the hierarchy of processes in Android is as follows (high-to-low importance):
1, the front-end process. As the name implies, the front-end process is currently displayed on the screen and user interaction process, the number of front-end processes in the system, and this process is the most impact on the user experience, only the system's memory is scarce enough to maintain and the user's basic interaction when the front-end process is destroyed. This process is therefore of the highest importance.
2, visible process. Visible process also has a visual interface, but currently not the topmost interface (the topmost interface in the front-end process), the visible process calls OnPause (), visible process is less important than the front-end process, but the interaction is still very large, because the user may switch over at any time, So the system won't easily destroy it.
3, the service process. A service process, which calls the StartService (), is the daemon that is said in Unix, is not visible to the user, but ensures that some important events are monitored or maintained in certain States, such as network data transmission, background music playback, Such processes are not sufficient and are destroyed in order to ensure the smooth running of the front-end interaction.
4, the background process. This is called the background process may be confused with the general sense of the background process, to show that the background process in Android is called OnStop (), can be understood as the user does not have a desire to interact with the process, so the background process here is a bit "to destroy" meaning.
5, empty process. This is a system caching mechanism, is actually a process shell, when a new process is created, this empty process can speed up the process creation, when the system memory is low, first destroy the empty process.
Summarize the process in Android
