Android - Snackbar vs Toast - usage and difference

We have been using just Toasts in our application so far and as we are planning to adopt some new features from Support Design Library I am wondering what's the recommended usage for Snackbar vs. Toast.

I have been reading on the google material snackbar doc.

Snackbars provide lightweight feedback about an operation in a small popup at the base of the screen on mobile and at the lower left on desktop. They are above all over elements on screen, including the FAB.

and toasts.

Android also provides a capsule-shaped toast, primarily used for system messaging. Toasts are similar to snackbars but do not contain actions and cannot be swiped off screen.

I understand what they do but I am a bit confused when to use what. Does it mean that:

• If I don't require user interaction I would use a toast?
• What is meant by "system messaging"? Does that apply to displaying information when something important happened between my app and the Android system?
• What I like is the swipe off screen feature - would that be a reason to start replacing toasts with snackbars? (this is a bit opinion based question though)

If I don't require user interaction I would use a toast?

You can still use Snackbar. It is not mandatory to have an action with Snackbar.

What is meant by "system messaging"? Does that apply to displaying information when something important happened between my app and the Android system?

I believe this means that Toasts are to be used if there are some messages pertaining to the system. Either android as a whole or some background service you may be running. E.g. Text-To-Speech is not installed. OR No Email client found.

What I like is the swipe off screen feature - would that be a reason to start replacing toasts with Snackbar? (this is a bit opinion based question though)

That is one reason. But there are several other plus points. For an example: Your toast remains on screen even when the activity is finished. Snackbar doesn't. There is less confusion if the toast does not popup (or keep popping up in case of multiple Toast creation in sequence) long after the app is exited. This will not happen with Snackbar.

More than everything: I suggest if you are thinking, you should switch. SnackBars look far better than Toasts.

I would like to add a small comparison between toast and snack bar. In my opinion if your intention is to present a warning or info that need user interaction/acknowledgement, you should use a snack bar. If it is just an info message that doesn't need any user acknowledgement you can use toast.

Toast:

1. Toast was added in API Level 1
2. Basically Activity is not required (Can be shown on Android home or even above other apps)
3. It can’t perform an action based on User input
4. It can’t be dismissed by swiping
5. It can’t handle user input like Swipe, Click etc.
6. Good for showing info messages to user

SnackBar:

1. SnackBar was added in API Level 23
2. It can be showed inside an activity of the Applications
3. It can perform an action
4. It can be dismissed by swiping
5. It can handle user input
6. Good for showing warning/info type messages to user that needs attention

Usage of SnackBar and Toast:

SnackBar:

SnackBar can be used in the areas where a simple popup message needs to be displayed along with an option to perform action. For Example: In GMail application, when you delete Mail, quick SnackBar display at the bottom with Message ‘1 Deleted’ with an action button ‘Undo’. On pressing the ‘Undo’ action button, the deleted mail will be restored.

Toast:

Toast can be used in the areas where System messages need to be displayed.

For Example:

When your App tries to download JSON from remote server but it fails due to Server Timeout or No resource found, you just need to display the error message saying that ‘Error Occurred’. But understand the Toast message cannot be dismissed by swiping. If you still want to have the capability of dismissing it in your App, go for SnackBar.

According to the official documentation at Pop-up messages overview:

Note: The Snackbar class supersedes Toast. While Toast is currently still supported, Snackbar is now the preferred way to display brief, transient messages to the user.

and (Material Design) Snackbars's documentation:

Related concepts: Android also provides a Toast class with a similar API that can be used for displaying system-level notifications. Generally, snackbars are the preferred mechanism for displaying feedback messages to users, as they can be displayed in the context of the UI where the action occurred. Reserve Toast for cases where this cannot be done.