Android move data between activities

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http://stackoverflow.com – Example I have 4 activities. A B C D A is a list of objects. B C D are used to add a new object. So A calls B then C then D . However C or D have button to 'add the object' When going up from B or C or D to activity A , A should have a List with these objects. Even if user tap back items should be 'saved' However I dont want to start a new Intent at C or D because i dont want user to go back to A and then click again add new item. I have been adviced to keep these data at application object. Is there any other suggestion ? (HowTos)