android - Stop asynctask from other activity -

i creating app using asynctask download file server. has several activities. start 1 asynctask activity , want stop activity b. how can archieve ???

it possible call previous activity's public methods using typecasting of getparentactivity() method on activity b :

((previousactivity)getparentactivity()).somepublicmethod(); 

this works if opened activity b activity a. if want able call method activities, try creating static class , save instance of activity a. way, wherever on app, method can called. wary of null values when doing this.

this sample of static class.

public static class constants{    public static activitya activityainstance; } 

when open activitya (oncreate method) save it's instance:

constants.activityainstance = activitya.this; 

this part saves instance of activitya static class. whereever on app, can access instance , call it's public methods:

e.g. app on activityz have import static class , call activitya instance:

constants.activityainstance.somepublicmethodtostoptheasynctask();