在Android中的其他nPause（）方法中保存具有应用状态的文件

I want to write a incomplete app state to a file if user leaves the app without saving the state. I believe I have to use onPause(). Is this recommended practice? (In onPause() i am going to encrypt the string and then create a file and store it, so bit time consuming).I want to write a incomplete app state to a fil