Best way to handle activity state - android

I'm making an app that shows another activity when I correctly login however in the home screen when I pressed back and then returned to the app the login activity showed.
I was able to avoid this overriding the onBackPressed this way:
public void onBackPressed()
moveTaskToBack(true);
}
Is this the best way to do it? Is there a more proper way to keep the state of the application when I exit it?

In your login activity after starting intent call finish()
finish destroy your activity and avoid to run it again automatically.

Your issue is that you kept LoginActivity in stack. so when you press back it will kill MainActivity(after login) and since LoginAcitivity still there. it will be shown again. best is to kill LoginAcitivty after starting new activity.
call this in LoginActivity:
Intent intent = new Intent(context, MainActivity.class);
startActivity(intent);
finish();

As you question I understand, you want to clear the entire history stack and start a new activity. For this, in API level 11 a new Intent Flag was added which is: Intent.FLAG_ACTIVITY_CLEAR_TASK
Just to clarify, use this:
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
For API <=10 now one can use IntentCompat class for the same. One can use IntentCompat.FLAG_ACTIVITY_CLEAR_TASK flag to clear task. So you can support pre API level 11 as well.

Related

When do I use addFlags or setFlags for the purpose of removing activities in stack?

I have OnBoard Activity and Login Activity. In LoginActivity after successful login I am trying to clear onboard activity using below code:
startActivity(new Intent(context, HomeActivity.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP|Intent.FLAG_ACTIVITY_CLEAR_TASK));
I've even tried Intent.FLAG_ACTIVITY_NO_HISTORY but it's also not working. So what should I do?
I am assuming that the app starts with OnboardActivity and that starts LoginActivity and then you want to clear them both and launch HomeActivity?
If that is the case, I would do it this way:
OnboardActivity launches LoginActivity using startActivityForResult().
LoginActivity returns a result that indicates if the login was successful or not and calls finish(). LoginActivity is no longer in the task.
OnboardActivity checks the result in OnActivityResult() and, if the login was successful, launches HomeActivity (no flags needed) and calls finish() on itself.
At this point, both LoginActivity and OnboardActivity are gone, and HomeActivity is the only Activity in the task.
Try below code:
Intent intent = new Intent(context, HomeActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
I would say go with the finishAffinity() before moving to onboard activity. There is no need to set any flags. Because this method kills all activities in the stack and current activity as well
There is no need to use FLAGS. Even though you want to understand, Check this
There are two ways to finish Current Activity (LoginActivity in your case) and move to Next Activity (OnBoard in your case).:
Call finish() before starting Second Activity. It will destroy current activity.
Call finishAffinity(); before starting Second Activity. It will destroy stack of all previous activity.
Hope it will helps you.

How to Clear the activity stack SDK < 11

I need to clear the activity stack. All the activity except the current one in SDK 8. I want after logout from any activity I can reach to the Login Activity and All previous Activity will get Removed from the activity stack.
I have tried this solution
Intent i = new Intent(BaseActivity.this, LoginActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP
| Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(i);
But it is not working. I can't use finish() because user can logout from any activity.
Your Help is Highly appreciable.
Just use this flag on its own Intent. FLAG_ACTIVITY_CLEAR_TASK
Use This
Normally when we launch new activity, it’s previous activities will be kept in a queue like a stack of activities. So if you want to kill all the previous activities, just follow these methods
Intent i = new Intent(OldActivity.this, NewActivity.class);
// set the new task and clear flags
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK)
startActivity(i);
I have got two Beautiful solution of my problem.
SOLUTION 1:
One is by using Broadcast Receiver. That I can broadcast a message to all my activity and onRecive() I can finish all my activity. As this Link says.
SOLUTION 2 (A Much Easier way):
Second is by managing a flag in ShearedPrefrences or in Application Activity. In starting of app (on splash screen) set the flag = false; OnLogout click event, just set the flag true and in OnResume() of every activity check if flag is true then call finish().
It works like a charm :) And please If you can't answer at least don't abuse the question.

How to start a new Intent that will clear all other activities?

