Learning Android™ Application Programming: A Hands-On Guide to Building Android Applications

Returning from the Settings Activity with a Back Button

To be certified as an Android device, all devices must have some sort of back button. Most phones have a physical button, but some versions of Android have an onscreen button instead of a physical one. Users who aren’t familiar with the Android OS may not know how to use the system back button.

Because the use of the back button is not consistent across all applications, it is sometimes referred to as the “mystery button.” For example, some applications use the back button to return to a previous screen (activity). Other applications may use it to close the onscreen keyboard or even to return to the home screen. Or the back button may return to the most recent screen (activity) in the previous ...