How to get current foreground activity context in android

Question

Whenever my broadcast is executed I want to show alert to foreground activity

User · Answer

Update 3  There is an official api added for this  please use ActivityLifecycleCallbacks instead

User · Answer

Knowing that ActivityManager manages Activity  so we can gain information from ActivityManager  We get the current foreground running Activity by  ActivityManager am    ActivityManager context getSystemService Context ACTIVITY SERVICE   ComponentName cn   am getRunningTasks 1  get 0  topActivity    UPDATE 2018 10 03 getRunningTasks   is DEPRECATED  see the solutions below   This method was deprecated in API level 21  As of Build VERSION CODES LOLLIPOP  this method is no longer available to third party applications  the introduction of document-centric recents means it can leak person information to the caller  For backwards compatibility  it will still return a small subset of its data  at least the caller s own tasks  and possibly some other tasks such as home that are known to not be sensitive

User · Answer

I m like 3 years late but I ll answer it anyway in case someone finds this like I did   I solved this by simply using this       if  getIntent   toString   contains  MainActivity                 Do stuff if the current activity is MainActivity         Note that  getIntent   toString    includes a bunch of other text such as your package name and any intent filters for your activity  Technically we re checking the current intent  not activity  but the result is the same  Just use e g  Log d  test   getIntent   toString     if you want to see all the text  This solution is a bit hacky but it s much cleaner in your code and the functionality is the same

User · Answer

I don t like any of the other answers  The ActivityManager is not meant to be used for getting the current activity  Super classing and depending on onDestroy is also fragile and not the best design   Honestly  the best I have came up with so far is just maintaining an enum in my Application  which gets set when an activity is created   Another recommendation might be to just shy away from using multiple activities if possible  This can be done either with using fragments  or in my preference custom views

User · Answer

A rather simple solution is to create a singleton manager class  in which you can store a reference to one or more Activities  or anything else you want access to throughout the app   Call UberManager getInstance   setMainActivity  activity    in the main activity s onCreate   Call UberManager getInstance   getMainActivity    anywhere in your app to retrieve it   I am using this to be able to use Toast from a non UI thread    Make sure you add a call to UberManager getInstance   cleanup    when your app is being destroyed   import android app Activity   public class UberManager       private static UberManager instance   new UberManager         private Activity mainActivity   null       private UberManager                     public static UberManager getInstance                 return instance             public void setMainActivity  Activity mainActivity                 this mainActivity   mainActivity             public Activity getMainActivity                 return mainActivity             public void cleanup                 mainActivity   null

User · Answer

Note  An official API was added in API 14  See this answer https   stackoverflow com a 29786451 119733   DO NOT USE PREVIOUS  waqas716  answer   You will have memory leak problem  because of the static reference to the activity  For more detail see the following link http   android-developers blogspot fr 2009 01 avoiding-memory-leaks html  To avoid this  you should manage activities references  Add the name of the application in the manifest file    lt application     android name   MyApp             lt  application gt    Your application class      public class MyApp extends Application           public void onCreate                   super onCreate                       private Activity mCurrentActivity   null          public Activity getCurrentActivity                  return mCurrentActivity                    public void setCurrentActivity Activity mCurrentActivity                 this mCurrentActivity   mCurrentActivity                  Create a new Activity    public class MyBaseActivity extends Activity       protected MyApp mMyApp       public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           mMyApp    MyApp this getApplicationContext              protected void onResume             super onResume            mMyApp setCurrentActivity this             protected void onPause             clearReferences            super onPause              protected void onDestroy                     clearReferences            super onDestroy               private void clearReferences            Activity currActivity   mMyApp getCurrentActivity            if  this equals currActivity               mMyApp setCurrentActivity null             So  now instead of extending Activity class for your activities  just extend MyBaseActivity  Now  you can get your current activity from application or Activity context like that    Activity currentActivity     MyApp context getApplicationContext    getCurrentActivity

User · Answer

I could not find a solution that our team would be happy with so we rolled our own  We use ActivityLifecycleCallbacks to keep track of current activity and then expose it through a service  More details here  https   stackoverflow com a 38650587 10793

