Chapter 7. GUI Alerts: Menus, Dialogs, Toasts, Snackbars, and Notifications

User interface toolkits as diverse as Java Swing, the Apple Macintosh toolbox, Microsoft Windows, and browser JavaScript all feature the ubiquitous “pop-up menu,” usually in the window-frame version and the context (in-window) form. Android follows this convention, with some variations to be expected due to the smaller screens used on many devices (e.g., pop-up or context menus cover a large portion of the screen).

Those other window systems also feature the ubiquitous “dialog,” a window smaller than the main screen that pops up to notify you of some condition or occurrence and asks you to confirm your acceptance, or asks you to make one of several choices, provide some information, and so on.

Android provides a fairly standard dialog mechanism, as well as a smaller, lighter “pop-up” called a toast. This only appears on the screen for a few seconds, and fades away on its own. Intended for passive notification of low-importance events, it is often used for error notification, although I advise against this usage. There is also a Snackbar, which looks like an action bar at the bottom of the screen, but behaves like a toast—it pops up, and then disappears after a few seconds.

And it doesn’t stop there. Android also provides a notification mechanism, which allows you to put text and/or an icon in the notifications bar (top left of the screen). A notification can optionally be accompanied by any combination ...

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