How to Save State During Orientation Change in Android If the State Is Made of My Classes

How to save state during orientation change in Android if the state is made of my classes?

EDIT: On newer versions of Android and with the compatibility library, retained fragments are usually the best way to handle keeping expensive-to-recreate data alive across activity destruction/creation. And as Dianne pointed out, retaining nonconfiguration data was for optimizing things like thumbnail generation that are nice to save for performance reasons but not critical to your activity functioning if they need to be redone - it's not a substitute for properly saving and restoring activity state.

But back when I first answered this in 2010:

If you want to retain your own (non view-state) data, you can actually pass an arbitrary object specifically for orientation changes using onRetainNonConfigurationInstance(). See this Android Developers blog post. Just be careful not to put any Views or other references to the pre-rotation Context/Activity in the object you pass, or you'll prevent those objects from being garbage collected and may eventually run out of memory (this is called a context leak).

Android save state on orientation change

Have you tried using: its work through

<activity name= ".YourActivity" android:configChanges="orientation|screenSize"/>

in Manifest file?

It does not work by default because , when you change the orientation onCreate will be called again and it redraws your view.

If you write this parameter no need to handle in Activity , the framework will take care of rest of things.
It will retain the state of the screen or layout if orientation is changed.

NOTE If you are using a different layout for landscape mode , by adding these parameters the layout for landscape mode will not be called.

Other way and Another way

Save state of activity when orientation changes android

I use in KOTLIN static var / val :

class MyFragment : Fragment()
{
     //all my code
     //access to static vars -> MyStaticClass.hello
}

class MyStaticClass 
{
    companion object {
        var hello: String = "Static text"
        var number_static: Int = 0
    }
}

Android : Save application state on screen orientation change

Well if you have the same layout for both screens then there is no need to do so just add below line in your manifest in Activity node

android:configChanges="keyboardHidden|orientation"

for Android 3.2 (API level 13) and newer:

android:configChanges="keyboardHidden|orientation|screenSize"

because the "screen size" also changes when the device switches between portrait and landscape orientation. Documentation here: http://developer.android.com/guide/topics/manifest/activity-element.html

Save data and change orientation

If you have small data, you can save and restore it using onSavedInstanceState and onRestoreInstanceState .. for details go through this link Saving data

But in case, you have large data then I must say, you should not allow for the orientation changes(which force your activity to recreate). You can restrict it by adding below line in manifest file :

android:configChanges="orientation|keyboardHidden" // fixes orientation

Save the Tab state during orientation change

That's not the best way. You should use onRetainNonConfigurationInstance() and getLastNonConfigurationInstance() to retain the state between config changes. Those methods are specifically for saving state during config changes.

public Object onRetainNonConfigurationInstance() {
    return mTabHost.getCurrentTab();
}

public void onCreate() {
   ...
   Integer lastTab = (Integer) getLastNonConfigurationInstance();
   if(lastTab != null) {
      mTabHost.setCurrentTab(lastTab);
   }
   ...
}

What's the right way to save instance state only on rotation?

Turns out my question was wrong from the beginning.

When the device rotates, Android calls onSaveInstanceState(Bundle outState) and onRestoreInstanceState(Bundle savedInstanceState) as a way for the developer to save/restore state. When the activity is destroyed via back button or finish(), onSaveInstanceState is not called and the savedInstanceState bundle that's passed to onCreate() is null. So trying to answer the "was this created after a rotation or not?" question is irrelevant.

Posted in case someone has the same question and thanks to all that took time to read and help.

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