How to save/restore Activity's and Fragment's state | shopbaocaosugai.com

Android on restore instance state example. Saving and restoring the Activity State

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An example would be when the user changes the orientation of the device. I would recommend marking this answer as the "Accepted" one to better help future readers. Note that there is no onRestoreInstanceState method inside Fragment.

Lifecycle callbacks

It is a new activity. When is onRestoreInstanceState called?

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Default Saving of User Interface State In the previous chapter, the diagnostic output from the StateChange example application showed that an activity goes through a number of state changes when the device on which it is running is rotated sufficiently to trigger an orientation change. Once onRestoreInstanceState is called.

Log; import android.

Understand the Activity Lifecycle | Android Developers

In the testing I did on the Android Virtual Device and two actually devices, it did get called between onPause and onStopbut the quote below suggests one should not take this for granted. The activity is then rebuilt using this saved state.

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Fragment is still there, just like those member variables inside. And of course, after this pause, the user will want to return to the previous application state before pause. Nonetheless, this method is called by Android between the onPause and onStop methods.

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Unless you avail yourself to certain state saving mechanisms, any data your activity has at the time of orientation change android on restore instance state example be completely lost in this seemingly simple act.

It means that every single member variables are also destroyed.

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Actually I also feel weird with my codes myself already EditText : package com. The Bundle cover letter for graduate program examples also contains a set of methods that can be used to get and set key-value pairs for a variety of data types including both primitive types including Boolean, char, double and float values and objects such as Strings and CharSequences. Use getPreferences for preferences which are restricted to the calling activity.

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Is there any more information you could provide about it? In other instances, this typically consists of extracting values and settings within the onSaveInstanceState method and saving the data as key-value pairs within the Bundle object passed through to the activity by the runtime system.

Switching the device from portrait to landscape causes Android to stop and restart the Activity, allowing Activities the opportunity to redraw a screen for the different dimensions.

Before your app is suspended, the onSaveInstanceState method of your Activity will be fired, followed by onPause. In order to extract the text entered into the EditText component we need to gain access to that user interface object.

  • Saving and Restoring Activity State in Android Studio - Techotopia
  • If it is null, then the system is creating a new instance of the activity, instead of restoring a previous one that was destroyed.

When is onCreate called? Therefor, myObject will be null in this situation when the orientation rotates more than once.

The Activity class provides the first, and possibly easiest, means of saving and restoring activity state. This method is called when an Activity is being backgrounded either after onPause or onStopdepending on different factors.

In loose terms, a Bundle is a custom Android hash map. These methods only work if the Views with data can be identified, supplied by the android:id attribute. To achieve that in Android, you must be aware about Activity lifecycle.

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A wide range of classes already implements the Parcelable interface. I hope that you have found this tutorial helpful.

If it is null, then the system is creating a new instance of the activity, instead of restoring a previous one that was destroyed. Therefor, myObject will be null in this situation when the orientation rotates more than once.

The current activity is destroyed and restarted. The method to use will depend on the nature of the activity.

Saving and Restoring Activity State in Android Studio