What is Dart?

Dart is a general-purpose, object-oriented programming language developed by Google. It is optimized for building mobile, web, and server applications, and it is especially well known as the language behind the Flutter framework, which is used to create natively compiled applications for mobile, web, and desktop from a single codebase.

Dart was first introduced by Google in 2011 as an alternative to JavaScript, with the goal of making web development easier and more efficient. Over time, Dart has evolved into a versatile language, supporting features like strong typing, asynchronous programming, and modern language constructs like classes, generics, and functional programming features.

While Dart can be used for general programming tasks, its biggest popularity comes from being the language used with Flutter, which has seen tremendous growth in mobile app development. The primary advantage of Dart is its ability to compile to native code, providing fast performance on both mobile and web platforms. Dart also compiles to JavaScript, enabling developers to run Dart code in web browsers.

Major Use Cases of Dart

Dart is used in several areas of software development, with the most notable use cases being in mobile app development, web development, and server-side programming. Here are some major use cases:

1. Mobile Application Development (with Flutter):
   Dart is most commonly used in conjunction with the Flutter framework to develop cross-platform mobile applications for both iOS and Android. Flutter uses Dart as its programming language to build natively compiled applications. This allows developers to write once and deploy on multiple platforms, significantly reducing development time and cost.
   • Example: Popular apps like Google Ads, Alibaba, and Reflectly are built using Flutter and Dart.
2. Web Development:
   Dart can be compiled to JavaScript, allowing developers to build client-side web applications. Dart has a strong focus on performance, and when compiled, it can run efficiently in the browser, providing smooth experiences even for complex web applications.
   • Example: Dart’s web capabilities are utilized in single-page applications (SPAs) where dynamic content needs to be displayed without reloading the entire page.
3. Server-Side Programming:
   Dart can also be used for building server-side applications. Dart provides libraries to handle HTTP requests, manage databases, and support various server-side tasks. This makes it suitable for developing APIs, microservices, or full-fledged backend systems.
   • Example: Using Dart for building RESTful APIs or GraphQL services that handle client requests and respond with data.
4. Desktop Application Development (with Flutter):
   Flutter, along with Dart, is also used for building desktop applications. While it was initially designed for mobile applications, Flutter’s growing support for desktop platforms enables developers to build cross-platform desktop applications for macOS, Windows, and Linux.
   • Example: An accounting or task management application that runs across mobile and desktop with minimal code changes.
5. Command Line Tools and Scripts:
   Dart can be used for writing command-line tools, scripts, and other small utilities. It is well-suited for tasks like automating repetitive processes, creating file management tools, or working with system commands.
   • Example: Writing a Dart script to automate data backup processes or manage system configurations.

How Dart Works Along with Architecture

Dart operates within a flexible and efficient execution model that supports both Just-In-Time (JIT) and Ahead-Of-Time (AOT) compilation, depending on the environment it’s running in. Here is how Dart works in different contexts:

1. Dart Runtime and Virtual Machine:
   Dart can run directly on its own runtime, known as the Dart VM (Virtual Machine). This is especially useful during development because the Dart VM can execute Dart code in a JIT compilation mode, allowing for fast development cycles with features like hot reload and dynamic execution.
   • Just-In-Time (JIT) Compilation: In JIT mode, the Dart code is compiled at runtime into machine code, providing quick iterations during development, such as for Flutter apps. JIT allows you to modify and reload your code without restarting the app, speeding up the development process.
2. Ahead-Of-Time (AOT) Compilation:
   Dart also supports AOT compilation, where the Dart code is compiled into native machine code before the app is executed. AOT is used for production builds where performance is crucial, and it is the primary mode for running mobile applications in Flutter. This ensures that the application runs with fast startup times and high performance on the target platform.
   • AOT compilation is important in mobile development for delivering optimized, fast applications, as it allows the app to run directly on the device without needing an intermediary layer.
3. Dart-to-JavaScript:
   Dart has built-in support for compiling Dart code into JavaScript. This enables Dart applications to run in web browsers by converting Dart code into JavaScript, ensuring compatibility with any modern web browser.
   • This architecture allows Dart developers to write a single codebase that works across web, mobile, and desktop platforms, offering a unified approach to development.
4. Dart and Flutter Framework:
   Dart is tightly integrated with the Flutter framework, where Flutter handles the user interface (UI) layer and Dart handles the business logic. Flutter uses Dart to interact with native components like the device’s hardware, sensors, and camera, while Dart ensures the app remains responsive and performs well across different devices.

Basic Workflow of Dart

The basic workflow of working with Dart typically involves the following steps:

1. Install Dart:
   • Install Dart SDK from the official Dart website. The SDK includes everything needed to run Dart applications, including the Dart VM, libraries, and tools.
2. Create a Dart Project:
   • Create a new directory for your project, then initialize a Dart project by creating a file with a .dart extension (e.g., main.dart). This file will contain your Dart code.
3. Write Dart Code:
   • Dart programs are composed of functions and classes. You can write code to perform tasks such as defining variables, implementing logic, and interacting with external services.
   • Example: void main() { print('Hello, Dart!'); }
4. Compile and Run Dart Code:
   • To execute a Dart application, open your terminal, navigate to your project folder, and run the following command: dart run main.dart
5. Developing Flutter Applications with Dart:
   • If you are using Dart with Flutter, the steps would include creating Flutter widgets, defining state management, and handling user input. Flutter provides its own set of tools for running the application in a simulator or on an actual device.
6. Debugging and Testing:
   • Dart provides debugging tools through IDEs like Visual Studio Code or Android Studio, allowing developers to set breakpoints, inspect variables, and troubleshoot code. The Dart testing framework allows developers to write unit tests to verify the correctness of their applications.
7. Building for Production:
   • Once your Dart app is ready, you can compile it into an optimized format (AOT for mobile or Dart-to-JavaScript for web) to deploy the app to users.

