OnStop() gets called when your activity has stopped being visible to the user. OnStart() gets called when your activity becomes visible to the user. Just as with onCreate() and onDestroy(), your activity inherits them from the Android Activity class. Specifically, there are three key lifecycle methods that deal with when an activity becomes visible or invisible to the user: onStart(), onStop(), and onRestart(). The activity still exists in the background and maintains all state information. In addition to the onCreate() and onDestroy() methods, which deal with the overall lifecycle of the activity, there are other lifecycle methods that deal with an activity’s visibility.Īn activity has a state of stopped if it’s completely hidden by another activity and isn’t visible to the user. That’s really useful, because it allows the Android OS to stay in touch with the state of an activity.įortunately, it’s easy to handle actions that relate to an activity’s visibility if you use the right lifecycle methods. Bundles can be sent between processes, for example. A Bundle has additional abilities compared to a Map. You would want that variable to be recalculated the next time onCreate() is called.Ī: No, but it’s designed to work like a. For example, you might have a variable that stores the current screen width. Q: Why doesn’t Android automatically store every instance variable automatically? Why do I have to write all of that code myself?Ī: You might not want every instance variable stored. Also, if the user changed their locale, you might want to recreate the UI in the local language. If your code in onCreate() depended upon the screen configuration (for example, if you had different layouts for landscape and portrait), then you would want onCreate() to be called every time the configuration changed. Q: Why does Android want to recreate an activity just because I rotated the screen?Ī: The onCreate() method is normally used to set up the screen.
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