How to make an AlertDialog in Flutter?

Question

I am learning to build apps in Flutter. Now I have come to alert dialogs. I have done them before in Android and iOS, but how do I make an alert in Flutter?

Here are some related SO questions:

I'd like to make a more general canonical Q&A so my answer is below.

Must be check out this, Here is the exact code to create the this :-https://stackoverflow.com/a/63086647/10563627 — Paresh Mangukiya, Jul 25 '20 at 09:28
The Best way to use alert dialog is to create a separate class for the alert dialog and use it in the entire project. Refer this : https://arkapp.medium.com/how-to-use-alert-dialog-in-flutter-a5637346d984 — abdul rehman, Feb 02 '21 at 07:09

Suragch · Accepted Answer · 2021-07-12T03:12:24.290

One Button

showAlertDialog(BuildContext context) {

  // set up the button
  Widget okButton = TextButton(
    child: Text("OK"),
    onPressed: () { },
  );

  // set up the AlertDialog
  AlertDialog alert = AlertDialog(
    title: Text("My title"),
    content: Text("This is my message."),
    actions: [
      okButton,
    ],
  );

  // show the dialog
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return alert;
    },
  );
}

Two Buttons

showAlertDialog(BuildContext context) {

  // set up the buttons
  Widget cancelButton = TextButton(
    child: Text("Cancel"),
    onPressed:  () {},
  );
  Widget continueButton = TextButton(
    child: Text("Continue"),
    onPressed:  () {},
  );

  // set up the AlertDialog
  AlertDialog alert = AlertDialog(
    title: Text("AlertDialog"),
    content: Text("Would you like to continue learning how to use Flutter alerts?"),
    actions: [
      cancelButton,
      continueButton,
    ],
  );

  // show the dialog
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return alert;
    },
  );
}

Three Buttons

showAlertDialog(BuildContext context) {

  // set up the buttons
  Widget remindButton = TextButton(
    child: Text("Remind me later"),
    onPressed:  () {},
  );
  Widget cancelButton = TextButton(
    child: Text("Cancel"),
    onPressed:  () {},
  );
  Widget launchButton = TextButton(
    child: Text("Launch missile"),
    onPressed:  () {},
  );

  // set up the AlertDialog
  AlertDialog alert = AlertDialog(
    title: Text("Notice"),
    content: Text("Launching this missile will destroy the entire universe. Is this what you intended to do?"),
    actions: [
      remindButton,
      cancelButton,
      launchButton,
    ],
  );

  // show the dialog
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return alert;
    },
  );
}

Handling button presses

The onPressed callback for the buttons in the examples above were empty, but you could add something like this:

Widget launchButton = TextButton(
  child: Text("Launch missile"),
  onPressed:  () {
    Navigator.of(context).pop(); // dismiss dialog
    launchMissile();
  },
);

If you make the callback null, then the button will be disabled.

onPressed: null,

Supplemental code

Here is the code for main.dart in case you weren't getting the functions above to run.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter',
      home: Scaffold(
        appBar: AppBar(
          title: Text('Flutter'),
        ),
        body: MyLayout()),
    );
  }
}

class MyLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: ElevatedButton(
        child: Text('Show alert'),
        onPressed: () {
          showAlertDialog(context);
        },
      ),
    );
  }
}

// replace this function with the examples above
showAlertDialog(BuildContext context) { ... }

Navigator.of(context).pop(); does not dismiss the dialog, but the screen beneath it. The dialog presists. — GunJack, Jun 27 '20 at 05:46
@GunJack, It sounds like you are using a different setup than I have here. There is only a single screen in the example here. — Suragch, Jun 27 '20 at 05:49
Yeah I think because I using multiple navigators. Calling showDialog directly in the button's onPressed method works. But calling showAlertDialog function from onPressed makes for the weird behaviour. — GunJack, Jun 27 '20 at 14:34
I tried this and the code after `showAlertDialog` runs immediately after the dialog pops up and doesnt wait for the choice to be done. How can I ensure the next code runs after a choice is selected? I tried using await and still no luck — West, Jul 14 '21 at 07:36
@West, put the code that you want to run afterward in the `onPressed` callback of the dialog button. — Suragch, Jul 14 '21 at 08:30
Great answer! Also if you want to build your own custom dialog you can do it by using `Dialog` widget. It is as the same as above answer, but instead of using `AlertDialog` this class can return any custom widget that you build so it will be displayed as the popup. Read more in this [medium article](https://medium.com/flutterdevs/custom-dialog-in-flutter-7ca5c2a8d33a) — Hasintha Abeykoon, Jul 19 '21 at 17:15
Do I need to have bool state implementation in all widgets that needs to show the dialog component? — lolelo, Aug 31 '21 at 11:30
@Suragch I missed that `showDialog` was a method from the `package:flutter/src/material/dialog.dart`. I thought I had to do conditional rendering to show the dialog. — lolelo, Sep 01 '21 at 08:30

