CODEWITHSUNDEEP
androidandroid-activitystack
Jaya Mayu
Jaya Mayu

Reputation: 17257

Android: Clear Activity Stack

I'm having several activities in my application. and flow is very complicated. When I click the Logout application navigates to login Screen and from there user can exit by cancel button (calling system.exit(0) )

when I exit or back button, the system invokes an activity from stack :( how can I clear all the activities in the stack when I reach Login screen? calling finish() is not practical as there are so many activities and some activities should no be closed when they are active such as native camera invoking activity.

validateuser logoutuser = new validateuser();
logoutuser.logOut();
Intent loginscreen = new Intent(homepage.this, Login2.class);
(homepage.this).finish();
loginscreen.setFlags( Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NO_HISTORY);
startActivity(loginscreen);

Upvotes: 147

Views: 127605

Answers (12)

Rohit Sahu
Rohit Sahu

Reputation: 1

public void logout(View view) {

    Intent intent = new Intent(Current.this, Target.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
    startActivity(intent);

}

This worked! While searching on why this works I found this "Start the activity in a new task, and clear any existing tasks with the same affinity."

I could only found this Document relating to clearing the back stack or the task. Task with the same affinity is also a bit confusing.

For Android Studio Iguana Tested on android api level 34, android upside down cake(Android 14.0)

Upvotes: 0

Raviraj
Raviraj

Reputation: 926

Intent intent = new Intent(LoginActivity.this,MainActivity.class); intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK); startActivity(intent); finish();

Upvotes: 0

Gibolt
Gibolt

Reputation: 47297

Using Kotlin:

You can set the flag directly using setter method. In Kotlin or is the replacement for the Java bitwise or |.

intent.flags = FLAG_ACTIVITY_NEW_TASK or FLAG_ACTIVITY_CLEAR_TASK

If you plan to use this regularly, create an Intent extension function

fun Intent.clearStack() {
    flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
}

You can then directly call this function before starting the intent

intent.clearStack()

Upvotes: 4

BYISHIMO Audace
BYISHIMO Audace

Reputation: 595

For Xamarin Developers, you can use:

intent.SetFlags(ActivityFlags.NewTask | ActivityFlags.ClearTask);

Upvotes: 3

maXp
maXp

Reputation: 1468

This decision works fine: 

intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);

But new activity launch long and you see white screen some time. If this is critical then use this workaround:

public class BaseActivity extends AppCompatActivity {

    private static final String ACTION_FINISH = "action_finish";

    private BroadcastReceiver finisBroadcastReceiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        registerReceiver(finisBroadcastReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                finish();
            }
        }, new IntentFilter(ACTION_FINISH));
    }

    public void clearBackStack() {
        sendBroadcast(new Intent(ACTION_FINISH));
    }

    @Override
    protected void onDestroy() {
        unregisterReceiver(finisBroadcastReceiver);
        super.onDestroy();
    }
}

How use it:

public class ActivityA extends BaseActivity {

    // Click any button
    public void startActivityB() {
        startActivity(new Intent(this, ActivityB.class));
        clearBackStack();
    }
}

Disadvantage: all activities that must be closed on the stack must extends BaseActivity

Upvotes: 4

Kevin Lee
Kevin Lee

Reputation: 2347

I noted that you asked for a solution that does not rely on finish(), but I wonder if this may help nonetheless.

I tracked whether an exit flag is raised with a static class variable, which survives the entire app lifespan. In each relevant activity's onResume(), use

@Override
public void onResume() {
    super.onResume();
    if (ExitHelper.isExitFlagRaised) {
        this.finish();
    }
}

The ExitHelper class

public class ExitHelper {
    public static boolean isExitFlagRaised = false;
}

Let's say in mainActivity, a user presses a button to exit - you can set ExitHelper.isExitFlagRaised = true; and then finish(). Thereafter, other relevant activities that are resumed automatically will be finished as well.

Upvotes: 3

Mohd Sakib Syed
Mohd Sakib Syed

Reputation: 1769

Intent intent = new Intent(LoginActivity.this, Home.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);  //It is use to finish current activity
startActivity(intent);
this.finish();

Upvotes: 4

Hiren Patel
Hiren Patel

Reputation: 52810

Clear Activity Backstate by below code:

Intent intent = new Intent(Your_Current_Activity.this, Your_Destination_Activity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK |Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);

Done

Upvotes: 12

Cynichniy Bandera
Cynichniy Bandera

Reputation: 6103

Most of you are wrong. If you want to close existing activity stack regardless of what's in there and create new root, correct set of flags is the following:

intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);

From the doc:

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.

Upvotes: 369

whlk
whlk

Reputation: 15645

Here is a simple helper method for starting a new activity as the new top activity which works from API level 4 up until the current version 17:

static void startNewMainActivity(Activity currentActivity, Class<? extends Activity> newTopActivityClass) {
    Intent intent = new Intent(currentActivity, newTopActivityClass);
    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
        intent.addFlags(0x8000); // equal to Intent.FLAG_ACTIVITY_CLEAR_TASK which is only available from API level 11
    currentActivity.startActivity(intent);
}

call it like this from your current activity:

startNewMainActivity(this, MainActivity.class);

Upvotes: 16

David Olsson
David Olsson

Reputation: 8225

When you call startActivity on the last activity you could always use

Intent.FLAG_ACTIVITY_CLEAR_TOP

as a flag on that intent.

Read more about the flag here.

Upvotes: 30

Prashant Gami
Prashant Gami

Reputation: 1580

In my case, LoginActivity was closed as well. As a result, 

Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_CLEAR_TASK

did not help.

However, setting 

Intent.FLAG_ACTIVITY_NEW_TASK

helped me.

Upvotes: 3

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