hardware.usb.action.USB_DEVICE_ATTACHED";
public static final String ACTION_USB_DETACHED = "android.hardware.usb.action.USB_DEVICE_DETACHED";
public static final String ACTION_USB_NOT_SUPPORTED = "com.felhr.usbservice.USB_NOT_SUPPORTED";
public static final String ACTION_NO_USB = "com.felhr.usbservice.NO_USB";
public static final String ACTION_USB_PERMISSION_GRANTED = "com.felhr.usbservice.USB_PERMISSION_GRANTED";
public static final String ACTION_USB_PERMISSION_NOT_GRANTED = "com.felhr.usbservice.USB_PERMISSION_NOT_GRANTED";
public static final String ACTION_USB_DISCONNECTED = "com.felhr.usbservice.USB_DISCONNECTED";
public static final String ACTION_CDC_DRIVER_NOT_WORKING = "com.felhr.connectivityservices.ACTION_CDC_DRIVER_NOT_WORKING";
public static final String ACTION_USB_DEVICE_NOT_WORKING = "com.felhr.connectivityservices.ACTION_USB_DEVICE_NOT_WORKING";
public static final int MESSAGE_FROM_SERIAL_PORT = 0;
public static final int CTS_CHANGE = 1;
public static final int DSR_CHANGE = 2;
private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private static final int BAUD_RATE = 9600; // BaudRate. Change this value if you need
public static boolean SERVICE_CONNECTED = false;
private IBinder binder = new UsbBinder();
private UsbService context;
private Handler mHandler;
private UsbManager usbManager;
private UsbDevice device;
private UsbDeviceConnection connection;
private UsbSerialDevice serialPort;
private boolean serialPortConnected;
/*
* Data received from serial port will be received here. Just populate onReceivedData with your code
* In this particular example. byte stream is converted to String and send to UI thread to
* be treated there.
*/
private UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {
#Override
public void onReceivedData(byte[] arg0) {
try {
String data = new String(arg0, "UTF-8");
if (mHandler != null)
mHandler.obtainMessage(MESSAGE_FROM_SERIAL_PORT, data).sendToTarget();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
};
/*
* State changes in the CTS line will be received here
*/
private UsbSerialInterface.UsbCTSCallback ctsCallback = new UsbSerialInterface.UsbCTSCallback() {
#Override
public void onCTSChanged(boolean state) {
if(mHandler != null)
mHandler.obtainMessage(CTS_CHANGE).sendToTarget();
}
};
/*
* State changes in the DSR line will be received here
*/
private UsbSerialInterface.UsbDSRCallback dsrCallback = new UsbSerialInterface.UsbDSRCallback() {
#Override
public void onDSRChanged(boolean state) {
if(mHandler != null)
mHandler.obtainMessage(DSR_CHANGE).sendToTarget();
}
};
/*
* Different notifications from OS will be received here (USB attached, detached, permission responses...)
* About BroadcastReceiver: http://developer.android.com/reference/android/content/BroadcastReceiver.html
*/
private final BroadcastReceiver usbReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context arg0, Intent arg1) {
if (arg1.getAction().equals(ACTION_USB_PERMISSION)) {
boolean granted = arg1.getExtras().getBoolean(UsbManager.EXTRA_PERMISSION_GRANTED);
if (granted) // User accepted our USB connection. Try to open the device as a serial port
{
Intent intent = new Intent(ACTION_USB_PERMISSION_GRANTED);
arg0.sendBroadcast(intent);
connection = usbManager.openDevice(device);
new ConnectionThread().start();
} else // User not accepted our USB connection. Send an Intent to the Main Activity
{
Intent intent = new Intent(ACTION_USB_PERMISSION_NOT_GRANTED);
arg0.sendBroadcast(intent);
}
} else if (arg1.getAction().equals(ACTION_USB_ATTACHED)) {
if (!serialPortConnected)
findSerialPortDevice(); // A USB device has been attached. Try to open it as a Serial port
} else if (arg1.getAction().equals(ACTION_USB_DETACHED)) {
// Usb device was disconnected. send an intent to the Main Activity
Intent intent = new Intent(ACTION_USB_DISCONNECTED);
arg0.sendBroadcast(intent);
if (serialPortConnected) {
serialPort.close();
}
serialPortConnected = false;
}
}
};
/*
* onCreate will be executed when service is started. It configures an IntentFilter to listen for
* incoming Intents (USB ATTACHED, USB DETACHED...) and it tries to open a serial port.
