When is ondestroy called

These are more of quick notes for my quick reference, a cheat-sheet of sorts when I have to make choices. And I guess this can come handy to you too in your wise decision making. Just automate the deployment infrastructure for every tenant for quick set-up. Most expensive of all the models from infrastructure cost stand-point.

Relatively longer deployment t. OnApplicationFocus to save any data. Is something described here not working as you expect it to? It might be a Known Issue.

Please check with the Issue Tracker at issuetracker. Version: Language English. Scripting API. Suggest a change. If you have critical code that must be run each time app finishes you need to run it in onPause. When the application gets force stop, Process.

Go through this link. You will get some idea. Android force Stop callback to application? I am assuming you have code that you want to execute in onDestroy referring to your line:.

For more information about suitable operations to perform during onStop , see onStop. For more information about saving data, see Saving and restoring activity state. Completion of the onPause method does not mean that the activity leaves the Paused state. Rather, the activity remains in this state until either the activity resumes or becomes completely invisible to the user. If the activity resumes, the system once again invokes the onResume callback. If the activity returns from the Paused state to the Resumed state, the system keeps the Activity instance resident in memory, recalling that instance when the system invokes onResume.

If the activity becomes completely invisible, the system calls onStop. The next section discusses the onStop callback. When your activity is no longer visible to the user, it has entered the Stopped state, and the system invokes the onStop callback. This may occur, for example, when a newly launched activity covers the entire screen. The system may also call onStop when the activity has finished running, and is about to be terminated.

This is where the lifecycle components can stop any functionality that does not need to run while the component is not visible on the screen. In the onStop method, the app should release or adjust resources that are not needed while the app is not visible to the user. For example, your app might pause animations or switch from fine-grained to coarse-grained location updates. Using onStop instead of onPause ensures that UI-related work continues, even when the user is viewing your activity in multi-window mode.

You should also use onStop to perform relatively CPU-intensive shutdown operations. For example, if you can't find a more opportune time to save information to a database, you might do so during onStop. The following example shows an implementation of onStop that saves the contents of a draft note to persistent storage:. Note, the code sample above uses SQLite directly.

You should instead use Room, a persistence library that provides an abstraction layer over SQLite. To learn more about the benefits of using Room, and how to implement Room in your app, see the Room Persistence Library guide. When your activity enters the Stopped state, the Activity object is kept resident in memory: It maintains all state and member information, but is not attached to the window manager.

When the activity resumes, the activity recalls this information. The system also keeps track of the current state for each View object in the layout, so if the user entered text into an EditText widget, that content is retained so you don't need to save and restore it. Note: Once your activity is stopped, the system might destroy the process that contains the activity if the system needs to recover memory. Even if the system destroys the process while the activity is stopped, the system still retains the state of the View objects such as text in an EditText widget in a Bundle a blob of key-value pairs and restores them if the user navigates back to the activity.

For more information about restoring an activity to which a user returns, see Saving and restoring activity state. From the Stopped state, the activity either comes back to interact with the user, or the activity is finished running and goes away. If the activity comes back, the system invokes onRestart. If the Activity is finished running, the system calls onDestroy.

The next section explains the onDestroy callback. This is where the lifecycle components can clean up anything it needs to before the Activity is destroyed. Instead of putting logic in your Activity to determine why it is being destroyed you should use a ViewModel object to contain the relevant view data for your Activity.

If the Activity is going to be recreated due to a configuration change the ViewModel does not have to do anything since it will be preserved and given to the next Activity instance. If the Activity is not going to be recreated then the ViewModel will have the onCleared method called where it can clean up any data it needs to before being destroyed.

You can distinguish between these two scenarios with the isFinishing method. If the activity is finishing, onDestroy is the final lifecycle callback the activity receives.

If onDestroy is called as the result of a configuration change, the system immediately creates a new activity instance and then calls onCreate on that new instance in the new configuration. The onDestroy callback should release all resources that have not yet been released by earlier callbacks such as onStop. The system kills processes when it needs to free up RAM; the likelihood of the system killing a given process depends on the state of the process at the time.

Process state, in turn, depends on the state of the activity running in the process. The system never kills an activity directly to free up memory. Instead, it kills the process in which the activity runs, destroying not only the activity but everything else running in the process, as well. To learn how to preserve and restore your activity's UI state when system-initiated process death occurs, see Saving and restoring activity state.

A user can also kill a process by using the Application Manager under Settings to kill the corresponding app. For more information about processes in general, see Processes and Threads. For more information about how the lifecycle of a process is tied to the states of the activities in it, see the Process Lifecycle section of that page. However, the system destroys the activity by default when such a configuration change occurs, wiping away any UI state stored in the activity instance.

