What is use of onSaveInstanceState in Android?

How do I use onSaveInstanceState on Android?

onSaveInstanceState method gets called typically before/after onStop() is called. This varies from Android version to version. In the older versions it used to get before onStop() . Inside this method, we save the important values in the Bundle in the form of key value pairs.

How do I use onSaveInstanceState and onRestoreInstanceState on Android?

The onSaveInstanceState() method allows you to add key/value pairs to the outState of the app. Then the onRestoreInstanceState() method will allow you to retrieve the value and set it back to the variable from which it was originally collected.

What is the difference between the onPause () event and the onSaveInstanceState () event?

Instead, you should use onPause() to store persistent data (such as data that should be saved to a database) when the user leaves the activity. onSaveInstanceState() is meant to “remember” the current state when a configuration change occurs like e.g. a screen orientation change.

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When in the activity lifecycle is onSaveInstanceState () called?

onSaveInstanceState() calls between onPause() and onStop(). This method mainly used to keep the state in orientation change. when you rotate the screen activity will destroy and create again. So the data you attached in runtime will be lost.

What is bundle class in Android?

Android Bundle is used to pass data between activities. The values that are to be passed are mapped to String keys which are later used in the next activity to retrieve the values. Following are the major types that are passed/retrieved to/from a Bundle.

What is headless fragment?

Headless fragment is nothing but a fragment which does not have a view. In onCreate() of the fragment lifeCycle, use setRetainInstance(true); . This will not destroy the fragment even if the activity recreates. So if an AsyncTask is running in fragment, on recreation of the activity, you wont lose the AsyncTask.

What is the use of onCreate method in Android?

onCreate(savedInstanceState); calls the method in the superclass and saved InstanceState of the activity if any thing damage the activity so its saved in instanceState so when reload the activity it will be the same before.

What are Android activities?

An Android activity is one screen of the Android app’s user interface. In that way an Android activity is very similar to windows in a desktop application. An Android app may contain one or more activities, meaning one or more screens.

What is Android application life cycle?

The Three Lives of Android

The Entire Lifetime: the period between the first call to onCreate() to a single final call to onDestroy(). We may think of this as the time between setting up the initial global state for the app in onCreate() and the release of all resources associated with the app in onDestroy().

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When onPause method is called in Android?

onPause. Called when the Activity is still partially visible, but the user is probably navigating away from your Activity entirely (in which case onStop will be called next). For example, when the user taps the Home button, the system calls onPause and onStop in quick succession on your Activity .

How do I use onStart on Android?


  1. When activity start getting visible to user then onStart() will be called.
  2. This calls just after the onCreate() at first time launch of activity.
  3. When activity launch, first onCreate() method call then onStart() and then onResume().
  4. If the activity is in onPause() condition i.e. not visible to user.

How do you kill an activity?

Launch your application, open some new Activity, do some work. Hit the Home button (application will be in the background, in stopped state). Kill the Application — easiest way is to just click the red “stop” button in Android Studio. Return back to your application (launch from Recent apps).

Is onCreate only called once?

@OnCreate is only for initial creation, and thus should only be called once. If you have any processing you wish to complete multiple times you should put it elsewhere, perhaps in the @OnResume method.

How many times is onCreate called?

OnCreate will only be called one time for each lifetime of the Activity. However, there are a number of situations that can cause your activity to be killed and brought back to life.

Is OnResume called after onCreate?

OnStart. OnStart is always called by the system after OnCreate is finished. Activities may override this method if they need to perform any specific tasks right before an activity becomes visible such as refreshing current values of views within the activity. Android will call OnResume immediately after this method.

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