I have working and analysing sample hello_ar_java project in android.I want to place a 3d object in a center position of the camera in android.i'm expecting answers android only and i dont want unity answes because i don't know unity.
The point the camera starts is THE origin. So, just place your object at the origin, and everything should be fine. If you want the object to move with the camera, you should have the camera's transform as the parent of your object's transform.