Develop Reference

Why does "Home" button call `onDestroy()` in my Android app?

On the Android dev page, it says pressing the "Home" or "Overview" button does not invoke onDestroy,
but in my app, it keeps calling onDestroy. Are there any clues?
(detail situation below)
I've built a simple app that switches from the main activity to a second activity,
but if I press the "Home" or "Overview" button on the second activity, the onDestroy gets called.
So when I go back to my app again, it shows the main activity, not the second activity.
Is this normal?
Should I save the state if I want to go back to the last activity (not the main activity) after pressing the Home or the Overview button and coming back to my app?
Android dev page that I read:
If a new activity or dialog appears in the foreground, taking focus and completely covering the activity in progress, the covered activity loses focus and enters the Stopped state. The system then, in rapid succession, calls onPause() and onStop().
and
Note: When the user taps the Overview or Home button, the system behaves as if the current activity has been completely covered.
So it is supposed to invoke only onPause and onStop, not onDestroy, isn't it?

Finally I found the culprit!
the problem was that I set android:noHistory="true" on the second activity, in the AndroidManifest.xml file.
Making this option true let the activity not leave the history,
so if another activity comes to the foreground and the user pushes the back button, the previous activity(noHistory=true) does not show up.
Similarly, if the user pushes the Home or the Overview button, then the user tries to come back to our app, the last activity(noHistory=true) does not show up either.

You have to put the Code in your Question or we can't help you.
Maybe you are calling finish() in MainActivity after you call startActivity(MainActivity.this, SecondActivity.class) ?
Use the edit-function and show us your code then we can help you more.

Close all Activities when the app returns from being in the background

It is important in my app that when a user presses the home button and the app enters the "Background" the app reverts to the login screen next time it is opened.
I have tried using the
android:noHistory
in the manifest but this means when pressing back on activities it reverts also to the login screen so is no good. I have also tried using
android:clearTaskOnLaunch="true"
in my initial activity but this doesn't seem to have any effect. I don't finish() the first activity so i am not sure why this doesn't work.
Can anyone help with a way of doing this.

I got this working by using
android:clearTaskOnLaunch="true"
Turns out that I didn't have it in my root activity, this was because I have a second login screen which asks for less details depending on if you have logged in before.
Although it works exactly as i want it to, apparently using this "Android" feature is incorrect because i am going "against" android by clearing the tasks (activities) when the home button is pressed and my app should follow someone else opinion of what an "app" should do. Who Knew!

Why don't you use the onPause()-Method? This should be called every time the Activity gets in Background.
So something like:
#Override
public void onPause(){
super.onPause();
finish();
}
Due to the fact that only one Activity of your App can be active at a time you don't have to worry about others still being active.

How to clear activity stack trace on back press event?

I have created an application that has multiple pages and navigation from one to another represents a crucial flow. I don't want the user to be able to press the back button and escape the activity without first warning him and then finally deleting all stack trace such that when the activity is launched again it starts afresh.
As of yet I have been using something similar to the function below :
#Override
public void onBackPressed()
{
this.finish();
Intent int1= new Intent(this, Home.class);
int1.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(int1);
super.onBackPressed();
}
But sometimes when after quitting the application when I launch it again it restarts from some random page or the one from where I quit the application (basically not the home screen from where it is expected to start)
I cannot think of a cleaner way to quit the application other than clearing all the previous activity flags as described in the code.
Any help on the above is appreciated!
EDIT :
Anytime during the flow of my activity if the user presses the back button, I want the control to be thrown back to the main page (clearing all the previous activity stack traces). Such that in case someone re-lanches the application it will re start normally from the main page.

You don't need any of this custom code in onBackPressed(). All you need to do is add this to all of your <activity> definitions in the manifest (except the root activity):
android:noHistory="true"
This ensures that none of your activities (expect the root activity) is recorded in the back stack. When the user clicks the BACK key, it will just return to the root activity.
Another benefit of this is that if the user leaves your app (by clicking HOME or by pulling down the notification bar and clicking on a notification, when he returns to your app it will also just return to your root activity.

Anytime during the flow of my activity if the user presses the back
button, I want the control to be thrown back to the main page
(clearing all the previous activity stack traces).
This can be done just by finishing all the activities as they move forward, except the MainActivity.
Such that in case someone re-lanches the application it will re start
normally from the main page.
Is it like if user is in Activity_5 and uses Home Button and relaunches the app again, MainActicity must appear?
IF so, you can call finish() in onPause() of every Activity except MainActivity
EDIT:
Might not be the perfect solution, but this is what I did to achieve exactly the same(logout in my application):
OnBackPressed() in any activity updates a boolean shared preference say backPressed to true and in onResume() of all the Activities, except MainActivity check its value and finish if true.
#Override
protected void onResume() {
super.onResume();
SharedPreferences mSP = getSharedPreferences(
"your_preferences", 0);
if (mSP .getBoolean("backPressed", false)) {
finish();
}
}

Back Button is used to go back to the previous activity. So i would not override the back button to clear activity stack. I suggest you use a Action Bar for this purpose. Navigate to Home Screen of the application using the application icon.
http://developer.android.com/guide/topics/ui/actionbar.html
Also check this link and comments below the answer by warrenfaith
android - onBackPressed() not working for me

#Override
public void onBackPressed()
{
moveTaskToBack(true);
android.os.Process.killProcess(android.os.Process.myPid());
System.exit(1);
}
you can use that code, it's work for me!

Activity not closing properly

I am calling one activity on click of status bar notification which is having a Complete button. on click of btn. i have folllowing code -
public void completeTask(){
taskDBAdapter.deleteReminder(rowId);
taskDBAdapter.close();
Intent intent = new Intent(this, TaskManagerActivity.class);
startActivity(intent);
finish();
}
whhen i click complete btn new activity (TaskManagerActivity) gets opened properly.But if i reopen my application it still tries to open this activity and not my default landing activity. Any help on this.??
EDIT -
I have tried repositioning my finish() statement . Still its not working.
EDIT 1.1 -
Ok I will provide some details here. Assume my app has two activities
Main Activity
Notification Activity
My app create some notification to display on Status bar. So as soon as i click on status bar Notification actvty will open. Now there is a button called Complete on click of which the code given will fire and main activity (in the code TaskManagerActivity.class) will open. But after I press back button in my app and again reopen it , it opens the notification activity when it should have fired the main activity (as it is launching activity).
Thanks,
Ray

That's the default way android functions. If you press the home button and then open your app again, it will restore the apps previous state (unless it has killed the apps processes and activities due to memory constraints). So you are not actually restarting your app but only restoring it.
If you wanna quit the app, then press the back button. Now when you re-open the app, the original activity will be launched.
Do not modify this behavior. It is the default system behavior and users expect it to work this way. Your app is fine :-)

- First of all the behavior which you are experiencing is the way Android is made to function, moreover when a user gets a call while this app is open, after finishing the app he will definitely want to get back to the state where he left the application.
Still if you want it that way, here it is.....
- Make sure your application has only single instance of it running, by using android:launchMode="singleTask", or android:launchMode="singleInstance"
- Then finish() your Activity at onPause().
#Override
void onPause()
{
super.onPause();
finish();
}

Is there a way to write code to go to the previous activity?

Right now in my android app a user presses a button to go to another activity, and then must press the back button on android to return to the previous activity. Can I have a button on my app and write code to go to the previous activity?

As the easiest way, you code write a code where your current activity is closed on a particular event, say on a button press. the method to be called is finish()
This way, when your current activity is finished, you are taken back to your previous activity.

Yes Ofcourse. : See the vogella article