To lay it out as simply as possible. My user enters the app through Activity A. They "login" and then Activity B is started, and Activity A is finished using finish() so that the users can't get back to the login screen by pressing back from Activity B. Now in Activity B, they move to Activity C, and in activity C, I want them to start a new intent that will start activity A, but "kill"/"finish" all other activities. The only way I can think of doing this is using an Intent Flag. so far I've come up with:
Intent intent = new Intent(getActivity(), ActivityA.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET|Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);
startActivity(intent);
But the code above doesn't work. I still see that my app had a savedInstanceState in Activity B. Hence something like CLEAR_TASK won't work for me case.
EDIT: Also, is there an easy way to tell have many "tasks" your app has opened currently?
Note: There seems to be other flags that may help, but they were added in API 11, and I need to support API 10.
Flag combos I've tried:
Doesn't work
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET|Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);
Doesn't work
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
You need to use IntentCompat. like
import android.support.v4.content.IntentCompat;
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK |IntentCompat.FLAG_ACTIVITY_CLEAR_TASK);
Check whether the below answer helps you:
http://www.hrupin.com/2011/10/how-to-finish-all-activities-in-your-android-application-through-simple-call

Android SingleTask not working

I have a multiple activities in my application. Two of them are a LoginActivity and the second one is a SettingsActivity. The user logs into the Settings activity and logs out of the application from the SettingsActivity. The flow of the application is LoginActivity -> HomeActivity -> SettingsActivity . The user calls the logout from the application in the Settings Activity. I call finish on the Settings activity and create an intent to the LoginActivity. This works fine, but when i press the back on the loginactivity the home activity appears. I want that once the LoginActivity appears the back button should take the application out of the application. How can i do this ?
The answer lies in FLAG_ACTIVITY_CLEAR_TOP.
All you need to do is set the flag to your intent like shown below
Intent i = new Intent(this, LoginActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
finish();
That should pretty much do what you want it to do.
I believe this is what you are looking for:
How to clear the Android Stack of activities?
I wouldnt get too hung up on the fact that it doesnt actually finish() your LoginActivity - this is actually a pretty normal pattern to follow.
I had to use .FLAG_ACTIVITY_CLEAR_TASK for this to work . I read this is supported after API version 11, will these do for all previous versions. Secondly how can i use these from the Manifest file and not the java code ?
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK|Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);

