NetworkOnMainThreadException

In Java, network operations are blocking by nature. Calling a web service, for example, will block the current thread until a response is received or a timeout/error happens. Because blocking the UI thread would mean freezing all the UI – including animations and any other interactions – Android crashes whenever a network operation is made on the UI thread. The NetworkOnMainThreadException exception will be thrown whenever this happens, forcing developers to use a background thread, and thus improving the user experience.