Briefly describe the difference between the lifecycle of an activity and a service

In the activity lifecycle, the system calls the methods set in the app lifecycle, and these lifecycle methods act like a pyramid at the first level. Each stage of an activity's lifecycle corresponds to a step in the pyramid.

When the system creates a new activity instance, the method moves from the bottom of the tower to the top of the tower. When it's at the top of the pyramid, the activity is in the user's foreground, and the user can interact with the activity. When a user wants to leave an activity, the system calls another series of methods to move the state of the activity from top to bottom.

In some cases, the activity only completes a partial state transition, waits for the user's instructions, and then returns to the top of the tower.

Depending on the complexity of your activities, you may not have to implement all lifecycle approaches. However, it's important to understand what each lifecycle function means to ensure that your application is functioning correctly as expected by your users.

To properly implement the lifecycle approach so that the application behaves correctly, you need to pay attention to the following:

Make sure that when users use you, the app can answer** or switch to a different app without crashing. Ensure that your application doesn't consume system resources when not in use by users.

Ensure that users can continue their previous work when switching back to yours from another app, and that they don't crash or lose user data when switching user screens or other actions.

The front end of the activity is displayed, just like the window in Windows, and the service is secretly doing things in the back, and you may not know that he is doing it, but in fact he is doing it. Android's service is not loaded by a process like mobile, it can be started in activity, broadcast, and started with the start method can be served until the stop method is called, and the binding starts with the bound object.

1. Activity is the core concept of Android applications, in short, Activity is the user interaction manager, with a visual interface presentation, and the difference between Service and Activity is that it runs in the background and has no interface presentation.

2. The slight difference between service and activity in the use of intent is the difference in the value of the intent.

The lifecycle of activities and services.

The life cycle of the activity is controlled by the system, the service is controlled by the program, the service cannot be started by itself, and the service does not interact with the user.

3. The life cycle of the service.

The lifecycle methods of service are a bit less than activity, only oncreate, onstart, ondestroy

There are two ways to start a service, and they have different effects on the service lifecycle.

This is the diagram that refers to when several ** methods of the activity are called.