Develop Reference

Preventing an App from changing to Portrait Orientation when the Device is unlocked

I'm developing a game that runs in a wrapped webview for Android devices. Everything is working as expected--in this case, I have locked my view to landscape orientation, and prevented the device from restarting the activity if the phone is rotated.
However, if I put my device to sleep and then unlock it, I see my application in portrait mode for a moment, until my device re-orients to landscape. This behavior makes sense, since a phone is naturally used in portrait orientation, but I don't want my activity to switch from landscape.
If I start any other game, by which I mean those presumable written in native code, that is locked into landscape mode, and then lock and unlock my phone, the game doesn't do the same quickly-switch-from-portrait-to-landscape dance.
What am I missing?
In MainActivity I have
this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE)
in several places, including onConfigurationChanged, onWindowFocusChanged, onPause, and onResume.
Here is how my activity is defined in my AndroidManifest
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:hardwareAccelerated="true"
android:screenOrientation="sensorLandscape"
android:configChanges="orientation|screenSize"
android:launchMode="singleTask"
android:alwaysRetainTaskState="true"
android:theme="#android:style/Theme.NoTitleBar.Fullscreen"
android:windowSoftInputMode="stateAlwaysHidden" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Thanks for any help/advise!
-J.L.

You forgot to remove sensor from the screenOrientation tag. Try this:
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:hardwareAccelerated="true"
android:screenOrientation="landscape"
android:configChanges="orientation|screenSize"
android:launchMode="singleTask"
android:alwaysRetainTaskState="true"
android:theme="#android:style/Theme.NoTitleBar.Fullscreen"
android:windowSoftInputMode="stateAlwaysHidden" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

the app still shows as the incorrect orientation for a split second when the phone is unlocked.
Did you move setContentView(R.layout.main) to the onResume, AFTER where you put your orientation code? I would try setting the orientation, then the setContentView()

Android NullPointerException on Screen Orientation Change

I am narrowing down and explaining as simple as can,
main activity initiates an async task.
When orientation change onCreate() is recalled so Async is created once gain. so in onPreExecute() i lock my orientation and in onPostExecute() i release lock on orientation. By this way if Async task has started another instance of task will never get created.
another issue has started, in main activity itself findViewById() returns null when i randomly keep changing the screen orientation. Re-producing once in 5-6 tries.
how to go on this? any help
Does onCreate() get re-called after completion of method or main thread... or is it instantaneous as soon as orientation get changed
Thank you
---------------updated
<application
android:allowBackup="true"
android:icon="#drawable/ap_logo"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="agilepoint.android.mobilebpm.main.LoginActivity"
android:configChanges="orientation"
android:label="#string/app_name"
android:logo="#drawable/menu_button"
android:windowSoftInputMode="adjustPan|stateHidden"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<intent-filter>
<action android:name="android.intent.action.VIEW" />
<data android:scheme="http" />
</intent-filter>
</activity>
</application>

Found my solution...
android:configChanges="orientation" does not work with fragments
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".

Add android:configChanges="orientation" for that perticular activity in manifest.

Android: Activity restarted when turn off wifi in setting

I have added android:configChanges in Manifest, when I change font size or turn off Wifi, the activity will be restarted automatically. Is there any way I can prevent this restarts ?
Thanks for the help.
<activity android:name="com.example.MainActivity" android:theme="#style/SkoletubeTheme"
android:configChanges="mcc|mnc|locale|touchscreen|keyboard|keyboardHidden|navigation|screenLayout|fontScale|uiMode|orientation|screenSize|smallestScreenSize"
android:launchMode="singleTask"
android:screenOrientation="portrait" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

You have already caught the exception. It's happen for android:configChanges . Please remove unnecessary values from android:configChanges. Only keeps orientation .
I think your problem will be solved. Try this and let me know if it's acceptable or not.

How to avoid force close on mobile phone orientation change?

my android application crashes and shows force close when i tilt the mobile phone. is there any suggestions that i can remove such problem? By the way i am developing a LBS application which uses the google maps (MapView).
I have a splash screen and then shown a ListActivity as below :
<activity android:name=".Splash" android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Home" android:label="#string/app_name" android:configChanges="orientation" android:windowSoftInputMode="stateHidden">
<intent-filter>
<action android:name="com.nepways.HOME" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
what is wrong with my declaration, the splash screen loads and list activity is also whown correctly but when i change the orientation the application is closed. Please help me.

When you change your orientation the activity is restarted
look at the logcat to see what exception causes your application to FC
You can change your manifest to disable activity restarting by customizing configChanges, if you stil have the problem override onConfigurationChanged() to fix what is generating this exception (like initialize something that may cause a nullpointer)

First of all as it is said the app is restarting (or as it is said in reference redrawing) each time when you change orientation.
To block it in your manifest file in activity you have to put this line which describes the activity orientation:
<activity android:name=".Splash"
android:label="#string/app_name"
android:screenOrientation="portrait">...
And about this buttons, or keymaps. Telling the truth Ive got thise warnings sometimes but it doesnt change anything in my app. So first change the orientation settings and then it should work correct.
If you want use other screen orientation remember to check here:
http://developer.android.com/guide/topics/manifest/activity-element.html

If you want to avoid restarting your activity on orientation change, you can put this in the activity in the manifest file:
android:configChanges="orientation"
Otherwise, we will need to see more code, and a stacktrace.

Does using one attribute of configChanges calls onConfigurationChanged() anyway?

If I use this code in my Manifest file:
<activity android:name=".MyAct"
android:label="#string/app_name"
android:configChanges="orientation|keyboardHidden"> //<-SEE THIS
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
As you can see I am declaring that the activity shall not be restarted when the screen rotation and keyboard visibility have been changed.
However, does this mean that the method onConfigurationChanged() will be called ONLY in case of these two events (in other cases the activity shall restart)?
Or it means that the activity does not restart even if only one attribute has been used?
I haven't been able to find this answer in the documentation.

Correct. It means that the activity does not restart even if only one attribute has been used. The onConfigurationChanged() method will be envoked if one of the attribute occur, i.e for those which are not specified, the activity will restart when they occur.