New Intent starts new instance with Android launchMode singleTop

Question

I have Activity A with android launchMode  singleTop  in the manifest   If I go to Activity B  C  and D there I have menu shortcuts to return to my applications root activity  A    The code looks like this   Intent myIntent   new Intent getBaseContext    MainActivity class   startActivity myIntent     However  instead of returning to the already existing instance A of my MainActivity class it creates a new instance -  it goes to onCreate   instead of onNewIntent     This is not the expected behavior  right

User · Answer

What actually worked for me in the end was this   Intent myIntent   new Intent getBaseContext    MainActivity class   myIntent setFlags Intent FLAG ACTIVITY CLEAR TOP   startActivity myIntent

User · Answer

Firstly  Stack structure can be examined  For the launch mode singleTop If an instance of the same activity is already on top of the task stack  then this instance will be reused to respond to the intent     All activities are hold in the stack  first in last out   so if your current activity is at the top of stack and if you define it in the manifest file as singleTop  android name   ActivityA  android launchMode  singleTop    if you are in the ActivityA recreate the activity it will not enter onCreate will resume onNewIntent   and you can see by creating a notification  Not If you do not implement  onNewIntent Intent   you will not get new intent   Intent activityMain   new Intent ActivityA this                          ActivityA class                    activityMain setFlags Intent FLAG ACTIVITY NEW TASK                           Intent FLAG ACTIVITY SINGLE TOP                   startActivity activityMain            Override         protected void onNewIntent Intent intent                 super onNewIntent intent                notify  onNewIntent                       private void notify String methodName                 String name   this getClass   getName                String   strings   name split                      Notification noti   new Notification Builder this                       setContentTitle methodName        strings strings length - 1                        setAutoCancel true  setSmallIcon R drawable ic launcher                       setContentText name  build                NotificationManager notificationManager    NotificationManager  getSystemService NOTIFICATION SERVICE               notificationManager notify  int  System currentTimeMillis    noti

User · Answer

Quote from the documentation       The  standard  and  singleTop  modes   differ from each other in just one   respect  Every time there s new intent   for a  standard  activity  a new   instance of the class is created to   respond to that intent  Each instance   handles a single intent  Similarly  a   new instance of a  singleTop  activity   may also be created to handle a new   intent  However  if the target task   already has an existing instance of   the activity at the top of its   stack  that instance will receive   the new intent  in an onNewIntent     call   a new instance is not created    I m not 100  sure what  already has an existing instance of the activity at the top of its stack  means  but perhaps your activity isn t meeting this condition   Would singleTask or singleInstance work for you   Or perhaps you could try setting FLAG ACTIVITY SINGLE TOP on the intent you are creating to see if that makes a difference  although I don t think it will

User · Answer

You can return to the same existing instance of Activity with android launchMode  singleInstance   in the manifest  When you return to A from B  may be needed finish   to destroy B

User · Answer

This should do the trick    lt activity     android launchMode  singleTop    gt    When you create an intent to start the app use   Intent intent  new Intent context  YourActivity class   intent setFlags Intent FLAG ACTIVITY NEW TASK   Intent FLAG ACTIVITY SINGLE TOP     This is that should be needed

User · Answer

This is because the original A activity is already being destroyed by the time you start it from B  C or D  Therefore  onCreate will be called in stead of onNewIntent    One way of solving this is to always destroy the existing A using FLAG ACTIVITY CLEAR TASK   FLAG ACTIVITY NEW TASK conjunction when startActivity  before starting a new A  so onCreate will always be called  and you put the code of onNewIntent   into onCreate by checking if getIntent   is the intent you started with

[android] New Intent() starts new instance with Android: launchMode="singleTop"

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