Android Life cycle

I have no any sence thinking about life cycle in android platform before i finished the first notePad exercise.

There is another big different from the rules of  programming with C# or C++.

Life cycle can make us to use system resource efficiently.  We should be ware of that the process of any application don't belong to theirselves.Instead, it's determined by the system through a combination of the parts of the application,how important these parts are to the user,and how much overall memery are available in the system.