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:

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• adding dropdown menu in alert dialog box in flutter
• Show alert dialog on app main screen load automatically
• how to refresh alertdialog in flutter
• Alert Dialog with Rounded corners in flutter

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

Answer 1

showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text("Storage Permission Required"),
          content: const Text(
              "Please grant storage permission to download files."),
          actions: <Widget>[
            TextButton(
              // Use TextButton instead of FlatButton
              child: const Text("CANCEL"),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
            TextButton(
              // Use TextButton instead of FlatButton
              child: const Text("SETTINGS"),
              onPressed: () {
                openAppSettings(); // Open app settings
              },
            ),
          ],
        );
      },
    );

Answer 2

showDialog<String>(
  context: context,
  builder: (BuildContext context) =>
      AlertDialog(
    title: const Text(
      'Invalid Password',
      style: TextStyle(color: Colors.red),
    ),
    content:
        const Text('Create Strong Password'),
    actions: <Widget>[
      Center(
        child: TextButton(
          style: TextButton.styleFrom(
            primary: Colors.white,
            backgroundColor: Colors
                .red, // Background Color
          ),
          onPressed: () => Navigator.pop(
              context, 'Cancel'),
          child: const Text('Cancel'),
        ),
      ),
    ],
  ),
),

Answer 3

If you need a dialog so this code for you. just use showMyDialog() onPress or any inside a function.

 void showMyDialog() {
  showDialog(
  context: context,
  builder: (ctx) => AlertDialog(
    title: const Text("Login Failed!"),
    content: const Text(
      "Invalid credential !! Please check your email or password",
      style: TextStyle(fontSize: 18, fontWeight: FontWeight.w400),
    ),
    actions: <Widget>[
      TextButton(
        onPressed: () {
          Navigator.of(ctx).pop();
        },
        child: Container(
          child: const Text(
            "Try again",
            style: TextStyle(color: Colors.cyan, fontSize: 17),
          ),
        ),
      ),
    ],
  ),
)}

Demo dialog screenshots

hope its helpful😊😊😊

Answer 4

Here is working version of Bakri Bitar's answer without changing it to Stateful Widget:

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


class BlurryDialog extends StatelessWidget {
  final String title;
  final String content;
  final VoidCallback continueCallBack;
  final TextStyle textStyle = const TextStyle(color: Colors.black);

  const BlurryDialog({
    Key? key,
    required this.title,
    required this.content,
    required this.continueCallBack,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return BackdropFilter(
      filter: ImageFilter.blur(sigmaX: 6, sigmaY: 6),
      child:  AlertDialog(
        shape: RoundedRectangleBorder(    // This line is added
            borderRadius: BorderRadius.circular(12),   // Change this value to change the corner radius
        ),
        title: Text(title, style: textStyle, textAlign: TextAlign.center,),
        content: new Text(content, style: textStyle,),
        actions: <Widget>[
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: [
              ElevatedButton(
                child: Text('Yes', style: TextStyle(color: Colors.white)),
                onPressed: () {
                       continueCallBack();
                  Navigator.of(context).pop();
              
                },
                style: ElevatedButton.styleFrom(
                  backgroundColor: Color.fromARGB(255, 54, 139, 244),
                  foregroundColor: Colors.black,
                ),
              ),
               ElevatedButton(
                child: Text('No', style: TextStyle(color: Colors.white)),
                onPressed: () {
                  Navigator.of(context).pop();
                },
                style: ElevatedButton.styleFrom(
                  backgroundColor: Color.fromARGB(255, 54, 139, 244),
                  foregroundColor: Colors.black,
                ),
              ),
            ]),
        ],
      ),
    );
  }
}

You can call it like this:

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

BlurryDialog alert = BlurryDialog(
  title: "Your Title",         // Provide 'title'
  content: "Your Content Text",        // Provide 'content'
  continueCallBack: continueCallBack,   // Provide 'continueCallBack'
);

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

Answer 5

Simple and working solution that I used: Enjoy // Sample can be used for exit dialog box on apps

showAlertDialog(BuildContext context) {

    Widget okButton = TextButton(
      child: const Text("Leave now",style: TextStyle(color: Colors.red),),
      onPressed: () { SystemNavigator.pop(); },
    );

    Widget nopeButton = TextButton(
      child: const Text("Stay here"),
      onPressed: () { Navigator.pop(context); },
    );

    AlertDialog alert = AlertDialog(
      title: const Text("Leave"),
      content: const Text("Are you sure you want to leave?"),
      actions: [
        nopeButton,
        okButton,
      ],
    );

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

Answer 6

Just to add to the great answers - the best package I found is:

adaptive_dialog: ^1.8.0+1

For a one OK button the best thing I found is using showOkAlertDialog

Implementation:

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

    Widget build(BuildContext context) {
      return Container(
        child: Center(
            child: IconButton(
          icon: Icon(
            Icons.info,
          ),
          onPressed: () => showOkAlertDialog(
            context: context,
            okLabel: 'OK',
            title: 'Title',
            message: 'This is the message',
          ),
        )),
      );
    }

Clean and dismisses when you click 'Ok'.

Answer 7

Minumum code for alert dialog

showDialog(
  context: context,
  builder: (_) => AlertDialog(
    title: Text('Title'),
    content: Text(
      'Content widget',
    ),
  ),
);

Answer 8

This code works and demonstrates how to obtain the button value pressed by the user:

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const Center(
          child: MyStatelessWidget(),
        ),
      ),
    );
  }
}

class MyStatelessWidget extends StatelessWidget {
  const MyStatelessWidget({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        // set up the buttons
        Widget cancelButton = TextButton(
          child: Text("Cancel"),
          onPressed: () => Navigator.pop(context, 'Cancel'),
        );
        Widget continueButton = TextButton(
          child: Text("Ok"),
          onPressed: () => Navigator.pop(context, 'Ok'),
        );
        showDialog<String>(
          context: context,
          builder: (BuildContext context) => AlertDialog(
            title: const Text('AlertDialog Title'),
            content: const Text('AlertDialog description'),
            actions: <Widget>[
              cancelButton,
              continueButton,
            ],
          ),
        ).then((value) => print(value));
      },
      child: const Text('Show Dialog'),
    );
  }
}

Pressing on Ok button. then on Cancel button print

Answer 9

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) { ... }

Answer 10

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
}
}

Answer 11

Another easy option to show Dialog is to use stacked_services package

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

Answer 12

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:

Answer 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

Answer 14

I used similar approach, but I wanted to

1. Keep the Dialog code as a widget in a separated file so I can reuse it.
2. 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;
    },
  );
}

Answer 15

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");

Answer 16

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.

Answer 17

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

Answer 18

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.