Develop Reference

How get rig of the starting non-seen activity?

I have an app where I used the dark theme. I have also added a splash screen where I have added an animation. The background of the SplashActivity is white. When I first start the app, I get a dark screen and then the splash screen is displayed. How to get rid of that dark screen and see directly the splash screen? Thanks

Its related to Cold Start. It happens when your app starts for the first time as explained in the android documentation. However to deal with it I prefer the solution of having background drawable and set it to app theme if your Splash screen is static but in your case as you are using animations you need to use mixture of both techniques i.e. setting the splash screen theme as drawable which is loaded during cold start and later on when it finishes you render your animated stuff.

AnimatedVectorDrawable as Window background. Is it possible?

I'm trying to use AnimatedVectorDrawable as a splash animation placed in the window background. I use the official example given in https://developer.android.com/reference/android/graphics/drawable/AnimatedVectorDrawable.html. It appears but doesn't animate.
Are animations in a Window background possible at all?

The first screen that you see when opening an app for the first time (cold start) is a screen placeholder create by the WindowManager. It creates the placeholder by getting resources that you set on your theme, like the window background and status bar color. To start the animation of your window background you have to call its start() method, but the WindowManager is a system service that you have little or no control over. So on this phase of application initialisation, unless there is some obscure way to control the WindowManager in the Application.onCreate() method, it is not possible to animate the vector background.
I opened from cold start a lot of my apps including Google ones and not a single one seems to implement animations on the cold start phase (like the docs of Material Design imply possible). A very few make animations after the cold start at the onCreate of the main activity.
If it's not a problem start the animation after he cold start, like in the case of moving the logo to the top of the screen, you can:
Set a theme with attribute android:windowBackground to your static drawable at your launch activity in AndroidManifest.xml
Before call super.onCreate() in your Activity, change the theme for your default theme.
Set a content view with a ImageView of your AnimatedVectorDrawable at the same position of your static window background vector.
Call start() method of your AnimatedVectorDrawable.
Here is an AndroidDeveloper's post explaining in details how to deal with application themes for launch screens

setTheme works but only after loading theme from manifest

I'm trying to set the theme of my Activity during runtime, choosing one of a number of themes. I want the chosen theme to display immediately on startup of the Activity.
In the <application> part of my manifest I have set a default theme with android:theme="#style/AppTheme". And then in my onCreate() I use setTheme(R.style.DarkAppTheme) to set the theme to a user-selected theme (replacing DarkAppTheme with the selected theme).
And based on research it seems that setTheme() should go before onCreate() and before setContentView(), which I do.
BUT although this works to display the Activity in the user selected theme, the Activity first loads with what looks like the default theme, and then after a short delay the correct theme loads.
If I set the user selected theme directly in the manifest, that loads immediately as I want, but of course that is hardcoded and I want to change this dynamically based on a shared preference.
How do I avoid the visible changeover? I want the user selected theme to be displayed right from the start.
Thanks.

The Activity first loads with what looks like the default theme, and then after a short delay the correct theme loads... How do I avoid the visible changeover?
There are 2 parts to an Activity 'Enter/Opening' window animation, when your app is first launched from the icon on the Home Screen:
The 'dark gray rectangle appear' animation. This is the initial blank screen that the system process draws when launching the app (source). It's also known as the "theme preview" screen or "splash screen". It can be white if your app uses a Light theme.
The 'fade in (or circular reveal) of the view layout'. This is the animation of your view layout appearing on top of the dark gray rectangle. It happens after part 1.
Part 1 is what you identified as "what looks like the default theme". You can disable this first part with the following item in your Activity/App style:
<item name="android:windowDisablePreview">true</item>
This will prevent the 'dark gray rectangle appear' animation, and only allow the 'reveal of the view layout', to therefore avoid the visible changeover or flicker. But there are caveats:
You have to ensure that your Activity launches quickly, because there will be no visual animation feedback for the user until your layout is fully loaded. That's why the theme preview is normally on by default.
It causes strange bugs on context menus: For any PopupWindow, the 'Enter' animation will no longer happen, and it will just display instantly ('Exit' animations are not affected). This also applies to system PopupWindows like the overflow menu list, and the drop-down list of an AutoCompleteTextView. This bug happens on Android 4/5/6, but not on Android 7/8. More info here.
Documentation of windowDisablePreview:
Flag allowing you to disable the splash screen for a window. The default value is false; if set to true, the system can never use the window's theme to show a splash screen preview before your actual instance is shown to the user.
Further info:
How to set a theme to whole application in code, but not in the Manifest?
Android - Disable dummy starting window of application

The theme on AndroidManifest just appears if your Activity take too long to load. You can try to tunning up Activity load and remove android:theme="#style/AppTheme" from AndroidManifest or even set a compromise between these two use.
I hope it helps you \o/

Flash of activity with dark background while created

I have an activity with bark background launched as singleInstanse, and when it's starts the first time it has a shot white flash (white background shown) before showing its content. How can I prevent that? Or may be it is possible set up activity's default background color at start? Thanks.

This is due to what is called the preview window during app launching.
A very clear explanation of the issue and how to get around it is given by Cyril Mottier in android-app-launching-made-gorgeous

your app theme should have background color... thid color will replace the dark screen.

Activity recreation due to Theme.Translucent

I have an application with one parent and some child activities. Requirement is to play some custom animation on child activity launch. For smooth animation and avoid delay between switching I applied Theme.Translucent on application in the Manifest. Animation is running properly and application behavior is proper until I turn developer setting ON to keep single activity.
Application stuck at the parent activity due to infinite recreation (onCreate() followed by onStart(), onResume(), onDestroy and so on) when there.
1) Developer setting is ON to keep single activity.
2) My application goes in the background with child activity is on the top.
3) My activity comes to the foreground.
I am facing this issue only on Android 4.0 series but found in the documentation that Theme Translucent is for API Level 10 and below.
I think activity recreation issue is due to translucency of child activity that is on the top and parent is below. As child activity is translucent, its require parent activity in the background. App creating parent in background and its being destroyed due to developer setting is ON.
I tried to find Translucent equal for API level above 10 but no luck. Is there any API to Translucent activities with API level above 10 or any other way to avoid flickering/delay between activity switching.
Thanks

If you want your activity to have a translucent window, you can add:
<item name="android:windowIsTranslucent">true</item>
To your AppTheme in res/values/styles.xml.