Difference between android runOnUiThread and simple code in java

Question

I am a beginner in android application development.I am working with threads in android.I have read about a runOnUiThread which run code on main UI(if i am not wron

Answer 1

To explain 'why' Android has the 'runOnUiThread()' option, it is important to understand that java is only used to create the bytecode (dex) that Android uses. The code running on the phone is NOT java.

Additionally, Android threads 'can' have a thing called a 'looper'. This 'looper' is what handles 'tasks(technically runnables and messages)' in order via a queue. The 'main ui thread' has by default a looper already attached to it.

That means that your runnable you created was put onto the looper's queue of the main UI thread. (this is why the runnable is NOT instantaneously ran, but will be ran 'quickly'/'soon')

The reason you'd use a runnable to run code on the UI thread is because you are in some other 'background thread' that you created... and want to update the UI in some way. (Only the UI thread can interact with the UI)