I have an activity, which I used as a custom loading dialog (the dialog is pretty complex and has custom UI, which fits the customer colors schemes, etc.).
The loading dialog is created and shown from class, which is not derived from Activity class (this I am mentioning becuase the startActivityForResult() cannot be called):
private void showLoadingDialog()
{
Intent intent = new Intent( this, ActivityDialogLoading.class );
intent.addFlags( Intent.FLAG_ACTIVITY_NEW_TASK );
startActivity( intent );
isLoadingDialogShown = true;
}
The dialog is shown when long running asynchronous tasks are performed by the application on background.
Now when the background tasks if finished I want to close the loading dialog (The loading dialog has also the Cancel button, so client can interrupt the task, but this is other story).
I did not found a way to get the reference to the instance of the running ActivityDialogLoading class to call the finish() method...
The way I am using is a bit complicated - I override BroadcastReceiver so it takes the reference to the ActivityDialogLoading in its constructor. In OnResume() method of the ActivityDialogLoading I register as a receiver for broadcasted intent.
When I need to close the loading dialog i broadcast the intent... Is there a better way?
Saying the same with other words: What is the best way to close an activity when the close action is caused by some background event in application engine?
Related
I have been scouting around for a while, but cannot locate any information for calling final() using started services... or rather, when not using bound services. There is tons of info for bound services, but I already have two pretty large "started services" without binding, so I didn't want to modify the existing services more than absolutely necessary.
My app works by reading bluetooth data every 10 seconds, and depending on the data read, the Service will change to a new activity. However, I cannot call final() from my services, so I fear that I might be endlessly stacking activities while the application/services are running.
To change activities, I had to add Intent.FLAG_ACTIVITY_NEW_TASK. Considering the below image/definition from the developer's page, this flag looks like it might already handle my stacking issue? I do NOT allow for users to use the back button on their phones as everything is handled via confirm/cancel buttons and the services. My app MUST be this way for a few reasons. Thus, keeping the stack order isn't important to my application.
Key Points -
I want to ensure i'm not stacking up activities endlessly when starting new activities
Flagging "new task" when starting activities via my services
Stack order is not important to my app
Below is a very small cut of my code with comments to explain what i'm trying to do. Please make sure to look to the onDestroy() method of this service.
public class AlertService extends Service {
final class Threader implements Runnable{
// Scans bluetooth advertisement packets every 10 seconds
// Thread Runs until interrupted
// Stops service via service ID
stopSelf(this.serviceID);
}
#Override
public void onCreate(){
super.onCreate();
}
// Runs a thread until alert is found.
// Alert calls thread.interrupt()
#Override
public int onStartCommand(Intent intent, int flags, int startID){
enableBluetooth();
// Start Thread
thread = new Thread(new Threader(startID));
thread.start();
return START_STICKY;
}
#Override
public void onDestroy(){
thread.interrupt();
Intent alertActivity = new Intent(this, AlertActivity.class)
alertActivity.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(alertActivity);
}
// Unused Method - We will not be binding
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
}
EDIT via recommendation to use android:taskAffinity -
Using android:taskAffinity won't help me in this situation. By default, all activities in an application have the same affinity. When I create a new task by setting Intent.FLAG_ACTIVITY_NEW_TASK in the intent flags, the new activity will STILL be started in the same task if the activity has the same taskAffinity of the root activity in the task. Since I am just using the default affinity, everything should have the normal stack flow. I just cannot call finish(), which means that I am stacking up tons of activities.
To answer my own question, each new activity called via Intent.FLAG_ACTIVITY_NEW_TASK, was creating a new instance of each activity and putting it on the stack. This is true. However, each activity is NOT making a new Task, which was one of my fears as well.
When I create a new task by setting Intent.FLAG_ACTIVITY_NEW_TASK in the intent flags, the new activity will STILL be started in the same task (not in a new task) if the new activity has the same taskAffinity of the root activity in the task. Since I am just using the default affinity, every activity I create is being put into the same task. This means that nothing is acting any differently than the normal flow of creating activities and such.
Though, since I have disable the back button for my application, these activities created by flagging a new task are not finished, destroyed, or removed from the stack. To solve this, I will use FLAG_ACTIVITY_CLEAR_TOP, which finds a running instance of an activity in the stack (if there is one) and closes all of the activities above it.
