popup in flutter code example

Example 1: flutter alertdialog

create a methos _showDialog
then call it in your state

// user defined function
  void _showDialog() {
    // flutter defined function
    showDialog(
      context: context,
      builder: (BuildContext context) {
        // return object of type Dialog
        return AlertDialog(
          title: new Text("Alert Dialog title"),
          content: new Text("Alert Dialog body"),
          actions: <Widget>[
            // usually buttons at the bottom of the dialog
            new FlatButton(
              child: new Text("Close"),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }

Example 2: alertdialog flutter

showAlertDialog(BuildContext context) {

  // set up the button
  Widget okButton = FlatButton(
    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;
    },
  );
}

Example 3: popup flutter

import 'package:flutter/material.dart';

void main() {
  runApp(new MaterialApp(home: new MyApp()));
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final _formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Flutter"),
      ),
      body: Center(
        child: RaisedButton(
          onPressed: () {
            showDialog(
                context: context,
                builder: (BuildContext context) {
                  return AlertDialog(
                    content: Stack(
                      overflow: Overflow.visible,
                      children: <Widget>[
                        Positioned(
                          right: -40.0,
                          top: -40.0,
                          child: InkResponse(
                            onTap: () {
                              Navigator.of(context).pop();
                            },
                            child: CircleAvatar(
                              child: Icon(Icons.close),
                              backgroundColor: Colors.red,
                            ),
                          ),
                        ),
                        Form(
                          key: _formKey,
                          child: Column(
                            mainAxisSize: MainAxisSize.min,
                            children: <Widget>[
                              Padding(
                                padding: EdgeInsets.all(8.0),
                                child: TextFormField(),
                              ),
                              Padding(
                                padding: EdgeInsets.all(8.0),
                                child: TextFormField(),
                              ),
                              Padding(
                                padding: const EdgeInsets.all(8.0),
                                child: RaisedButton(
                                  child: Text("Submitß"),
                                  onPressed: () {
                                    if (_formKey.currentState.validate()) {
                                      _formKey.currentState.save();
                                    }
                                  },
                                ),
                              )
                            ],
                          ),
                        ),
                      ],
                    ),
                  );
                });
          },
          child: Text("Open Popup"),
        ),
      ),
    );
  }
}