Android :: Get User Defined Environment Variables?

I would like to use self defined Environment variables in my source code.

I use System.getenv() to do this and the code line looks like this. Log.d("MyTest","== MyEnv " + System.getenv("AP") + " ANDROID_ASSETS:" + System.getenv("ANDROID_ASSETS"));

Before I execute my code I define my AP variable with export: export AP="12345" and the this is my output of set command

ANDROID_ASSETS=/system/app
ANDROID_BOOTLOGO=1
ANDROID_DATA=/data
ANDROID_PROPERTY_WORKSPACE=9,32768
ANDROID_ROOT=/system
AP=12345

Then I execute my code and I get this line from logcat

D/MyTest( 5363): == MyEnv null ANDROID_ASSETS:/system/app

The value for my defined Environment variable is null. Any suggestions on why it didn't work?