Since my application always starts with the home screen, then ends with the home screen, flagging "clear top" will always close all activities above my home screen. So, upon return to the home screen, the only item on the stack will be the home screen.
I will have to test this, but it seems that I will not call finish() from my home activity to achieve this result - Otherwise, upon returning to the home activity, not all of the stack will be cleared.
My activity starts a service which runs a CountDownTimer. The timer sends broadcasts back to the activity as it counts down. The activity processes the broadcasts in the onReceive method of a BroadcastReceiver. All of this works fine.
My problem comes when the following events happen in this order:
App is stopped (via onPause())
Timer finishes
App is resumed (via onResume())
When the app is resumed the service is no longer sending broadcasts, so the activity does not know how much time is left on the timer or if it's finished. This prevents the activity from updating the UI.
I've tried a dozen ways of dealing with this, and read through many Stack Overflow questions and answers, but I've yet to find a solution. I would think that there's a way to pick up a broadcast that was sent while the activity was not active, but I've yet to find a way.
For the record, here is my relevant Activity and Service code:
activity.java
// Start service
timerIntent.putExtra("totalLength", totalLength);
this.startService(timerIntent);
// ...
// BroadcastReceiver
private BroadcastReceiver br = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getExtras() != null && inSession) {
session.setRemaining(intent.getExtras().getLong("millisUntilFinished"));
updateProgress();
}
}
};
// ...
// onResume
#Override
public void onResume() {
super.onResume();
registerReceiver(br, new IntentFilter(TimerService.COUNTDOWN_TS));
}
service.java
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
long length = intent.getExtras().getLong("totalLength");
countDownTimer = new CountDownTimer(length, 1000) {
#Override
public void onTick(long millisUntilFinished) {
timerServiceIntent.putExtra("millisUntilFinished", millisUntilFinished);
sendBroadcast(timerServiceIntent);
}
#Override
public void onFinish() {
}
};
countDownTimer.start();
return super.onStartCommand(intent, flags, startId);
}
What's the best way to process the broadcasts that the service sent while the activity was stopped?
Use the BroadcastReceiver to store the last request (SharedPreferences perhaps) it received and check it when the Activity starts.
Alternatively, instead of processing a countdown using broadcasts, just store the time that the countdown would end. The Activity can then handle the countdown all by itself as it knows when it should end. Using a service and broadcasts seem to be a little over-engineered for such a simple task.
Update:
From the way you have described your task, I see you needing to handle 2 scenarios. This is how I would likely do it.
Assuming that "XYZ" is the service\intent\whatever starting the countdown and "ABC" is the Activity displaying the progress. (ABC and XYZ could be the same activity if that is what you wanted)
Requirements:
When the countdown starts, I would make XYZ store the time that the countdown should end in SharedPreferences.
ABC is already running when the countdown starts. As Commonsware said, the Eventbus model is excellent for handling this scenario so long as XYZ and ABC are running in the same process. Just fire an event to read the preference value and count down to the specified time. If the user closes ABC and reopens it, Scenario 2 will kick in.
ABC is not running. Check in OnResume whether the countdown time has elapsed. If not, set up ABC to display the countdown again. If there is no countdown active, do something else.
If you also need to do something when the countdown has elapsed regardless of whether you have a UI active, then again Commonsware's suggestion of AlarmManager is perfect.
Let's pretend for a moment that using a Service with a CountDownTimer to track some passage of time for the purposes of updating an Activity actually is a good idea. It's not out of the question, assuming that the Service is actually doing something for real and this timing thing is some by-product.
An activity does not receive broadcasts while stopped, mostly for performance/battery reasons. Instead, the activity needs to pull in the current status when it starts, then use events (e.g., your current broadcasts) to be informed of changes in the data while it is started.
This would be simplified by using something like greenrobot's EventBus and their sticky events, as the activity would automatically get the last event when it subscribes to get events. Using greenrobot's EventBus for this purpose would also reduce the security and performance issues that you are introducing by your use of system broadcasts to talk between two Java classes in the same process.
Also, please stick with lifecycle pairs. onResume() is not the counterpart to onStop(). onStart() is the counterpart to onStop(); onResume() is the counterpart to onPause(). Initializing something in one pair (e.g., onResume()) and cleaning it up in the other pair (e.g., onStop()) runs the risk of double-initialization or double-cleanup errors.