Bakri Bitar · Answer 2 · 2020-06-12T13:51:56.117

I used similar approach, but I wanted to

Keep the Dialog code as a widget in a separated file so I can reuse it.
Blurr the background when the dialog is shown.

Code: 1. alertDialog_widget.dart

import 'dart:ui';
import 'package:flutter/material.dart';


class BlurryDialog extends StatelessWidget {

  String title;
  String content;
  VoidCallback continueCallBack;

  BlurryDialog(this.title, this.content, this.continueCallBack);
  TextStyle textStyle = TextStyle (color: Colors.black);

  @override
  Widget build(BuildContext context) {
    return BackdropFilter(
      filter: ImageFilter.blur(sigmaX: 6, sigmaY: 6),
      child:  AlertDialog(
      title: new Text(title,style: textStyle,),
      content: new Text(content, style: textStyle,),
      actions: <Widget>[
        new FlatButton(
          child: new Text("Continue"),
           onPressed: () {
            continueCallBack();
          },
        ),
        new FlatButton(
          child: Text("Cancel"),
          onPressed: () {
            Navigator.of(context).pop();
          },
        ),
      ],
      ));
  }
}

You can call this in main (or wherever you want) by creating a new method like:

 _showDialog(BuildContext context)
{

  VoidCallback continueCallBack = () => {
 Navigator.of(context).pop(),
    // code on continue comes here

  };
  BlurryDialog  alert = BlurryDialog("Abort","Are you sure you want to abort this operation?",continueCallBack);


  showDialog(
    context: context,
    builder: (BuildContext context) {
      return alert;
    },
  );
}

You need to remove the dialog after user choose Continue option. So I needed to add Navigator.of(context).pop(); after continueCallback() — Reginaldo Rigo, Jun 12 '20 at 13:13
@ReginaldoRigo yes. I had to add it in my code as well. Just added it to the answer. — Bakri Bitar, Jun 12 '20 at 13:33
This worked for me but I had to convert BlurryDialog to a StatefulWidget and declare the 2 Strings and VoidCallback as finals. — Rivers Cuomo, Feb 14 '21 at 16:39

score 19 · Answer 3 · edited Jul 18 '20 at 15:13

You can use this code snippet for creating a two buttoned Alert box,

import 'package:flutter/material.dart';

class BaseAlertDialog extends StatelessWidget {

  //When creating please recheck 'context' if there is an error!

  Color _color = Color.fromARGB(220, 117, 218 ,255);

  String _title;
  String _content;
  String _yes;
  String _no;
  Function _yesOnPressed;
  Function _noOnPressed;

  BaseAlertDialog({String title, String content, Function yesOnPressed, Function noOnPressed, String yes = "Yes", String no = "No"}){
    this._title = title;
    this._content = content;
    this._yesOnPressed = yesOnPressed;
    this._noOnPressed = noOnPressed;
    this._yes = yes;
    this._no = no;
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: new Text(this._title),
      content: new Text(this._content),
      backgroundColor: this._color,
      shape:
          RoundedRectangleBorder(borderRadius: new BorderRadius.circular(15)),
      actions: <Widget>[
        new FlatButton(
          child: new Text(this._yes),
          textColor: Colors.greenAccent,
          onPressed: () {
            this._yesOnPressed();
          },
        ),
        new FlatButton(
          child: Text(this._no),
          textColor: Colors.redAccent,
          onPressed: () {
            this._noOnPressed();
          },
        ),
      ],
    );
  }
}

