I have written a service in android.I want to repeatedly perform a task using service. That is the service shouldn't die and should perform the task repeatedly. However,the service performs the task just once and then gets killed.How to perform the task repeatedly in background.
My current code is->
public class SyncService extends Service {
private Looper mServiceLooper;
private ServiceHandler mServiceHandler;
#Override
public void onCreate() {
// Start up the thread running the service. Note that we create a
// separate thread because the service normally runs in the process's
// main thread, which we don't want to block. We also make it
// background priority so CPU-intensive work will not disrupt our UI.
HandlerThread thread = new HandlerThread("ServiceStartArguments", Process.THREAD_PRIORITY_BACKGROUND);
thread.start();
// Get the HandlerThread's Looper and use it for our Handler
mServiceLooper = thread.getLooper();
mServiceHandler = new ServiceHandler(mServiceLooper);
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Toast.makeText(SyncService.this, "servicestarting", Toast.LENGTH_SHORT).show();
Message msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
mServiceHandler.sendMessage(msg);
// If we get killed, after returning from here, restart
return START_STICKY;
}
#Override
public IBinder onBind(Intent intent) {
// We don't provide binding, so return null
return null;
}
#Override
public void onDestroy() {
Toast.makeText(SyncService.this, "service done", Toast.LENGTH_SHORT).show();
}
// Handler that receives messages from the thread
private final class ServiceHandler extends Handler {
public ServiceHandler(Looper looper) {
super(looper);
}
#Override
public void handleMessage(Message msg) {
Toast.makeText(SyncService.this, "repeatedly perform some task", Toast.LENGTH_SHORT).show();
//constantly perform task here
}
}
}
How to repeatedly perform some task using service?
Well you only send one message to the Handler. So that message will be processed once. You could have the Handler pass the same message back again, but with no delay that isn't a good idea- you'll deadlock the main thread. The best way to do something repeatedly would be to spin off a Thread and do it in the Thread, with the Thread's Runnable looping forever.
Related
Getting ANR executing a blocking/heavy call for Intent.ACTION_SCREEN_ON. Below is the code
private static BroadcastReceiver mScreenOnReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (action.equals(Intent.ACTION_SCREEN_ON)) {
// Blocking operation
}
}
}
To avoid ANR, I am planning to move the Blocking operation inside worker thread. Will the below code help in avoiding the ANR?
private static BroadcastReceiver mScreenOnReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (action.equals(Intent.ACTION_SCREEN_ON)) {
new Handler().post(new Runnable() {
#Override
public void run() {
//Blocking operation
}
});
}
}
}
No. BroadcastReceivers are short-lived. There is no guarantee that the OS process hosting your BroadcastReceiver will live long enough to execute this code. Not only that, but you would be running this code on the Main (UI) thread, which you cannot block (your Runnable will not run in a "worker thread", it will run in the Main (UI) thread).
Your BroadcastReceiver should start a Service, which can run a background (worker) thread which can perform your blocking operation. Or you may be able to use JobScheduler to schedule this operation (if it is suitable for your purpose).
I was reading about services in Android and especially i came down to this
While an app is in the foreground, it can create and run both
foreground and background services freely. When an app goes into the
background, it has a window of several minutes in which it is still
allowed to create and use services. At the end of that window, the app
is considered to be idle. At this time, the system stops the app's
background services, just as if the app had called the services'
Service.stopSelf() methods.
In the code below, when the app goes to background after one minute or so the services gets destroy but the thread still executes.
So what is the point of killing a service? The process/thread is still being execute.
Why killing a service in the first place? What if i want to execute a download process and NOT wanted to be a foreground process?
public class HelloService extends Service {
private Looper mServiceLooper;
private ServiceHandler mServiceHandler;
// Handler that receives messages from the thread
private final class ServiceHandler extends Handler {
public ServiceHandler(Looper looper) {
super(looper);
}
#Override
public void handleMessage(Message msg) {
// Normally we would do some work here, like download a file.
// For our sample, we just sleep for 5 seconds.
Log.d("sssssssss",msg.toString()+"sssssssssss");
while(true){
Log.d("sssssssss","sssssssssss");
}
// Stop the service using the startId, so that we don't stop
// the service in the middle of handling another job
//stopSelf(msg.arg1);
}
}
#Override
public void onCreate() {
// Start up the thread running the service. Note that we create a
// separate thread because the service normally runs in the process's
// main thread, which we don't want to block. We also make it
// background priority so CPU-intensive work doesn't disrupt our UI.
