How to ensure that operations do not block the user interface?

To prevent operations from blocking the user interface in Android, they should be performed in a background thread rather than the main (UI) thread. You can use:

• AsyncTask (deprecated but still common in legacy code)
• HandlerThread or Handler
• ExecutorService
• Kotlin Coroutines (modern and recommended approach)
• RxJava

For example, with coroutines, you can do the following:

GlobalScope.launch(Dispatchers.Main) {
    val result = withContext(Dispatchers.IO) {
        // Long operation, e.g., network request
        fetchData()
    }
    // Update UI with the result
    textView.text = result
}

Thus, heavy work is performed in a background thread (IO), and the interface is updated in the main thread.