To show the dialog you can have a method that calls it NB after importing BaseAlertDialog class

_confirmRegister() {
var baseDialog = BaseAlertDialog(
    title: "Confirm Registration",
    content: "I Agree that the information provided is correct",
    yesOnPressed: () {},
    noOnPressed: () {},
    yes: "Agree",
    no: "Cancel");
showDialog(context: context, builder: (BuildContext context) => baseDialog);
}

OUTPUT WILL BE LIKE THIS

In Suragch's answer above, he has provided all the code to make an example app, where you tap the button and the dialog shows. — Rune Hansen, Apr 14 '20 at 21:12

live-love · Answer 4 · 2021-01-03T17:26:52.340

Here is a shorter, but complete code.

If you need a dialog with only one button:

await showDialog(
      context: context,
      builder: (context) => new AlertDialog(
        title: new Text('Message'),
        content: Text(
                'Your file is saved.'),
        actions: <Widget>[
          new FlatButton(
            onPressed: () {
              Navigator.of(context, rootNavigator: true)
                  .pop(); // dismisses only the dialog and returns nothing
            },
            child: new Text('OK'),
          ),
        ],
      ),
    );

If you need a dialog with Yes/No buttons:

onPressed: () async {
bool result = await showDialog(
  context: context,
  builder: (context) {
    return AlertDialog(
      title: Text('Confirmation'),
      content: Text('Do you want to save?'),
      actions: <Widget>[
        new FlatButton(
          onPressed: () {
            Navigator.of(context, rootNavigator: true)
                .pop(false); // dismisses only the dialog and returns false
          },
          child: Text('No'),
        ),
        FlatButton(
          onPressed: () {
            Navigator.of(context, rootNavigator: true)
                .pop(true); // dismisses only the dialog and returns true
          },
          child: Text('Yes'),
        ),
      ],
    );
  },
);

if (result) {
  if (missingvalue) {
    Scaffold.of(context).showSnackBar(new SnackBar(
      content: new Text('Missing Value'),
    ));
  } else {
    saveObject();
    Navigator.of(context).pop(_myObject); // dismisses the entire widget
  }
} else {
  Navigator.of(context).pop(_myObject); // dismisses the entire widget
}
}

score 14 · Answer 5 · answered Sep 10 '20 at 15:43

Simply used this custom dialog class which field you not needed to leave it or make it null so this customization you got easily.

import 'package:flutter/material.dart';

class CustomAlertDialog extends StatelessWidget {
  final Color bgColor;
  final String title;
  final String message;
  final String positiveBtnText;
  final String negativeBtnText;
  final Function onPostivePressed;
  final Function onNegativePressed;
  final double circularBorderRadius;

  CustomAlertDialog({
    this.title,
    this.message,
    this.circularBorderRadius = 15.0,
    this.bgColor = Colors.white,
    this.positiveBtnText,
    this.negativeBtnText,
    this.onPostivePressed,
    this.onNegativePressed,
  })  : assert(bgColor != null),
        assert(circularBorderRadius != null);

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: title != null ? Text(title) : null,
      content: message != null ? Text(message) : null,
      backgroundColor: bgColor,
      shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(circularBorderRadius)),
      actions: <Widget>[
        negativeBtnText != null
            ? FlatButton(
                child: Text(negativeBtnText),
                textColor: Theme.of(context).accentColor,
                onPressed: () {
                  Navigator.of(context).pop();
                  if (onNegativePressed != null) {
                    onNegativePressed();
                  }
                },
              )
            : null,
        positiveBtnText != null
            ? FlatButton(
                child: Text(positiveBtnText),
                textColor: Theme.of(context).accentColor,
                onPressed: () {
                  if (onPostivePressed != null) {
                    onPostivePressed();
                  }
                },
              )
            : null,
      ],
    );
  }
}

Usage:

var dialog = CustomAlertDialog(
  title: "Logout",
  message: "Are you sure, do you want to logout?",
  onPostivePressed: () {},
  positiveBtnText: 'Yes',
  negativeBtnText: 'No');
showDialog(
  context: context,
  builder: (BuildContext context) => dialog);

Output:

score 7 · Answer 6 · answered Dec 20 '18 at 16:31

Or you can use RFlutter Alert library for that. It is easily customizable and easy-to-use. Its default style includes rounded corners and you can add buttons as much as you want.

