How to avoid black screen in android while my app is loading?

Optimize ur code,try to reduce code from onCreate(),this was issue faced by me i solved it by reducing code in onCreate().

Best of Luck

Add below line in your android style.xml file in style tag .

 <item name="android:windowDisablePreview">true</item>

Complete code :

 <style name="AppBaseTheme" parent="android:Theme.Light.NoTitleBar">
    <!--
        Theme customizations available in newer API levels can go in
        res/values-vXX/styles.xml, while customizations related to
        backward-compatibility can go here.
    -->
    <item name="android:windowDisablePreview">true</item>
</style>

Since you have cleared out your onCreate() and assigned your initialization tasks to a worker thread, the fact that your screen nonetheless remains dark for a while after your app is launched is probably due to the complexity of the graphics in your initial display (rather than to your initialization code, which is probably model-related, rather than view-related).

The solution that you say worked for you is to use a visible background as your theme. I'm glad that you found that to be adequate, but for some purposes a more specific (e.g., logo / app name) splash screen (which displays quickly because it uses much simpler graphics) would be more desirable.

Please see the answer linked below for a detailed description (with sample code) of how a splash screen that displays quickly can be implemented:

Create a true splash screen

This also discusses the approach that you have accepted above.

i'm not sure.

but, Try this in Manifest inside your activity

android:theme="@android:style/Theme.Translucent" 

Or

android:theme="@android:style/Theme.Light"

I have seen a good solution about splash screen... hope it useful

https://stackoverflow.com/a/8654361/762919