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Let's say I have a list of homogenous items which is likely to be changed in the lifetime of my Activity by user interaction or OS events. The Activity contains a FragmentPager which shows a number of ListFragment s. These fragments share the previously mentioned data but display it in different ways. E.g. they differ in sorting order or display only a subset of the data. Currently each fragment keeps a separate list containing the respective part of the data in the respective order. When the data changes, basicly every fragment has to be updated. This means resorting or adding/removing items from some of the fragments. What is the best practice to keep the data in the different fragments consistent? Currently I have some sort of an observer object, which is notified when something changes and subsequently notifies the connected fragments. But there are a couple of problems: When the app just started, some of the fragments haven't been created by the FragmentPager