I'm working on an application which have 5 activities and any of the activity can access other 4. In one of the activities i have a `Finish` button that should put my application on background thread. I want to notify my other activities to call `finish()`, and for that i have two ideas in mind. One is by using `intent` but other is using `interface` but i'm little confused to decide on which way should i go? 

Are there any other way to notify all activities on same application from an event of one activity?

Thanks