What's the best way to process the broadcasts that the service sent
while the activity was stopped?
Using sticky broadcast intents from the service and then retrieving them from the activity would be a way to process the broadcasts that the service sent while the activity was stopped. I can only offer that as a possible solution rather than claiming it is the "best way".
http://developer.android.com/reference/android/content/Context.html#sendStickyBroadcast(android.content.Intent)
They have however, been deprecated since API level 21 due to security concerns.
Instead of using Normal broadcast you can use Ordered broadcast (sent with Context.sendOrderedBroadcast). For this along with defining a BroadcastReceiver in your activity you required to define BroadcastReceiver in your manifest with same intentfilter. Only change is while registering BroadcastReceiver in your activity you need to set priority to high, so that when your activity is running and activity's BroadcastReceiver is registered it gets called first, and inside onReceive of this BroadcastReceiver you can use abortBroadcast for getting the BroadcastReceiver called which is defined in your android manifest. Now when your activity is not running the BroadcastReceiver defined in your android manifest will get called. So this way you can have the status and if you wish you can display updates to user by notification even if your activity is not running.
i want to make a notification like BBM connected notification (for android)...
so when i open my app, the notification will appear, and it cant be canceled...
so i use this code
nm=(NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
Notification notification=new Notification(android.R.drawable.stat_notify_more, "this is important", System.currentTimeMillis());
notification.flags = notification.FLAG_NO_CLEAR; //notification never dissapear
Context context=MainActivity.this;
CharSequence title="hello there";
CharSequence detail="this is demo";
Intent intent=new Intent(context,MainActivity.class);
PendingIntent pending=PendingIntent.getActivity(context, 0, intent, 0);
notification.setLatestEventInfo(context, title, detail, pending);
nm.notify(0, notification);
i put that code in public void onCreate(Bundle savedInstanceState)...
so, the notification cant cancel when i click or slide.
and when i close my app, the notification still there.
then i have an idea to use this code :
#Override
protected void onDestroy() {
nm.cancelAll();
}
but, this function never called???
how can i cancel the notification when i close the app?
It might be because onDestroy will not be called immediately when you navigate away with the home button.
Android has callback methods available that work well with notifications etc.
These are called onUserLeaveHint() and onUserInteraction().
The JavaDoc for onUserLeaveHint() states:
Called as part of the activity lifecycle when an activity is about to
go into the background as the result of user choice. For example, when
the user presses the Home key, onUserLeaveHint() will be called, but
when an incoming phone call causes the in-call Activity to be
automatically brought to the foreground, onUserLeaveHint() will not be
called on the activity being interrupted. In cases when it is invoked,
this method is called right before the activity's onPause() callback.
This callback and onUserInteraction() are intended to help activities
manage status bar notifications intelligently; specifically, for
helping activities determine the proper time to cancel a notfication.
I'd suppose you will want to override either one of these; especially onUserLeaveHint() seems a good choice for your purpose.
#Override
protected void onUserLeaveHint()
{
nm.cancelAll();
super.onUserLeaveHint();
}
You can't intercept the event of 'force closing' the application process. Android doesn't support this. When the user does this, the system calls Process.killProcess(int pid) and all resources will be freed. It's just not possible to catch this event and perform tasks before the process is really killed. Maybe a workaround is possible, but it wouldn't be how Android wants it.
There is no guarantee that the method will called. If application will not have enough memory, it can be killed by OS.
There are situations where the system will simply kill the activity's hosting process without calling this method (or any others) in it, so it should not be used to do things that are intended to remain around after the process goes away.
You missed the super.onDestroy
#Override
protected void onDestroy() {
nm.cancelAll();
super.onDestroy();
}
I've got a couple of activities and an intent service which handles GCM incoming messages.
Right now for every push, I'm sending a Notification, and after the user clicks it, he is redirected to appropriate screen.
I would like to alter this behavior that if the app is visible (any activity is in the foreground), instead of the notification a dialog message is shown (with appropriate action).
Any idea how to implement it?
