I'm working on my android app, and now is perfectly working.
How can I save the whole project so that if I make changes and want to get back to the previous state I can get everything back as it was.
I get my app working and I call such state: version 1.0.
To improve my app I modify the various file and get to: version 1.3.
Now, I made a mess with version 1.3 and want to get back, how can I get to version 1.0?
Use GIT and create branch or tag for your project version. You can check out to any previous version of project where you committed out any change or tagged. Better you check out tutorial like http://www.tutorialspoint.com/git/