HandlerThread thread = new HandlerThread("ServiceStartArguments",
Process.THREAD_PRIORITY_BACKGROUND);
thread.start();
// Get the HandlerThread's Looper and use it for our Handler
mServiceLooper = thread.getLooper();
mServiceHandler = new ServiceHandler(mServiceLooper);
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Toast.makeText(this, "service starting", Toast.LENGTH_SHORT).show();
// For each start request, send a message to start a job and deliver the
// start ID so we know which request we're stopping when we finish the job
Message msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
mServiceHandler.sendMessage(msg);
// If we get killed, after returning from here, restart
return START_STICKY;
}
#Override
public void onDestroy() {
Toast.makeText(this, "service done", Toast.LENGTH_SHORT).show();
}
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
}
System is letting You perform a clean finish of the Service by triggering its destroy method. Your thread won't run forever, I think 30 min is hard limit before app process is killed.
This is new policy since android O to preserve battery life and improve performance. A lot of developers performed heavy operations in background (sockets open non-stop, periodic sensor readings etc.) and without foreground notification users were unaware of why their devices were sluggish and had poor battery uptime.
Read more on Background Execution Limits doc.
I want to show local notification in an Android app that i am working. notification are based on network transaction completed in background.
I have tried service, intent service, jobservice etc but nothing is working when the app is closed.please share some working code for the reference.....
//Here is my service----
public class JobSyncFAQ extends Service {
private Message msg;
private Looper mServiceLooper;
private ServiceHandler mServiceHandler;
public JobSyncFAQ() {
}
private final class ServiceHandler extends Handler {
public ServiceHandler(Looper looper) {
super(looper);
}
#Override
public void handleMessage(Message msg) {
// here is my stuff
stopSelf(msg.arg1);
}
}
public void onCreate() {
super.onCreate();
HandlerThread thread = new HandlerThread("JobSyncFAQ", Process.THREAD_PRIORITY_BACKGROUND);
thread.start();
mServiceLooper = thread.getLooper();
mServiceHandler = new ServiceHandler(mServiceLooper);
}
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
mServiceHandler.sendMessage(msg);
return START_STICKY;
}
#Override
public void onDestroy() {
super.onDestroy();
mServiceHandler.removeCallbacks(mServiceLooper.getThread());
mServiceLooper.quit();
Intent intent = new Intent(getApplicationContext(),JobSyncFAQ.class);
sendBroadcast(intent);
}
//and in my receiver
public void onReceive(Context context, Intent intent) {
context.startService(new Intent(context, JobSyncFAQ.class));
}
please note - i am facing this issue only for N+ version
When you "close" your app (i. e. you swipe it away on the recent apps screen), you don't actually close the app, you only close the underlying activity. In most cases, this corresponds to the app being closed, but if you have a background service running, the service is not terminated. This is for a good reason: YOu still want to receive WhatsApp messages, even when WhatsApp is closed. Hence, WhatsApp starts a background service to check for new messages, even when the app is closed.
For that reason, you need to notify your background service about the fact that it should cancel its task.
I developed a media application that uses a MediaBrowserService which is connected to a MediaController. Therefore, I can do the following in my activities onDestroyMethod:
MediaControllerCompat mediaControllerCompat = MediaControllerCompat.getMediaController(getActivity());
if (mediaControllerCompat != null)
mediaControllerCompat.getTransportControls().stop();
This tells the MediaBrowserService to stop and quit.
Edit: Since you use a generic service, you need to call stopService:
stopService(new Intent(MyActivity.this, JobSyncFAQ.class));
I am used to developing standalone applications, ones that you click on, it runs, and when you are done, you exit.
I am now interested in tackling a new type (not sure if that's the right word) of app, and was wondering how I should go about it. I am not sure what to research, and would appreciate your advice to help me get the ball rolling. I'll give you an idea about what I have in mind.
My app would need to perform a special action in the dialer. When the user dials a number and is in the middle of a call, I would like the user to be able to press the Menu key, and find an option to scroll through all their contacts (either the stock app, or my own list which I grab from the contacts stored in the phone), and select one. Upon selection, that contact's number is pasted into the dialer (keep in mind, in the middle of a call).
I certainly don't expect an answer telling me how to do this exactly, I just need some guidance as I have never written an app of this nature before. On top of that, is it even possible to do what I want to do?
Thank you.
You need to go through Android Service or IntentService. A Service is an application component that can perform long-running operations in the background and does not provide a user interface(UI).
The following example is taken from android blog which is an implementation of the Service class
public class HelloService extends Service {
private Looper mServiceLooper;
private ServiceHandler mServiceHandler;
// Handler that receives messages from the thread
private final class ServiceHandler extends Handler {
public ServiceHandler(Looper looper) {
super(looper);
}
#Override
public void handleMessage(Message msg) {
// Normally we would do some work here, like download a file.
