How to implement the FAB (Floating Action Button) in Android apps

Material design introduced some new styles, components and widgets. One of such components is the Floating Action Button (aka FAB). The FAB is a special type of circular button that “floats” in the bottom right of the screen, and displays an ink reaction upon press. It should be used to perform the expected primary action in an activity. This action is called the promoted action. The promoted action, according to material design specifications, should be a positive action (like create, add new, etc) rather than a destructive action (like delete).