Showing a Snackbar from inside a Service
Solution 1
The Snackbar
needs a View
to be displayed, so if you want to show snackbars on your app depending on the state of your Service
you'll have to either bind it to your Activity
or broadcast a message through the LocalBroadcastManager
and show a message on your View
.
I don't think there's any other way around it, you'll have to communicate with your Activity
or Fragment
somehow.
Snackbars are not like Toasts that only need a context, so if you want to display it out of your app, I believe you can't with the class provided by Android.
As from the design guidelines:
Placement
Snackbars appear above most elements on screen, and they are equal in elevation to the floating action button. However, they are lower in elevation than dialogs, bottom sheets, and navigation drawers.
It's not explicit, but you can reach the conclusion that it'll only display inside your app views. So, again, you'll have to communicate with your visible view somehow.
Snippets on broadcasting a message:
Sender (on your Service)
private void doSendBroadcast(String message) {
Intent it = new Intent("EVENT_SNACKBAR");
if (!TextUtils.isEmpty(message))
it.putExtra(EXTRA_RETURN_MESSAGE,message);
LocalBroadcastManager.getInstance(mContext).sendBroadcast(it);
}
Receiver (on your Activity)
private BroadcastReceiver mMessageReceiver = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Other stuff.
mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// Do something
}
};
}
@Override
public void onResume() {
super.onResume();
LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver, new IntentFilter("EVENT_SNACKBAR"));
}
More on bound services here.
And about LocalBroadcastManager
here on this question.
Update: You could also make use of an EventBus to communicate with your visible view, as it works on a Publisher/Subscriber fashion. You could even make use of the concept of Sticky events to make sure the Snackbar
will be displayed once the app is visible again.
Take a look at this answer of mine on how to use the Event Bus.
Solution 2
You could always send a broadcast through the LocalBroadcastManager
in your Service
LocalBroadcastManager.getInstance(this).sendBroadcast(new Intent("SERVICE_DID_SOMETHING"));
And then in the Activity
use a BroadcastReceiver
to show the Snackbar
private final ServiceReceiver _serviceReceiver = new ServiceReceiver();
@Override
protected void onResume() {
super.onResume();
final IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("SERVICE_DID_SOMETHING");
LocalBroadcastManager.getInstance(this).registerReceiver(_serviceReceiver, intentFilter);
}
@Override
protected void onPause() {
super.onPause();
try {
LocalBroadcastManager.getInstance(this).unregisterReceiver(_serviceReceiver);
} catch (Exception ex) {
Log.e(TAG, "Error unregistering ServiceReceiver", ex);
}
}
// region ServiceReceiver
private class ServiceReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
// TODO: Show your Snackbar here...
}
}
// endregion
You can use the Intent
you send to pass additional data if needed and then pull it out in the BroadcastReceiver.onReceive(Context context, Intent intent)
Solution 3
How to create a Snackbar with the application context which is visible across multiple activities: https://stackoverflow.com/a/37707741/1185087
Nouvel Travay
Updated on June 05, 2022Comments
-
Nouvel Travay almost 2 years
When showing a
SnackBar
from inside anActivity
, I have therootView
available. But I need to show aSnackBar
from inside aService
, where I do not have aView
available. How might I accomplish this?As backstory: an activity starts a service to do a task. The
Service
needs to show aSnackBar
depending on situations. I don’t want to Bind to theService
just for that. So how might I accomplish this? Normally I could show aToast
, but I need the user to be able to read the message and confirm so. -
Viral Patel over 8 yearswould appreciate a reason when someone downvotes unless it is by competing answers seeking attention. :)
-
Mauker over 8 yearsThat tends to happen a lot in here. I hate it, it's not constructive.
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Nouvel Travay over 8 yearsThanks for your help. +1. I can only accept one answer, so I flipped a coin. Thanks.
-
Admin over 6 yearsNo, @AndroidMechanic, you must have to pass a view to SnackBar provided with the SDK or this library. You will be able to find 2 constructors. #1
new SnackBar.Builder(this)
-this
as activity. #1new SnackBar.Builder(getActivity().getApplicationContext(), root)
-root
as view root