I have an application that contains many game screens, each is its own activity. Some of these game screens will use timers to initiate some functionality. The problem I am having is when the user backs out of one of these game screens, the timers are still running in the background. I know this because when I leave to the main menu the timer loads up the losing screen because the timer and activity were still running in the background process. I simply want to kill the activity if the user hits the phone back button (Not a button I have created but the devices back button).
This is the current method I use to try and accomplish this:
#Override
public void onBackPressed() {
super.onBackPressed();
this.finish();
}
It does not kill the activity.
EDIT:
I Should mention that stopping the timers does work but for some of my screens the win or lose conditions are done when a variable hits a certain number. For example, I have one screen that when an enemy escapes the view of the player a variable goes up by 1 when this hits 5 the player loses. This is not done on a timer, so because the activity is still running, the variable hits 5 and the losing screen is loaded when I am not on that game screen anymore.
Only the visible Activity will receive that finish() command. You need to start and stop your timers onResume and onPause
First of all, remove
super.onBackPressed();
And add
yourActivity.this.finish();
Let me know if that helps :)
I'm currently developing a custom camera application which takes a video using MediaRecorder for 5 seconds. I have implemented a number countdown overlay which counts down from 5.
My problem is that I am not 100% sure how to implement surface methods and pause/resume methods. If I close my app half way through recording and then open it again, the app freezes, shows a black screen, and eventually crashes.
Should onPause and surfaceDestroyed be used in unison? (Same question applies to onResume and surfaceCreated) How does surfaceChanged fit into this?
I'm guessing I need to find a way to restart my CameraActivity every time it resumes. (As I don't want it resuming half way through a countdown).
You should look at Activity lifecycle onPause and onResume for creating and destroying camera.
http://developer.android.com/training/basics/activity-lifecycle/pausing.html#Pause
Over the past months I have been developing a versatile real-time game engine, and I have learned a lot, but I still feel very naive when it comes to the application life cycle. Specifically, I am trying to implement an Activity which can be shuffled in to the background by the user, then properly resumed.
My current architecture is as such: I have a an XML menu launcher activity which can create a real-time Game activity using intent. Relevant data in this Game activity is referenced through static data structures and variables. The Game activity creates worker threads in the onSurfaceCreate() callback of my SurfaceView object.
When a user presses the back button, the activity is destroyed, and they are sent back to the XML menu in the launcher activity. Fine, good for now. When the user presses the home button, the Activity is sent to the background. OK, great. My problems arise when the user tries to find their way back in the Game activity once is has been sent to the background. When the user touches the launcher icon, the Game is destroyed and the menu is re-launched. Also, when the user resumes the game through the task manager, the onSurfaceCreate() callback fires and the worker threads are started, but the game is frozen.
So, I have two questions. First, how do I resume my activity through the launcher icon, instead of re-launching the game? Second, when I resume my activity, what actions are necessary to restart my worker threads while persisting the game data?
Thanks!
EDIT: By request, I am including some code below. My onSurfaceCreate is a little bit complicated, it sends a message to another thread, which then implements the callback. I have verified that this implementation function fires when the Game activity is resumed.
protected void surfaceCreate()
{
Log.e(TAG, "surfaceCreate");
Thread gameThread = createGameThread();
gameThread.start();
}
protected final void onResume()
{
super.onResume();
resume();
}
protected final void onPause()
{
super.onPause();
pause();
}
These cryptic pause() and resume() methods simply set a boolean variable which prevents some game logic from being executed, they do nothing to hinder the worker threads, which should continue looping.
EDIT: Thanks Mohammad, for solving my first (although smaller) problem. It turns out that the launcher icon behaves differently when not connected by USB to the IDE. The second problem remains unresolved.
EDIT: All working! The second problem turned out to be an issue unique to my code, I apologize for that. I hope that this question can still be useful for those dealing with the launcher and IDEs.
There are multiple possible problems/solutions listed in this post. This includes misunderstanding of activity lifecycle and launchMode settings.
First, how do I resume my activity through the launcher icon, instead
of re-launching the game?
You are most likely missing definition for your onResume() and onPause() methods. Examples are here:
http://developer.android.com/training/basics/activity-lifecycle/pausing.html
Straight from the API:
onPause() Called as part of the activity lifecycle when an
activity is going into the background, but has not (yet) been killed.
onResume() Called after onRestoreInstanceState(Bundle),
onRestart(), or onPause(), for your activity to start interacting with
the user.
Check the Android Activity Lifecycle out:
http://developer.android.com/reference/android/app/Activity.html
One theory on your issue may be is that you're most likely going to onStop() (by hitting the home button) and the Android OS is looking for your onRestart(), but can't find it hence freezing/restarting.
Second, when I resume my activity, what actions are necessary to
restart my worker threads while persisting the game data?
Careful how you use the word restart. You want to pause and resume the application (not restart). Save data in onPause() (use a database or any other save feature you'd like). Load data in onResume(). Although, the activity should resume as normal if you just fill up these methods.
Now, if you want to save state for when you restart the application, you should save states in onStop() and/or onDestroy(). You should load states in onStart(). In order to save states, you can check this out:
https://stackoverflow.com/a/151940/2498729
For those using Eclipse (or any other IDE to run/test your application):
From what have you described you probably have overridden
android:launchMode in AndroidManifest.xml or if you are testing by
"run as" from Eclipse try exiting the application after installing and
auto-starting. Then start again from the emulator and test the Home
button behavior. I suppose this is because Android does not put
Activities on the OS stack when started from Eclipse and then the Home
button behavior is not as usual. If this does not solve your problem,
try reading
http://developer.android.com/guide/topics/fundamentals.html#lmodes.
I had launchMode set in my StartupActivity. THen I removed that (it
was set to "singleTask", it behaves like I want it; the app is
"resumed" to the Activity I expect, ie not StartupActivity but
MainActivity.
Source:
https://stackoverflow.com/a/1619461/2498729
http://developer.android.com/guide/topics/manifest/activity-element.html
According to this:
https://stackoverflow.com/a/3002890/2498729
You should change your andoird:launchMode to "Standard" (or "default").
Standard: A > B > HOME > B (what you want)
SingleTask: A > B > HOME > A (what you don't want)
I have an app that responds to Internet message by creating a new Activity and user has 20 seconds to respond.
The problem is when the app is running on background.
I can show a notification, but when the user returns to the App the new Activity isn't started.
Is there any way to start an Activity even when the App isn't on foreground (without the activity getting focus) or any easy workaround where the activity would start right after returning to the app? (which would be worse solution, cause I would have to rework the sync timer :))
Thanks
Take a look at the Activity life cycle
Here you have the onResume() method you can override and do something before the Activity itself is shown. From there you could do some kind of check that you are returning from a notification or a check on that the user has to answer something now and launch a new Activity from the onResume() method.
Here's my problem: I start a media player, and if I start a new intent, or leave the app and go back to it..
mp.stop;
..wont work (mp is my media player variable).
is there anyway to fix this?
Bonus to whoever can tell me how to link it up to a widget.
You always must call mp.release() in your Activity's onDestroy(). It is also recommended to at least call mp.pause() in on onPause() Activity's method.
If you want playback to continue outside of Activity lifecycle (after onPause()/onStop()/onDestroy()) you have to create Service and play audio content from there.