Similarly, a user expects UI state to remain the same if they temporarily switch away from your app to a different app and then come back to your app later.

To learn more about user expectations versus system behavior, and how to best preserve complex UI state data across system-initiated activity and process death, see Saving UI State. This section outlines what instance state is and how to implement the onSaveInstance method, which is a callback on the activity itself.

If your UI data is simple and lightweight, such as a primitive data type or a simple object like String , you can use onSaveInstanceState alone to persist the UI state across both configuration changes and system-initiated process death.

There are a few scenarios in which your activity is destroyed due to normal app behavior, such as when the user presses the Back button or your activity signals its own destruction by calling the finish method. When your activity is destroyed because the user presses Back or the activity finishes itself, both the system's and the user's concept of that Activity instance is gone forever.

In these scenarios, the user's expectation matches the system's behavior and you do not have any extra work to do. However, if the system destroys the activity due to system constraints such as a configuration change or memory pressure , then although the actual Activity instance is gone, the system remembers that it existed. If the user attempts to navigate back to the activity, the system creates a new instance of that activity using a set of saved data that describes the state of the activity when it was destroyed.

The saved data that the system uses to restore the previous state is called the instance state and is a collection of key-value pairs stored in a Bundle object. By default, the system uses the Bundle instance state to save information about each View object in your activity layout such as the text value entered into an EditText widget.

So, if your activity instance is destroyed and recreated, the state of the layout is restored to its previous state with no code required by you. However, your activity might have more state information that you'd like to restore, such as member variables that track the user's progress in the activity.

Note: In order for the Android system to restore the state of the views in your activity, each view must have a unique ID, supplied by the android:id attribute. A Bundle object isn't appropriate for preserving more than a trivial amount of data because it requires serialization on the main thread and consumes system-process memory. To preserve more than a very small amount of data, you should take a combined approach to preserving data, using persistent local storage, the onSaveInstanceState method, and the ViewModel class, as outlined in Saving UI States.

As your activity begins to stop, the system calls the onSaveInstanceState method so your activity can save state information to an instance state bundle.

The default implementation of this method saves transient information about the state of the activity's view hierarchy, such as the text in an EditText widget or the scroll position of a ListView widget. To save additional instance state information for your activity, you must override onSaveInstanceState and add key-value pairs to the Bundle object that is saved in the event that your activity is destroyed unexpectedly.

If you override onSaveInstanceState , you must call the superclass implementation if you want the default implementation to save the state of the view hierarchy.

Note: onSaveInstanceState is not called when the user explicitly closes the activity or in other cases when finish is called. To save persistent data, such as user preferences or data for a database, you should take appropriate opportunities when your activity is in the foreground. If no such opportunity arises, you should save such data during the onStop method. When your activity is recreated after it was previously destroyed, you can recover your saved instance state from the Bundle that the system passes to your activity.

Both the onCreate and onRestoreInstanceState callback methods receive the same Bundle that contains the instance state information. Because the onCreate method is called whether the system is creating a new instance of your activity or recreating a previous one, you must check whether the state Bundle is null before you attempt to read it.

If it is null, then the system is creating a new instance of the activity, instead of restoring a previous one that was destroyed. For example, the following code snippet shows how you can restore some state data in onCreate :. Instead of restoring the state during onCreate you may choose to implement onRestoreInstanceState , which the system calls after the onStart method.

The system calls onRestoreInstanceState only if there is a saved state to restore, so you do not need to check whether the Bundle is null:. Caution: Always call the superclass implementation of onRestoreInstanceState so the default implementation can restore the state of the view hierarchy.

This section covers topics you need to know to implement successful activity transitions. These topics include starting an activity from another activity, saving activity state, and restoring activity state. An activity often needs to start another activity at some point. This need arises, for instance, when an app needs to move from the current screen to a new one. In either case, you pass in an Intent object. The Intent object specifies either the exact activity you want to start or describes the type of action you want to perform and the system selects the appropriate activity for you, which can even be from a different application.

An Intent object can also carry small amounts of data to be used by the activity that is started. For more information about the Intent class, see Intents and Intent Filters.

If the newly started activity does not need to return a result, the current activity can start it by calling the startActivity method.

When working within your own application, you often need to simply launch a known activity. For example, the following code snippet shows how to launch an activity called SignInActivity.

Your application might also want to perform some action, such as send an email, text message, or status update, using data from your activity. In this case, your application might not have its own activities to perform such actions, so you can instead leverage the activities provided by other applications on the device, which can perform the actions for you.