[Android] Call getResource() after onCreate()

Error Message

12-13 14:49:27.316: E/AndroidRuntime(881): Caused by: java.lang.NullPointerException
12-13 14:49:27.316: E/AndroidRuntime(881): at android.content.ContextWrapper.getResources(ContextWrapper.java:81)

Occurred when
call getResources out of onCreate


Solution

Must using getResource() after onCreate()

...but why?