Why is it necessary to update the view only in the main thread of the user interface?

In Android, updating the user interface (view) should only be performed on the main (UI) thread because the UI framework itself is not thread-safe. Attempting to modify UI elements from a background thread can lead to unpredictable behavior, crashes, or exceptions.

The main thread is responsible for event handling and rendering the interface, so all UI changes must go through it. To update the UI from other threads, methods that switch execution to the main thread are used, such as runOnUiThread(), Handler, LiveData, or View.post().

Example:

runOnUiThread(() -> {
    textView.setText("Updated from a background thread");
});