User · Answer

I did the Following in Kotlin   Create Application Class Edit the Application Class as Follows  class FTApplication  MultiDexApplication     override fun attachBaseContext base  Context         super attachBaseContext base      MultiDex install this     init       instance   this    val mFTActivityLifecycleCallbacks   FTActivityLifecycleCallbacks    override fun onCreate         super onCreate        registerActivityLifecycleCallbacks mFTActivityLifecycleCallbacks     companion object       private var instance  FTApplication    null      fun currentActivity    Activity             return instance   mFTActivityLifecycleCallbacks currentActivity              Create the ActivityLifecycleCallbacks class   class FTActivityLifecycleCallbacks  Application ActivityLifecycleCallbacks    var currentActivity  Activity    null  override fun onActivityPaused activity  Activity         currentActivity   activity    override fun onActivityResumed activity  Activity         currentActivity   activity    override fun onActivityStarted activity  Activity         currentActivity   activity    override fun onActivityDestroyed activity  Activity        override fun onActivitySaveInstanceState activity  Activity   outState  Bundle        override fun onActivityStopped activity  Activity        override fun onActivityCreated activity  Activity   savedInstanceState  Bundle         currentActivity   activity       you can now use it in any class by calling the following  FTApplication currentActivity

User · Answer

The answer by waqas716 is good  I created a workaround for a specific case demanding less code and maintenance     I found a specific work around by having a static method fetch a view from the activity I suspect to be in the foreground  You can iterate through all activities and check if you wish or get the activity name from martin s answer   ActivityManager am    ActivityManager context getSystemService Context ACTIVITY SERVICE   ComponentName cn   am getRunningTasks 1  get 0  topActivity     I then check if the view is not null and get the context via getContext     View v   SuspectedActivity get view     if v    null           an example for using this context for something not         permissible in global application context       v getContext   startActivity new Intent  rubberduck com activities SomeOtherActivity

User · Answer

For backwards compatibility   ComponentName cn  ActivityManager am    ActivityManager  getApplicationContext   getSystemService Context ACTIVITY SERVICE   if  android os Build VERSION SDK INT  gt   android os Build VERSION CODES M        cn   am getAppTasks   get 0  getTaskInfo   topActivity    else         noinspection deprecation     cn   am getRunningTasks 1  get 0  topActivity

User · Answer

lockwobr Thanks for update     This does not work 100  of the time in api version 16  if you read the   code on github the function  currentActivityThread  was change in   Kitkat  so I want to say version 19ish  kind of hard to match api   version to releases in github    Having access to the current Activity is very handy  Wouldn   t it be nice to have a static getActivity method returning the current Activity with no unnecessary questions   The Activity class is very useful  It gives access to the application   s UI thread  views  resources  and many more  Numerous methods require a Context  but how to get the pointer  Here are some ways    Tracking the application   s state using overridden lifecycle methods  You have to store the current Activity in a static variable and you need access to the code of all Activities  Tracking the application   s state using Instrumentation  Declare Instrumentation in the manifest  implement it and use its methods to track Activity changes  Passing an Activity pointer to methods  and classes used in your Activities  Injecting the pointer using one of the code injection libraries  All of these approaches are rather inconvenient  fortunately  there is a much easier way to get the current Activity  Seems like the system needs access to all Activities without the issues mentioned above  So  most likely there is a way to get Activities using only static calls  I spent a lot of time digging through the Android sources on grepcode com  and I found what I was looking for  There is a class called ActivityThread  This class has access to all Activities and  what   s even better  has a static method for getting the current ActivityThread  There is only one little problem     the Activity list has package access     Easy to solve using reflection   public static Activity getActivity         Class activityThreadClass   Class forName  android app ActivityThread        Object activityThread   activityThreadClass getMethod  currentActivityThread   invoke null       Field activitiesField   activityThreadClass getDeclaredField  mActivities        activitiesField setAccessible true        Map lt Object  Object gt  activities    Map lt Object  Object gt   activitiesField get activityThread       if  activities    null          return null       for  Object activityRecord   activities values              Class activityRecordClass   activityRecord getClass            Field pausedField   activityRecordClass getDeclaredField  paused            pausedField setAccessible true           if   pausedField getBoolean activityRecord                 Field activityField   activityRecordClass getDeclaredField  activity                activityField setAccessible true               Activity activity    Activity  activityField get activityRecord               return activity                       return null      Such a method can be used anywhere in the app and it   s much more convenient than all of the mentioned approaches  Moreover  it seems like it   s not as unsafe as it looks  It doesn   t introduce any new potential leaks or null pointers   The above code snippet lacks exception handling and naively assumes that the first running Activity is the one we   re looking for  You might want to add some additional checks   Blog Post

