How to ensure the execution of certain actions in the main thread from another thread?

In Android, to perform actions on the main (UI) thread from another thread, you can use the Handler class or runOnUiThread.

Example using runOnUiThread in an Activity:

runOnUiThread(new Runnable() {
    @Override
    public void run() {
        // Code to be executed on the main thread
        textView.setText("Updated from another thread");
    }
});

You can also use a Handler associated with the main thread's Looper:

Handler mainHandler = new Handler(Looper.getMainLooper());

mainHandler.post(new Runnable() {
    @Override
    public void run() {
        // Actions on the main thread
    }
});

In modern applications, architectural components and coroutines are often used, but these methods are standard for basic understanding.