How can I create global variable keep remain values around the life cycle of the application regardless which activity running.
You could use application preferences. They are accessible from any activity or piece of code as long as you pass on the Context object, and they are private to the application that uses them, so you don't need to worry about exposing application specific values, unless you deal with routed devices. Even so, you could use hashing or encryption schemes to save the values. Also, these preferences are stored from an application run to the next. Here is some code examples that you can look at.