// For our sample, we just sleep for 5 seconds.
long endTime = System.currentTimeMillis() + 5*1000;
while (System.currentTimeMillis() < endTime) {
synchronized (this) {
try {
wait(endTime - System.currentTimeMillis());
} catch (Exception e) {
}
}
}
// Stop the service using the startId, so that we don't stop
// the service in the middle of handling another job
stopSelf(msg.arg1);
}
}
#Override
public void onCreate() {
// Start up the thread running the service. Note that we create a
// separate thread because the service normally runs in the process's
// main thread, which we don't want to block. We also make it
// background priority so CPU-intensive work will not disrupt our UI.
HandlerThread thread = new HandlerThread("ServiceStartArguments",
Process.THREAD_PRIORITY_BACKGROUND);
thread.start();
// Get the HandlerThread's Looper and use it for our Handler
mServiceLooper = thread.getLooper();
mServiceHandler = new ServiceHandler(mServiceLooper);
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Toast.makeText(this, "service starting", Toast.LENGTH_SHORT).show();
// For each start request, send a message to start a job and deliver the
// start ID so we know which request we're stopping when we finish the job
Message msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
mServiceHandler.sendMessage(msg);
// If we get killed, after returning from here, restart
return START_STICKY;
}
#Override
public IBinder onBind(Intent intent) {
// We don't provide binding, so return null
return null;
}
#Override
public void onDestroy() {
Toast.makeText(this, "service done", Toast.LENGTH_SHORT).show();
}
}
On the other hand, The same thing can be achieved using IntentService, which is a base class for Services that handle asynchronous requests on demand.
public class HelloIntentService extends IntentService {
/**
* A constructor is required, and must call the super IntentService(String)
* constructor with a name for the worker thread.
*/
public HelloIntentService() {
super("HelloIntentService");
}
/**
* The IntentService calls this method from the default worker thread with
* the intent that started the service. When this method returns, IntentService
* stops the service, as appropriate.
*/
#Override
protected void onHandleIntent(Intent intent) {
// Normally we would do some work here, like download a file.
// For our sample, we just sleep for 5 seconds.
long endTime = System.currentTimeMillis() + 5*1000;
while (System.currentTimeMillis() < endTime) {
synchronized (this) {
try {
wait(endTime - System.currentTimeMillis());
} catch (Exception e) {
}
}
}
}
}
You can also go through SO post https://stackoverflow.com/a/4353653/432903
If your app isn't mainly written in javascript/webview/phonegap, then all you have to do is look at the Service class. That class and the linked documents tell you everything you need to know.
maybe you can use an IntentFilter so you can get a system notify when the user uses a dialer.
and you should learn the Service component which can work in background in android.
Following Googles examples for using a Service, I created a couple of threads like this. I can't use IntentService, because I'm doing something that involves waiting for callbacks.
However, I don't know how to terminate a Thread started in this manner. As I understand it, Threads automatically terminate when the run() method returns. However, this kind of thread doesn't have a run method. My Threads are leaking--they stay alive after stopSelf().
#Override
public void onCreate() {
HandlerThread thread = new HandlerThread("ServiceStartArguments",
android.os.Process.THREAD_PRIORITY_BACKGROUND);
thread.start();
HandlerThread thread2 = new HandlerThread("CallbackHandling",
android.os.Process.THREAD_PRIORITY_BACKGROUND);
thread2.start();
mServiceLooper = thread.getLooper();
mCallbackLooper = thread2.getLooper();
mServiceHandler = new MyHandler(mServiceLooper);
mCallbackHandler = new Handler(mCallbackLooper);
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Toast.makeText(this, "service starting", Toast.LENGTH_SHORT).show();
// For each start request, send a message to start a job and deliver the
// start ID so we know which request we're stopping when we finish the job
Message msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
mServiceHandler.sendMessage(msg);
mMainThreadHandler=new Handler();
// If we get killed, after returning from here, restart
return START_STICKY;
}
private final class MyHandler extends Handler {
public MyHandler(Looper looper) {
super(looper);
}
#Override
public void handleMessage(Message msg) {
cycle();
// Stop the service using the startId, so that we don't stop
// the service in the middle of handling another job
stopSelf(msg.arg1);
}
}
protected void cycle() {
...
mCallbackHandler.post(new Runnable(){
public void run(){
goAskForSomeCallbacks();
}
});
try {
Thread.sleep(GIVE_UP_TIME);
} catch (InterruptedException e){
//The callback will interrupt this thread to stop it from waiting
Log.d(TAG,"Got early callback, stop waiting.");
}
Thread.interrupted(); //clear the interrupt
doStuff();
}
Try calling the quit method on the corresponding Loopers.
You can call quit method on your handler threads.
e.g.
thread.quit();
thread2.quit();
You can also use the following recommended approach:
but be careful before using it because it cancels all pending jobs
handler.quitSafely();
Force closing the app does it but otherwise they just keep going on their own.