What is the difference between an Android Activity and Service

Am having a great confusion between activity and service. My aim is to run a music player. In most of the document said, to run a background work for an activity you should use service. But its possible to invoke a player from a thread created by an 开发者_如何学Cactivity itself. Moreover, the thread wont destroy even if the activity destroyed.

If so, what is the usage of service here ? Why should we use service and when to use service ?

Plz clarify my doubt !

Thanks in advance.

Activity is a GUI and service is non-gui thread which can run in the background. Some more details here.

Activity An Activity is an application component that provides a screen with which users can interact in order to do something, such as dial the phone, take a photo, send an email, or view a map. Each activity is given a window in which to draw its user interface. The window typically fills the screen, but may be smaller than the screen and float on top of other windows.

Service

*A Service is an application component that can perform long-running operations in the background and does not provide a user interface. Another application component can start a service and it will continue to run in the background even if the user switches to another application. Additionally, a component can bind to a service to interact with it and even perform interprocess communication (IPC). For example, a service might handle network transactions, play music, perform file I/O, or interact with a content provider, all from the background. A service can essentially take two forms:

Started A service is "started" when an application component (such as an activity) starts it by calling startService(). Once started, a service can run in the background indefinitely, even if the component that started it is destroyed. Usually, a started service performs a single operation and does not return a result to the caller. For example, it might download or upload a file over the network. When the operation is done, the service should stop itself. Bound A service is "bound" when an application component binds to it by calling bindService(). A bound service offers a client-server interface that allows components to interact with the service, send requests, get results, and even do so across processes with interprocess communication (IPC). A bound service runs only as long as another application component is bound to it. Multiple components can bind to the service at once, but when all of them unbind, the service is destroyed.*

This may help you to refer for activity

for services you can check this link

Choosing between a service and a thread A service is simply a component that can run in the background, even when the user is not interacting with your application, so you should create a service only if that is what you need.

If you must perform work outside of your main thread, but only while the user is interacting with your application, you should instead create a new thread in the context of another application component. For example, if you want to play some music, but only while your activity is running, you might create a thread in onCreate(), start running it in onStart(), and stop it in onStop(). Also consider using thread pools and executors from the java.util.concurrent package or Kotlin coroutines instead of the traditional Thread class. See the Threading on Android document for more information about moving execution to background threads.

Remember that if you do use a service, it still runs in your application's main thread by default, so you should still create a new thread within the service if it performs intensive or blocking operations.

Source: https://developer.android.com/guide/components/services

I hope this answers your question perfectly.