Removing an activity from the history stack

My app shows a signup activity the first time the user runs the app, looks like:
ActivitySplashScreen (welcome to game, sign up for an account?)
ActivitySplashScreenSignUp (great, fill in this info)
ActivityGameMain (main game screen)
so the activities launch each other in exactly that order, when the user clicks through a button on each screen.
When the user goes from activity #2 to #3, is it possible to wipe #1 and #2 off the history stack completely? I'd like it so that if the user is at #3, and hits the back button, they just go to the homescreen, instead of back to the splash screen.
I think I can accomplish this with tasks (ie. start a new task on #3) but wanted to see if there was simpler method,
Thanks
You can achieve this by setting the android:noHistory attribute to "true" in the relevant <activity> entries in your AndroidManifest.xml file. For example:
<activity
android:name=".AnyActivity"
android:noHistory="true" />
You can use forwarding to remove the previous activity from the activity stack while launching the next one. There's an example of this in the APIDemos, but basically all you're doing is calling finish() immediately after calling startActivity().
Yes, have a look at Intent.FLAG_ACTIVITY_NO_HISTORY.
This is likely not the ideal way to do it. If someone has a better way, I will be looking forward to implementing it. Here's how I accomplished this specific task with pre-version-11 sdk.
in each class you want to go away when it's clear time, you need to do this:
... interesting code stuff ...
Intent i = new Intent(MyActivityThatNeedsToGo.this, NextActivity.class);
startActivityForResult(i, 0);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == R.string.unwind_stack_result_id) {
this.setResult(R.string.unwind_stack_result_id);
this.finish();
}
}
then the one that needs to set off the chain of pops from the stack needs to just call this when you want to initiate it:
NextActivity.this.setResult(R.string.unwind_stack_result_id);
NextActivity.this.finish();
Then the activities aren't on the stack!
Remember folks, that you can start an activity, and then begin cleaning up behind it, execution does not follow a single (the ui) thread.
One way that works pre API 11 is to start ActivityGameMain first, then in the onCreate of that Activity start your ActivitySplashScreen activity. The ActivityGameMain won't appear as you call startActivity too soon for the splash.
Then you can clear the stack when starting ActivityGameMain by setting these flags on the Intent:
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
You also must add this to ActivitySplashScreen:
#Override
public void onBackPressed() {
moveTaskToBack(true);
}
So that pressing back on that activity doesn't go back to your ActivityGameMain.
I assume you don't want the splash screen to be gone back to either, to achieve this I suggest setting it to noHistory in your AndroidManifest.xml. Then put the goBackPressed code in your ActivitySplashScreenSignUp class instead.
However I have found a few ways to break this. Start another app from a notification while ActivitySplashScreenSignUp is shown and the back history is not reset.
The only real way around this is in API 11:
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
I use this way.
Intent i = new Intent(MyOldActivity.this, MyNewActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK)
startActivity(i);
I know I'm late on this (it's been two years since the question was asked) but I accomplished this by intercepting the back button press. Rather than checking for specific activities, I just look at the count and if it's less than 3 it simply sends the app to the back (pausing the app and returning the user to whatever was running before launch). I check for less than three because I only have one intro screen. Also, I check the count because my app allows the user to navigate back to the home screen through the menu, so this allows them to back up through other screens like normal if there are activities other than the intro screen on the stack.
//We want the home screen to behave like the bottom of the activity stack so we do not return to the initial screen
//unless the application has been killed. Users can toggle the session mode with a menu item at all other times.
#Override
public void onBackPressed() {
//Check the activity stack and see if it's more than two deep (initial screen and home screen)
//If it's more than two deep, then let the app proccess the press
ActivityManager am = (ActivityManager)this.getSystemService(Activity.ACTIVITY_SERVICE);
List<RunningTaskInfo> tasks = am.getRunningTasks(3); //3 because we have to give it something. This is an arbitrary number
int activityCount = tasks.get(0).numActivities;
if (activityCount < 3)
{
moveTaskToBack(true);
}
else
{
super.onBackPressed();
}
}
In the manifest you can add:
android:noHistory="true"
<activity
android:name=".ActivityName"
android:noHistory="true" />
You can also call
finish()
immediately after calling startActivity(..)
Just set noHistory="true" in Manifest file.
It makes activity being removed from the backstack.
It is crazy that no one has mentioned this elegant solution. This should be the accepted answer.
SplashActivity -> AuthActivity -> DashActivity
if (!sessionManager.isLoggedIn()) {
Intent intent = new Intent(context, AuthActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
context.startActivity(intent);
finish();
} else {
Intent intent = new Intent(context, DashActivity.class);
context.startActivity(intent);
finish();
}
The key here is to use intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY); for the intermediary Activity. Once that middle link is broken, the DashActivity will the first and last in the stack.
android:noHistory="true" is a bad solution, as it causes problems when relying on the Activity as a callback e.g onActivityResult. This is the recommended solution and should be accepted.
It's too late but hope it helps. Most of the answers are not pointing into the right direction. There are two simple flags for such thing.
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
From Android docs:
public static final int FLAG_ACTIVITY_CLEAR_TASK
Added in API level 11
If set in an Intent passed to Context.startActivity(), this flag will cause any existing task that would be associated with the
activity to be cleared before the activity is started. That is, the
activity becomes the new root of an otherwise empty task, and any old
activities are finished. This can only be used in conjunction with
FLAG_ACTIVITY_NEW_TASK.
Just call this.finish() before startActivity(intent) like this-
Intent intent = new Intent(ActivityOne.this, ActivityTwo.class);
this.finish();
startActivity(intent);
Removing a activity from a History is done By setting the flag before the activity You Don't want
A->B->C->D
Suppose A,B,C and D are 4 Activities if you want to clear B and C then
set flag
intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
In the activity A and B
Here is the code bit
Intent intent = new Intent(this,Activity_B.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
startActivity(intent);
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
super.finishAndRemoveTask();
}
else {
super.finish();
}
Here I have listed few ways to accomplish this task:
Go to the manifest.xml- and put android:noHistory="true", to remove the activity from the stack.
While switching from present activity to some other activity, in intent set flag as (Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK). It is demonstrated in the example below.
Intent intent = new Intent(CurrentActivity.this, HomeActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
Intent.FLAG_ACTIVITY_CLEAR_TASK)
startActivity(intent);here
Note :Putting the intent flags can cause blank screen for sometime (while switching activity).
Try this:
intent.addFlags(Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY)
it is API Level 1, check the link.

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