Difference Between Ui Thread And Other Threads

I have an app that displays a splash screen. The splash screen activity creates a new Runnable which simply sleeps for 1 second and and then launches the main activity: public void

Solution 1:

Yes, that's fine. startActivity(intent) asks the system to launch your main Activity. You're not actually loading it yourself in the thread you call that from.

Solution 2:

Basically it's a single-thread model where only one thread can modify the UI because the Android UI toolkit is not thread-safe.

It's same in Blackberry as well. See Why are most UI frameworks single-threaded?