*/
#Override
public void onCreate() {
this.context=this;
serialPortConnected = false;
UsbService.SERVICE_CONNECTED = true;
setFilter();
usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
findSerialPortDevice();
}
/* MUST READ about services
* http://developer.android.com/guide/components/services.html
* http://developer.android.com/guide/components/bound-services.html
*/
#Override
public IBinder onBind(Intent intent) {
return binder;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
return Service.START_NOT_STICKY;
}
#Override
public void onDestroy() {
super.onDestroy();
serialPort.close();
unregisterReceiver(usbReceiver);
UsbService.SERVICE_CONNECTED = false;
}
/*
* This function will be called from MainActivity to write data through Serial Port
*/
public void write(byte[] data) {
if (serialPort != null)
serialPort.write(data);
}
public void setHandler(Handler mHandler) {
this.mHandler = mHandler;
}
private void findSerialPortDevice() {
// This snippet will try to open the first encountered usb device connected, excluding usb root hubs
HashMap<String, UsbDevice> usbDevices = usbManager.getDeviceList();
if (!usbDevices.isEmpty()) {
// first, dump the hashmap for diagnostic purposes
for (Map.Entry<String, UsbDevice> entry : usbDevices.entrySet()) {
device = entry.getValue();
Log.d(TAG, String.format("USBDevice.HashMap (vid:pid) (%X:%X)-%b class:%X:%X name:%s",
device.getVendorId(), device.getProductId(),
UsbSerialDevice.isSupported(device),
device.getDeviceClass(), device.getDeviceSubclass(),
device.getDeviceName()));
}
for (Map.Entry<String, UsbDevice> entry : usbDevices.entrySet()) {
device = entry.getValue();
int deviceVID = device.getVendorId();
int devicePID = device.getProductId();
// if (deviceVID != 0x1d6b && (devicePID != 0x0001 && devicePID != 0x0002 && devicePID != 0x0003) && deviceVID != 0x5c6 && devicePID != 0x904c) {
if (UsbSerialDevice.isSupported(device)) {
// There is a supported device connected - request permission to access it.
requestUserPermission();
break;
} else {
connection = null;
device = null;
}
}
if (device==null) {
// There are no USB devices connected (but usb host were listed). Send an intent to MainActivity.
Intent intent = new Intent(ACTION_NO_USB);
sendBroadcast(intent);
}
} else {
Log.d(TAG, "findSerialPortDevice() usbManager returned empty device list." );
// There is no USB devices connected. Send an intent to MainActivity
Intent intent = new Intent(ACTION_NO_USB);
sendBroadcast(intent);
}
}
private void setFilter() {
IntentFilter filter = new IntentFilter();
filter.addAction(ACTION_USB_PERMISSION);
filter.addAction(ACTION_USB_DETACHED);
filter.addAction(ACTION_USB_ATTACHED);
registerReceiver(usbReceiver, filter);
}
/*
* Request user permission. The response will be received in the BroadcastReceiver
*/
private void requestUserPermission() {
Log.d(TAG, String.format("requestUserPermission(%X:%X)", device.getVendorId(), device.getProductId() ) );
PendingIntent mPendingIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
usbManager.requestPermission(device, mPendingIntent);
}
public class UsbBinder extends Binder {
public UsbService getService() {
return UsbService.this;
}
}
/*
* A simple thread to open a serial port.
* Although it should be a fast operation. moving usb operations away from UI thread is a good thing.
*/
private class ConnectionThread extends Thread {
#Override
public void run() {
serialPort = UsbSerialDevice.createUsbSerialDevice(device, connection);
if (serialPort != null) {
if (serialPort.open()) {
serialPortConnected = true;
serialPort.setBaudRate(BAUD_RATE);
serialPort.setDataBits(UsbSerialInterface.DATA_BITS_8);
serialPort.setStopBits(UsbSerialInterface.STOP_BITS_1);
serialPort.setParity(UsbSerialInterface.PARITY_NONE);
/**
* Current flow control Options:
* UsbSerialInterface.FLOW_CONTROL_OFF
* UsbSerialInterface.FLOW_CONTROL_RTS_CTS only for CP2102 and FT232
* UsbSerialInterface.FLOW_CONTROL_DSR_DTR only for CP2102 and FT232
*/
serialPort.setFlowControl(UsbSerialInterface.FLOW_CONTROL_OFF);
serialPort.read(mCallback);
serialPort.getCTS(ctsCallback);
serialPort.getDSR(dsrCallback);
//
// Some Arduinos would need some sleep because firmware wait some time to know whether a new sketch is going
// to be uploaded or not
//Thread.sleep(2000); // sleep some. YMMV with different chips.
