emulator of android studio what i can should do

Question

when put textview in center .after run emulator the textview become on top

Answer 1

Then you probably have set the dimensions/aspect ratio of the emulator to be different from the "design" tab's. You should learn how to handle different dimentions/aspect ratios.
Other than that, I suppose you have some extra fields in the XML that are causing the unneeded behaviour?