I have 2 ideas but none of them is perfect:
Keep track of every activity in the application, if the activity is visible, don't show notification, but sent an intent to the activity (not nice solution)
register/unregister the second broadcast receiver in each activity's onResume/onPause, "catch" the incoming GCM broadcast (I'm not sure if it is possible).
Any other solutions?
A possible solution (idea 1):
To detect whether your app is running back- or foreground, you can simply set a boolean in onPause/onResume:
#Override
protected void onResume() {
super.onResume();
runningOnBackground = false;
}
#Override
protected void onPause() {
super.onPause();
runningOnBackground = true;
}
When you start a new intent from an notification this method gets called: (if you are using singleTop), with the boolean you can determine what to do in the onNewIntent method.
#Override
protected void onNewIntent (Intent intent){
if(runningOnBackground){
//do this
}
else{
//do that
}
}
Hope it helps!
I didn't test it, but the docs say you can get the number of running activities per each task.
Try to find your application's task among currently running tasks:
ActivityManager acitivityManager = (ActivityManager)
context.getSystemService(Context.ACTIVITY_SERVICE);
// Get the top of running tasks, limit by 100
List<RunningTaskInfo> tasks = acitivityManager.getRunningTasks(100);
for (RunningTaskInfo taskInfo : tasks) {
if (YOUR_PACKAGE_NAME.equals(taskInfo.baseActivity.getPackageName())) {
if (taskInfo.numRunning > 0) {
// Show dialog
} else {
// Show notification
}
break;
}
}
Google added a note on getRunningTasks():
Note: this method is only intended for debugging and presenting task management user interfaces. This should never be used for core logic in an application, such as deciding between different behaviors based on the information found here. Such uses are not supported, and will likely break in the future. For example, if multiple applications can be actively running at the same time, assumptions made about the meaning of the data here for purposes of control flow will be incorrect.
So use it at your own risk.
Also check if GCM broadcasts are ordered. If so, you can "override" your default BroadcastReceiver with the other ones in each Activity. Just play with the priority of IntentFilters. When the BroadcastReceiver with higher priority receives the message, it can abort it's further propagation. For your application this means that when some Activity is running, it registers the receiver which shows the dialog and aborts broadcast. If no activity is active, then your default receiver shows the notification.
I have two buttons StartButton and StopButton on MainActivity.java . When I press StartButton a Service is created and StartButton get disable. On pressing StopButton Service get destroyed and StartButton get enable.
What I wanted to do is to enable my Start Button as Service completed its task; it returns any notification or trigger type event or message value on my MainActivity.java so my Start Button get enable.
Please give me any idea, concept or code to make it easy for me to understand.
To understand the communication between service and application take a look at the examples in the android developer docs.
You can enable and disable your buttons in the onServiceDisconnected() and onServiceConnected() methods.
Keep in mind that the service runs in the same thread as your app by default.
Have you tried,
MyButton.setClickable(false);
It will make the button disabled.
and
MyButton.setClickable(true);
It will enable the button.
However, if you want to hide or show the button, you can use,
MyButton.setVisibiity(VIEW.VISIBLE); and MyButton.setVisibiity(VIEW.INVISIBLE);
Edit- As you want to enable the button, once its task is completed, you could open the mainActivity with a flag value true, something like this,
Intent i= new Intent(getBaseContext(), myActivity.class);
i.putExtra("flag", true);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
getApplication().startActivity(i);
and in the mainActivity, check the value of flag,
Boolean flag;
flag = this.getIntent().getBooleanExtra("flag", false);
if(flag == true) {
MyButton.setClickable(true);
}
But for it, you should keep the value of flag initially to false.
and once you click the button, you could then set it as not clickable.
There can be many ways to achieve this. Let me tell you one with Broadcast Receiver. I hope you are aware of BroadcastReceiver Concepts.
Changes requires in your activity
1) Create a Broadcast receiver as inner class in your activity.
2) Register it with some action, suppose "MY_ACTION".(remember to unregister this receiver on onPause/onDestroy methods)
3) Suppose service completed its task, and you are into onReceive method of Broadcast receiver, now write your code to enable/disable button(i hope you know how to do it)
Changes requires in your Service
1) find out code where you think its task has completed.
2) Create an intent with same action ("MY_ACTION").
3) Broadcast message with sendBroadcast , intent as param. and you are done. :)
let me know if in any point you feel you are stuck ,