// Everything went as expected. Send an intent to MainActivity
Intent intent = new Intent(ACTION_USB_READY);
context.sendBroadcast(intent);
} else {
// Serial port could not be opened, maybe an I/O error or if CDC driver was chosen, it does not really fit
// Send an Intent to Main Activity
if (serialPort instanceof CDCSerialDevice) {
Intent intent = new Intent(ACTION_CDC_DRIVER_NOT_WORKING);
context.sendBroadcast(intent);
} else {
Intent intent = new Intent(ACTION_USB_DEVICE_NOT_WORKING);
context.sendBroadcast(intent);
}
}
} else {
// No driver for given device, even generic CDC driver could not be loaded
Intent intent = new Intent(ACTION_USB_NOT_SUPPORTED);
context.sendBroadcast(intent);
}
}
}
}
then in your main activity put this snippets:
java
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
switch (intent.getAction()) {
case UsbService.ACTION_USB_PERMISSION_GRANTED: // USB PERMISSION GRANTED
Toast.makeText(context, "USB Ready", Toast.LENGTH_SHORT).show();
break;
case UsbService.ACTION_USB_PERMISSION_NOT_GRANTED: // USB PERMISSION NOT GRANTED
Toast.makeText(context, "USB Permission not granted", Toast.LENGTH_SHORT).show();
break;
case UsbService.ACTION_NO_USB: // NO USB CONNECTED
Toast.makeText(context, "No USB connected", Toast.LENGTH_SHORT).show();
break;
case UsbService.ACTION_USB_DISCONNECTED: // USB DISCONNECTED
Toast.makeText(context, "USB disconnected", Toast.LENGTH_SHORT).show();
break;
case UsbService.ACTION_USB_NOT_SUPPORTED: // USB NOT SUPPORTED
Toast.makeText(context, "USB device not supported", Toast.LENGTH_SHORT).show();
break;
}
}
};
private UsbService usbService;
public TextView display;
private EditText editText;
private MyHandler mHandler;
private final ServiceConnection usbConnection = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName arg0, IBinder arg1) {
usbService = ((UsbService.UsbBinder) arg1).getService();
usbService.setHandler(mHandler);
// Toast.makeText(getApplicationContext(),"dentro on service connected " + usbService, Toast.LENGTH_SHORT).show();
}
#Override
public void onServiceDisconnected(ComponentName arg0) {
usbService = null;
}
};
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.operacion);
mHandler = new MyHandler(this);
// your stuff here
#Override
public void onResume() {
super.onResume();
// Toast.makeText(getApplicationContext(),"on resume ", Toast.LENGTH_SHORT).show();
setFilters(); // Start listening notifications from UsbService
startService(UsbService.class, usbConnection, null); // Start UsbService(if it was not started before) and Bind it
// Toast.makeText(getApplicationContext(),"despues de start y weas ", Toast.LENGTH_SHORT).show();
}
#Override
public void onPause() {
super.onPause();
unregisterReceiver(mUsbReceiver);
unbindService(usbConnection);
}
private void startService(Class<?> service, ServiceConnection serviceConnection, Bundle extras) {
// Toast.makeText(getApplicationContext(),"start1", Toast.LENGTH_SHORT).show();
if (!UsbService.SERVICE_CONNECTED) {
Intent startService = new Intent(this, service);
if (extras != null && !extras.isEmpty()) {
Set<String> keys = extras.keySet();
for (String key : keys) {
String extra = extras.getString(key);
startService.putExtra(key, extra);
}
}
startService(startService);
// Toast.makeText(getApplicationContext(),"dp metodo start", Toast.LENGTH_SHORT).show();
}
Intent bindingIntent = new Intent(this, service);
bindService(bindingIntent, serviceConnection, Context.BIND_AUTO_CREATE);
}
private void setFilters() {
IntentFilter filter = new IntentFilter();
filter.addAction(UsbService.ACTION_USB_PERMISSION_GRANTED);
filter.addAction(UsbService.ACTION_NO_USB);
filter.addAction(UsbService.ACTION_USB_DISCONNECTED);
filter.addAction(UsbService.ACTION_USB_NOT_SUPPORTED);
filter.addAction(UsbService.ACTION_USB_PERMISSION_NOT_GRANTED);
registerReceiver(mUsbReceiver, filter);
}
public void getCurrentTimeUsingDate(){
String currentDateTimeString2 = DateFormat.getDateInstance().format(new Date());
TextView txtView3 = (TextView) findViewById(R.id.textView4);
txtView3.setText(""+currentDateTimeString2);
}
private static class MyHandler extends Handler {
private final WeakReference<Pag4> mActivity;
public MyHandler(Pag4 activity) {
mActivity = new WeakReference<>(activity);
}
Integer conta = 0;
