Medium android interview questions

A Service is an application component that can perform long-running operations in the background . It does not provide a user interface. Once started, a service might continue running for some time, even after the user switches to another application.

The Android platform takes advantage of the Linux user-based protection to identify and isolate app resources . This isolates apps from each other and protects apps and the system from malicious apps. To do this, Android assigns a unique user ID (UID) to each Android application and runs it in its own process.

Playing music in the background is a very common example of services in android. From the time when a user starts the service, music play continuously in the background even if the user switches to another application. The user has to stop the service explicitly in order to pause the music.

An activity represents a single screen with a user interface just like window or frame of Java . Android activity is the subclass of ContextThemeWrapper class. If you have worked with C, C++ or Java programming language then you must have seen that your program starts from main() function.