`SnackBar` is definitely the right class to use, as pointed out by Darky.
[![Snackbar][1]][1]
One tricky thing about `showSnackBar` is getting to the `ScaffoldState`, if you're trying to call `showSnackBar` within the build method where you construct your `Scaffold`.
You might see an error like this, which includes some text explaining how to solve the problem.
```lang-none
══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
The following assertion was thrown while handling a gesture:
Scaffold.of() called with a context that does not contain a Scaffold.
No Scaffold ancestor could be found starting from the context that was passed to Scaffold.of(). This
usually happens when the context provided is from the same StatefulWidget as that whose build
function actually creates the Scaffold widget being sought.
There are several ways to avoid this problem. The simplest is to use a Builder to get a context that
is "under" the Scaffold. For an example of this, please see the documentation for Scaffold.of():
[To see links please register here]
A more efficient solution is to split your build function into several widgets. This introduces a
new context from which you can obtain the Scaffold. In this solution, you would have an outer widget
that creates the Scaffold populated by instances of your new inner widgets, and then in these inner
widgets you would use Scaffold.of().
A less elegant but more expedient solution is assign a GlobalKey to the Scaffold, then use the
key.currentState property to obtain the ScaffoldState rather than using the Scaffold.of() function.
The context used was:
MyHomePage
When the exception was thrown, this was the stack:
#0 Scaffold.of (package:flutter/src/material/scaffold.dart:444:5)
#1 MyHomePage.build.<anonymous closure> (/Users/jackson/Library/Developer/CoreSimulator/Devices/7072C907-DBAD-44FE-8F40-0257442C51D9/data/Containers/Data/Application/77FEC1A4-1453-442C-8208-96E0323DEFB2/tmp/so_scratch2Tkq9Jb/so_scratch2/lib/main.dart:23:24)
#2 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:323:14)
#3 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:375:30)
#4 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
#5 TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:149:9)
#6 TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:119:7)
#7 GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
#8 BindingBase&SchedulerBinding&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:147:20)
#9 BindingBase&SchedulerBinding&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
#10 BindingBase&SchedulerBinding&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
#11 BindingBase&SchedulerBinding&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
#12 BindingBase&SchedulerBinding&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
#13 _invoke1 (file:///b/build/slave/Mac_Engine/build/src/flutter/lib/ui/hooks.dart:100)
#14 _dispatchPointerDataPacket (file:///b/build/slave/Mac_Engine/build/src/flutter/lib/ui/hooks.dart:58)
Handler: onTap
Recognizer:
TapGestureRecognizer#69dbc(debugOwner: GestureDetector, state: ready)
════════════════════════════════════════════════════════════════════════════════════════════════════
```
You can either pass a `GlobalKey` to your `Scaffold` constructor:
class MyHomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
final key = new GlobalKey<ScaffoldState>();
return new Scaffold(
key: key,
floatingActionButton: new Builder(
builder: (BuildContext context) {
return new FloatingActionButton(
onPressed: () {
key.currentState.showSnackBar(new SnackBar(
content: new Text("Sending Message"),
));
},
tooltip: 'Increment',
child: new Icon(Icons.add),
);
}
),
);
}
}
Or you can use a `Builder` to create a `BuildContext` that is a child of the Scaffold.
class MyHomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new Scaffold(
floatingActionButton: new Builder(
builder: (BuildContext context) {
return new FloatingActionButton(
onPressed: () {
Scaffold.of(context).showSnackBar(new SnackBar(
content: new Text("Sending Message"),
));
},
tooltip: 'Increment',
child: new Icon(Icons.add),
);
}
),
);
}
}
Finally, you could split your widget into multiple classes, which is the best long-term approach.
[1]:
]