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case UsbService.MESSAGE_FROM_SERIAL_PORT:
String data = (String) msg.obj;
conta++;
break;
case UsbService.CTS_CHANGE:
Toast.makeText(mActivity.get(), "CTS_CHANGE",Toast.LENGTH_LONG).show();
break;
case UsbService.DSR_CHANGE:
Toast.makeText(mActivity.get(), "DSR_CHANGE",Toast.LENGTH_LONG).show();
break;
}
}
}
}
you make a button (btn3 in the example) and then add the listener as follows:
java
bt3.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
String auxi2="1"; // put whatever you need to send here
if (!auxi2.equals("")) {
String data = auxi2;
if (usbService != null) { // if UsbService was correctly binded, Send data
usbService.write(data.getBytes());
// Toast.makeText(getApplicationContext(),"auxi2 escrito"+ auxi2, Toast.LENGTH_SHORT).show();
}
}
}
});
Hope is clear, I assume you know how to import libs, and make a button, put the permission in manifiest, dependencies. Details about this in android doc link already posted upper in my answer.

Pass a value from broadcastreceiver class to main activity in wifi direct

I want to send the value in string variable result, which is in the WiFiDirectBroadcastReceiver, to WiFiDirectActivity and I tried doing it as shown in this.
but when I ran the application it kept searching for peers. when I comment those added lines (last 3 line of WiFiDirectBroadcastReceiver) it works fine.
codes for onReceive function in WiFiDirectBroadcastReceiver and upto onResume() in WiFiDirectActivity are added.
how I can pass that value to WiFiDirectActivity? what am I missing here?
WiFiDirectBroadcastReceiver.java
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
//if (MyIntentService.ACTION_MyIntentService.equals(action))
// {
//result = intent.getStringExtra(MyIntentService.EXTRA_KEY_OUT);
result = "hello";
//}
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();
}
Log.d(WiFiDirectActivity.TAG, "P2P state changed - " + state);
} else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {
// request available peers from the wifi p2p manager. This is an
// asynchronous call and the calling activity is notified with a
// callback on PeerListListener.onPeersAvailable()
if (manager != null) {
manager.requestPeers(channel, (PeerListListener) activity.getFragmentManager()
.findFragmentById(R.id.frag_list));
}
Log.d(WiFiDirectActivity.TAG, "P2P peers changed");
} else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {
if (manager == null) {
return;
}
NetworkInfo networkInfo = (NetworkInfo) intent
.getParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);
if (networkInfo.isConnected()) {
// we are connected with the other device, request connection
// info to find group owner IP
DeviceDetailFragment fragment = (DeviceDetailFragment) activity
.getFragmentManager().findFragmentById(R.id.frag_detail);
manager.requestConnectionInfo(channel, fragment);
//fragment.peerCountInfo=result;
//fragment.peerCt = peerCountFromDlist;
//fragment.peerNm = peerNameFromDlist;
} else {
// It's a disconnect
activity.resetData();
}
} else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
DeviceListFragment fragment = (DeviceListFragment) activity.getFragmentManager()
.findFragmentById(R.id.frag_list);
fragment.updateThisDevice((WifiP2pDevice) intent.getParcelableExtra(
WifiP2pManager.EXTRA_WIFI_P2P_DEVICE));
//peerCountFromDlist = fragment.peerTot;
//peerNameFromDlist = fragment.deviceid;
}
intent.putExtra("message",result);
intent.setClass(context, WiFiDirectActivity.class);
context.startActivity(intent);
}
WiFiDirectActivity.java
public class WiFiDirectActivity extends Activity implements ChannelListener, DeviceActionListener {
public static final String TAG = "wifidirectdemo";
private WifiP2pManager manager;
private boolean isWifiP2pEnabled = false;
private boolean retryChannel = false;
private final IntentFilter intentFilter = new IntentFilter();
private Channel channel;
private BroadcastReceiver receiver = null;
private String resultString;
private int peerCount;
/**
* #param isWifiP2pEnabled the isWifiP2pEnabled to set
*/
public void setIsWifiP2pEnabled(boolean isWifiP2pEnabled) {
this.isWifiP2pEnabled = isWifiP2pEnabled;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// add necessary intent values to be matched.
intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
intentFilter.addAction(MyIntentService.ACTION_MyIntentService);
manager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
channel = manager.initialize(this, getMainLooper(), null);
}
/** register the BroadcastReceiver with the intent values to be matched */
#Override
public void onResume() {
super.onResume();
receiver = new WiFiDirectBroadcastReceiver(manager, channel, this);
registerReceiver(receiver, intentFilter);
Bundle extras = getIntent().getExtras();
if (extras != null) {
resultString = extras.getString("message");
}
}

I found this easy way to send some data to Main Activity from BroadcastReceiver thanks to Mike M. (same way setIsWifiP2pEnabled(boolean isWifiP2pEnabled) method works)
sending "message" and retrieving it to str variable ;
create a public method in the MainActivity :
public void setResult(String result){
str = result;
}
Then call it in the BroadcastReceiver :
activity.setResult("message");

How to pass a handler from activity to service

How to pass handler from an activity to service? I am trying to update the activity UI on the state of Bluetooth connection by using Handler as shown below from service class.
mHandler.obtainMessage(MenuActivity.MESSAGE_STATE_CHANGE, state, -1).sendToTarget();
In the activity, I implemented this:
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_STATE_CHANGE:
if (true)
Log.i(TAG, "MESSAGE_STATE_CHANGE: " + msg.arg1);
switch(msg.arg1){
case BluetoothService.STATE_CONNECTED:
showToast("Connected to " + mConnectedDeviceName, Toast.LENGTH_SHORT);
break;
I tried to use a constructor to pass the handler from the activity to service like this:
public BluetoothService(Handler handler, BluetoothAdapter mBluetoothAdapter) {
mAdapter = mBluetoothAdapter;
mState = STATE_NONE;
mHandler = handler;
}
But there was an error which shows Unable to instantiate service and found that the service needs to have a public no-args constructor. But after removing the constructor, the handler did not get passed into the service.
How to solve this problem?

You have to bind to the service from activity and establish a ServiceConnection and then get the instance of service and set your handler.
Here is the activity and service class which i use for one of my media player application.....
public class MainActivity extends Activity
{
private CustomService mService = null;
private boolean mIsBound;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
startService(new Intent(this.getBaseContext(), CustomService.class));
doBindService();
}
private ServiceConnection mConnection = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder)
{
mService = ((CustomService.LocalBinder)iBinder).getInstance();
mService.setHandler(yourHandler);
}
#Override
public void onServiceDisconnected(ComponentName componentName)
{
mService = null;
}
};
private void doBindService()
{
// Establish a connection with the service. We use an explicit
// class name because we want a specific service implementation that
// we know will be running in our own process (and thus won't be
// supporting component replacement by other applications).
bindService(new Intent(this,
CustomService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
}
private void doUnbindService()
{
if (mIsBound)
{
// Detach our existing connection.
unbindService(mConnection);
mIsBound = false;
}
}
#Override
protected void onDestroy()
{
super.onDestroy();
doUnbindService();
}
}
CustomService Code ....
public class CustomService extends Service
{
private final IBinder mIBinder = new LocalBinder();
private Handler mHandler = null;
#Override
public void onCreate()
{
super.onCreate();
}
#Override
public int onStartCommand(Intent intent, int flag, int startId)
{
return START_STICKY;
}
#Override
public void onDestroy()
{
if(mHandler != null)
{
mHandler = null;
}
}
#Override
public IBinder onBind(Intent intent)
{
return mIBinder;
}
public class LocalBinder extends Binder
{
public CustomService getInstance()
{
return CustomService.this;
}
}
public void setHandler(Handler handler)
{
mHandler = handler;
}
}