Android life cycle

2. Unlike the Windows platform, where Android applications cannot control their life cycles, application components must listen to changes in the state of the application and respond appropriately, paying particular attention to being ready to be terminated at any time.
   
   
4. By default, each Android application runs through their own processes, each running in a separate Dalvik instance, and each application's memory and process management is handled exclusively by the runtime. You can use the Android:process property to run the same application component in a different process, or to have multiple applications share a process
   
   
6. When resources are reclaimed, the order in which the processes are terminated is determined by their application priorities, and the priority of an application is equal to the priority of the component with the highest priority.
   
   
8. When two applications have the same priority, the process that runs the longest in the lower-priority state is first terminated. The priority of a process is also affected by inter-process dependencies, and if an application relies on the service or ContentProvider provided by the second application, the second application will at least have the same priority as the application it supports
   
   
12. Active process: The process of an application that has components interacting with the user, including:
• Active activity, which is in the foreground and responds to user events
• Executing broadcast Receiver for Onreceiver event handler
• Executing service for Onstart,oncreate or OnDestroy event handlers
• Service that is running and has been marked as foreground run
  
  
14. Visible processes: Visible But inactive processes are those that reside "visible activity", for example, when the activity component of a process is partially obscured
16. Start a service process: a process that has already started, and after the system terminates a running service, it tries to restart the service when the resource is available, unless the system is told not to do so
18. Background process: The process of activity that is not visible and does not have any running service
20. Empty processes: To improve overall system performance, Android often keeps them in memory after the end of the application's lifetime, and Android maintains this cache to reduce the start-up time of applications being restarted, which is usually terminated periodically as needed

Android life cycle