User · Answer

Personally I did as  Cheok Yan Cheng  said  but I used a  List  to have a  Backstack  of all my activities      If you want to check Which is the Current Activity you just need to get the last activity class in the list    Create an application which extends  Application  and do this   public class MyApplication extends Application implements Application ActivityLifecycleCallbacks  EndSyncReceiver IEndSyncCallback    private List lt Class gt  mActivitiesBackStack  private EndSyncReceiver mReceiver      private Merlin mMerlin      private boolean isMerlinBound      private boolean isReceiverRegistered    Override     public void onCreate             super onCreate                   RealmHelper initInstance            initMyMerlin            bindMerlin            initEndSyncReceiver            mActivitiesBackStack   new ArrayList lt  gt               START Override ActivityLifecycleCallbacks Methods         Override     public void onActivityCreated Activity activity  Bundle bundle            mActivitiesBackStack add activity getClass                 Override     public void onActivityStarted Activity activity            if  isMerlinBound               bindMerlin                      if  isReceiverRegistered               registerEndSyncReceiver                          Override     public void onActivityResumed Activity activity                 Override     public void onActivityPaused Activity activity                 Override     public void onActivityStopped Activity activity            if  AppUtils isAppOnForeground this                if isMerlinBound                    unbindMerlin                              if isReceiverRegistered                   unregisterReceiver mReceiver                             if RealmHelper getInstance      null                   RealmHelper getInstance   close                    RealmHelper getInstance   logRealmInstanceCount  AppInBackground                    RealmHelper setMyInstance null                                       Override     public void onActivitySaveInstanceState Activity activity  Bundle bundle                 Override     public void onActivityDestroyed Activity activity            if mActivitiesBackStack contains activity getClass                  mActivitiesBackStack remove activity getClass                            END Override ActivityLifecycleCallbacks Methods        START Override IEndSyncCallback Methods         Override     public void onEndSync Intent intent            Constants SyncType syncType   null          if intent hasExtra Constants INTENT DATA SYNC TYPE                syncType    Constants SyncType  intent getSerializableExtra Constants INTENT DATA SYNC TYPE                     if syncType    null               checkSyncType syncType                          END IEndSyncCallback Methods     private void checkSyncType Constants SyncType                 if  mActivitiesBackStack contains ActivityClass class              doOperation                In my case I used  Application ActivityLifecycleCallbacks  to    Bind Unbind Merlin Instance  used to get event when the app lose or get connection  for example when you close mobile data or when you open it   It is useful after the  OnConnectivityChanged  intent action was disabled  For more info about MERLIN see  MERLIN INFO LINK Close my last Realm Instance when the application is closed  I will init it inside a BaseActivity wich is extended from all others activities and which has a private RealmHelper Instance   For more info about REALM see  REALM INFO LINK For instance I have a static  RealmHelper  instance inside my  RealmHelper  class which is instantiated inside my application  onCreate   I have a synchronization service in which I create I new  RealmHelper  because Realm is  Thread-Linked  and a Realm Instance can t work inside a different Thread  So in order to follow Realm Documentation  You Need To Close All Opened Realm Instances to avoid System Resources Leaks   to accomplish this thing I used the  Application ActivityLifecycleCallbacks  as you can see up    Finally I have a receiver wich is triggered when I finish to synchronize my application  then when the sync end it will call the  IEndSyncCallback   onEndSync  method in which I look if I have a specific Activity Class inside my ActivitiesBackStack List because I need to update the data on the view if the sync updated them and I could need to do others operations after the app sync    That s all  hope this is helpful  See u

User · Answer

I expand on the top of  gezdy s answer   In every Activities  instead of having to  register  itself with Application with manual coding  we can make use of the following API since level 14  to help us achieve similar purpose with less manual coding   public void registerActivityLifecycleCallbacks  Application ActivityLifecycleCallbacks callback    http   developer android com reference android app Application html registerActivityLifecycleCallbacks 28android app Application ActivityLifecycleCallbacks 29  In Application ActivityLifecycleCallbacks  you can get which Activity is  attached  to or  detached  to this Application   However  this technique is only available since API level 14

User · Answer

getCurrentActivity   is also in ReactContextBaseJavaModule   Since the this question was initially asked  many Android app also has ReactNative component - hybrid app    class ReactContext in ReactNative has the whole set of logic to maintain mCurrentActivity which is returned in getCurrentActivity     Note  I wish getCurrentActivity   is implemented in Android Application class

[android] How to get current foreground activity context in android?

Examples related to android

Examples related to android-activity