How to use Functions of another File in Dart / Flutter?

Question

I have a Flutter app where I'm using the flutter_web_view package. I'm using it over several different files and would love to create its own file and simply reference with the _launchwebview function anywhere in my app because there are several lines of code needed in order to make it work. I know how to reference files and pass information but not methods/functions. Here is the class code...

import 'package:flutter/material.dart'; import 'package:flutter_web_view/flutter_web_view.dart';  class ShopClass extends StatefulWidget {   @override   ShopClassState createState() => new ShopClassState(); }  class ShopClassState extends State<ShopClass> {   String _redirectedToUrl;   FlutterWebView flutterWebView = new FlutterWebView();   bool _isLoading = false;    @override   initState() {     super.initState();   }    @override   Widget build(BuildContext context) {     Widget leading;     if (_isLoading) {       leading = new CircularProgressIndicator();     }     var columnItems = <Widget>[       new MaterialButton(           onPressed: launchWebViewExample, child: new Text("Launch"))     ];     if (_redirectedToUrl != null) {       columnItems.add(new Text("Redirected to $_redirectedToUrl"));     }     var app = new MaterialApp(       home: new Scaffold(         appBar: new AppBar(           leading: leading,         ),         body: new Column(           children: columnItems,         ),       ),     );     return app;   }     void launchWebViewExample() {     if (flutterWebView.isLaunched) {       return;     }      flutterWebView.launch("https://apptreesoftware.com",         headers: {           "X-SOME-HEADER": "MyCustomHeader",         },         javaScriptEnabled: false,         toolbarActions: [           new ToolbarAction("Dismiss", 1),           new ToolbarAction("Reload", 2)         ],         barColor: Colors.green,         tintColor: Colors.white);     flutterWebView.onToolbarAction.listen((identifier) {       switch (identifier) {         case 1:           flutterWebView.dismiss();           break;         case 2:           reload();           break;       }     });     flutterWebView.listenForRedirect("mobile://test.com", true);      flutterWebView.onWebViewDidStartLoading.listen((url) {       setState(() => _isLoading = true);     });     flutterWebView.onWebViewDidLoad.listen((url) {       setState(() => _isLoading = false);     });     flutterWebView.onRedirect.listen((url) {       flutterWebView.dismiss();       setState(() => _redirectedToUrl = url);     });   }      void reload() {     flutterWebView.load(       "https://google.com",       headers: {         "X-SOME-HEADER": "MyCustomHeader",       },     );   } } 

How can I use launchWebViewExample in another class?

Answer 1

You can write a file with just that function, like:

test.dart

void launchWebView () {   print("1234"); } 

and then import that file like this:

main.dart

import "test.dart";  class _MyHomePageState extends State<MyHomePage> {    @override    Widget build(BuildContext context) {        launchWebView(); 

It is not really clean, but you can do that. Alternatively you can use a class with a static method like:

class test {     static void foo() {         print("1234");     } } 

and then in your code invoke it like that (after the import):

test.foo();