Basic Alert:

Alert(context: context, title: "RFLUTTER", desc: "Flutter is awesome.").show();

Alert with Button:

Alert(
    context: context,
    type: AlertType.error,
    title: "RFLUTTER ALERT",
    desc: "Flutter is more awesome with RFlutter Alert.",
    buttons: [
    DialogButton(
        child: Text(
        "COOL",
        style: TextStyle(color: Colors.white, fontSize: 20),
        ),
        onPressed: () => Navigator.pop(context),
        width: 120,
    )
    ],
).show();

You can also define generic alert styles.

*I'm one of developer of RFlutter Alert.

Nice. Looks like it could save some boilerplate and is pretty customizable. — Suragch, Dec 20 '18 at 16:55
Is there a way to pass different functions to the onPressed parameter of the Alert so I don't have to keep making new alerts for everything?? — Simran Aswani, Apr 14 '20 at 14:06

score 5 · Answer 7 · answered Nov 06 '19 at 04:18

5

If you want beautiful and responsive alert dialog then you can use flutter packages like

rflutter alert ,fancy dialog,rich alert,sweet alert dialogs,easy dialog & easy alert

These alerts are good looking and responsive. Among them rflutter alert is the best. currently I am using rflutter alert for my apps.

answered Nov 06 '19 at 04:18

raman raman

1,437
1
18
32

links along with package names would be helpful – Istiaque Ahmed Mar 27 '20 at 13:28
1

I'm developer RFlutter Alert and thanks for your nice comment @raman raman . – ibrahimdevs Sep 17 '20 at 06:44

score 4 · Answer 8 · answered Apr 25 '20 at 15:23

showAlertDialog(BuildContext context, String message, String heading,
      String buttonAcceptTitle, String buttonCancelTitle) {
    // set up the buttons
    Widget cancelButton = FlatButton(
      child: Text(buttonCancelTitle),
      onPressed: () {},
    );
    Widget continueButton = FlatButton(
      child: Text(buttonAcceptTitle),
      onPressed: () {

      },
    );

    // set up the AlertDialog
    AlertDialog alert = AlertDialog(
      title: Text(heading),
      content: Text(message),
      actions: [
        cancelButton,
        continueButton,
      ],
    );

    // show the dialog
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return alert;
      },
    );
  }

called like:

showAlertDialog(context, 'Are you sure you want to delete?', "AppName" , "Ok", "Cancel");

score 2 · Answer 9 · edited Jun 20 '20 at 09:12

Check out Flutter Dropdown Banner to easily alert users of events and prompt action without having to manage the complexity of presenting, delaying, and dismissing the component.

To set it up:

import 'packages:dropdown_banner/dropdown_banner.dart';
...
class MainApp extends StatelessWidget {
  ...
  @override
  Widget build(BuildContext context) {
    final navigatorKey = GlobalKey<NavigatorState>();
    ...
    return MaterialApp(
        ...
        home: DropdownBanner(
          child: Scaffold(...),
          navigatorKey: navigatorKey,
        ),
    );
  }
}

To use it:

import 'packages:dropdown_banner/dropdown_banner.dart';
...
class SomeClass {
  ...
  void doSomethingThenFail() {
    DropdownBanner.showBanner(
      text: 'Failed to complete network request',
      color: Colors.red,
      textStyle: TextStyle(color: Colors.white),
    );
  }
}

Click here to see an example

When posting links as answers, try to add some actual text/code to explain why you gave the link, and/or how to use the linked content. Otherwise, such replies should be comments. — Adrian Mole, Sep 18 '19 at 15:56
@Adrian I added some example code as per your recommendation. — Bruce Brookshire, Sep 19 '19 at 16:07

Javeed Ishaq · Answer 10 · 2020-12-25T18:33:38.083

0

Another easy option to show Dialog is to use stacked_services package

 _dialogService.showDialog(
      title: "Title",
      description: "Dialog message Tex",
         );
     });

edited Dec 25 '20 at 18:33

answered Dec 25 '20 at 18:21

Javeed Ishaq

3,991
2
30
47