can you explain why does not allow network access in the main thread of a process in Android?
If anybody can explain. Its will be helpful for me.
Because the main thread is responsible for all the UI (user interface) operations (it is also called the UI thread). Everything related to displaying stuff in the screen is done by it. So if you occupy the main thread with long operations such as a network operation, you will experience jitter in the screen and even ANR errors (Application Not Responding). In more recent versions of Android you will not even be allowed to do that as the application throws NetworkOnMainThreadException.