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Activity restart on rotation Android

In my Android application, when I rotate the device (slide out the keyboard) then my Activity is restarted (onCreate is called). Now, this is probably how it's supposed to be, but I do a lot of initial setting up in the onCreate method, so I need either:

  1. Put all the initial setting up in another function so it's not all lost on device rotation or
  2. Make it so onCreate is not called again and the layout just adjusts or
  3. Limit the app to just portrait so that onCreate is not called.
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Isaac Waller Avatar asked Jan 19 '09 00:01

Isaac Waller


People also ask

How do I stop Android from restarting activity when changing orientations?

If you want the activity to not restart during screen orientation change, you can use the below AndroidManifest. xml. Please note the activity android:configChanges=”orientation|screenSize” attribute. This attribute makes the activity not restart when change screen orientation.

What happens to activity when device is rotated?

So instead of destroying and recreating your Activity, Android will just rotate the screen and call one of the lifecycle methods: onConfigurationChanged. If you have a Fragment attached to this Activity, it will also receive a call to its onConfigurationChanged method.

How do you handle rotation on Android?

If you want to manually handle orientation changes in your app you must declare the "orientation" , "screenSize" , and "screenLayout" values in the android:configChanges attributes. You can declare multiple configuration values in the attribute by separating them with a pipe | character.


2 Answers

Update for Android 3.2 and higher:

Caution: Beginning with Android 3.2 (API level 13), the "screen size" also changes when the device switches between portrait and landscape orientation. Thus, if you want to prevent runtime restarts due to orientation change when developing for API level 13 or higher (as declared by the minSdkVersion and targetSdkVersion attributes), you must include the "screenSize" value in addition to the "orientation" value. That is, you must declare android:configChanges="orientation|screenSize". However, if your application targets API level 12 or lower, then your activity always handles this configuration change itself (this configuration change does not restart your activity, even when running on an Android 3.2 or higher device).

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Gorm Avatar answered Oct 14 '22 15:10

Gorm


Using the Application Class

Depending on what you're doing in your initialization you could consider creating a new class that extends Application and moving your initialization code into an overridden onCreate method within that class.

public class MyApplicationClass extends Application {   @Override   public void onCreate() {     super.onCreate();     // TODO Put your application initialization code here.   } } 

The onCreate in the application class is only called when the entire application is created, so the Activity restarts on orientation or keyboard visibility changes won't trigger it.

It's good practice to expose the instance of this class as a singleton and exposing the application variables you're initializing using getters and setters.

NOTE: You'll need to specify the name of your new Application class in the manifest for it to be registered and used:

<application     android:name="com.you.yourapp.MyApplicationClass" 

Reacting to Configuration Changes [UPDATE: this is deprecated since API 13; see the recommended alternative]

As a further alternative, you can have your application listen for events that would cause a restart – like orientation and keyboard visibility changes – and handle them within your Activity.

Start by adding the android:configChanges node to your Activity's manifest node

 <activity android:name=".MyActivity"       android:configChanges="orientation|keyboardHidden"       android:label="@string/app_name"> 

or for Android 3.2 (API level 13) and newer:

<activity android:name=".MyActivity"       android:configChanges="keyboardHidden|orientation|screenSize"       android:label="@string/app_name"> 

Then within the Activity override the onConfigurationChanged method and call setContentView to force the GUI layout to be re-done in the new orientation.

@Override public void onConfigurationChanged(Configuration newConfig) {   super.onConfigurationChanged(newConfig);   setContentView(R.layout.myLayout); } 
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Reto Meier Avatar answered Oct 14 '22 13:10

Reto Meier