Step-by-Step Getting Started Guide for Dart

Here’s a simple guide to getting started with Dart:

1. Install Dart SDK:
   • Download and install the Dart SDK from the official website: dart.dev/get-dart.
2. Create a Dart Project:
   • Open your terminal or command prompt and create a new directory for your project: mkdir dart_project cd dart_project
3. Write Your First Dart Program:
   • Create a Dart file, e.g., main.dart, and write a simple “Hello World” program: void main() { print('Hello, Dart!'); }
4. Run the Dart Code:
   • Run your Dart program using the dart command: dart run main.dart
5. Explore Dart Features:
   • Try experimenting with other Dart features like classes, async/await, and working with lists or maps. Here’s an example of a class in Dart: class Person { String name; int age; Person(this.name, this.age); void greet() { print('Hello, my name is $name and I am $age years old.'); } } void main() { var person = Person('John', 30); person.greet(); }
6. Build and Run More Complex Projects:
   • Once you are comfortable with basic Dart syntax, you can start exploring more advanced topics like Flutter for mobile development or writing web applications that compile Dart to JavaScript.

The post Exploring Dart: Use Cases, Workflow, and Getting Started Guide appeared first on scmGalaxy.

What is Flutter?

Flutter is an open-source framework developed by Google for building natively compiled, multi-platform applications from a single codebase. Initially released in 2017, Flutter allows developers to create high-performance apps for mobile (iOS and Android), web, desktop, and embedded devices with a single codebase.

Flutter uses the Dart programming language, also developed by Google, to build applications. Unlike other cross-platform frameworks that rely on a web view or use native components, Flutter compiles to native ARM code for mobile devices, ensuring high performance and smooth animations.

Key features of Flutter include:

• Hot Reload: A feature that allows developers to instantly see the changes made to the code in real-time, making development faster and more efficient.
• Widgets: Everything in Flutter is a widget, including layout elements, buttons, and even the entire app. Flutter provides an extensive collection of customizable widgets.
• Native Performance: Flutter compiles to native code, which provides high performance and ensures that apps run smoothly across different platforms.
• Cross-Platform Development: Write the code once and deploy it on multiple platforms, including Android, iOS, web, and desktop.

What are the Major Use Cases of Flutter?

Flutter is widely used across different industries and for various applications due to its versatility, fast development cycle, and cross-platform capabilities. Some of the major use cases of Flutter include:

1. Mobile Application Development

Flutter is primarily used for building mobile applications for both iOS and Android with a single codebase. This significantly reduces development time and cost compared to traditional native app development.

Example: Mobile apps for e-commerce, social media platforms, and news outlets can be developed in Flutter, offering native performance and UI consistency across both platforms.

2. Web Development

With the introduction of Flutter for the web, developers can now use the same codebase to build web applications. This makes Flutter a strong candidate for developing responsive web apps that run smoothly on both mobile and desktop web browsers.

Example: Building a blog, e-commerce site, or enterprise dashboard with consistent performance across devices.

3. Desktop Applications

Flutter also supports desktop application development for Windows, macOS, and Linux. This means developers can use Flutter to build cross-platform desktop apps without needing to write separate code for each operating system.

Example: Desktop applications like productivity tools, data analysis platforms, or cross-platform games can be developed in Flutter.

4. Embedded Devices

Flutter can be used to develop applications for embedded devices, such as IoT devices or smart TVs, that require a rich and responsive UI.

Example: Building user interfaces for embedded systems like smart home devices, kiosks, or point-of-sale systems.

5. Prototyping and MVP Development

Flutter is an excellent tool for quickly building prototypes or minimum viable products (MVPs). Its fast development cycle and hot reload feature make it ideal for testing ideas and getting feedback before committing to full-scale app development.

Example: A startup or product team can quickly create a prototype of a new app and test it with real users before investing more resources.

6. Gaming

Flutter can also be used for simple 2D game development, especially games that require smooth animations and a native feel.

Example: Simple mobile games or apps with game-like functionality, such as interactive educational tools, can be developed in Flutter.

How Flutter Works: Architecture Overview

Flutter’s architecture is designed to provide high performance, flexibility, and ease of use. Its key components work together to deliver seamless app development experiences. Below is an overview of how Flutter works and its core architecture:

1. Dart Programming Language

Flutter uses Dart, an object-oriented programming language, as its primary language. Dart is optimized for client-side development and offers features like Just-In-Time (JIT) compilation for fast development and Ahead-Of-Time (AOT) compilation for performance optimization in production.

• JIT: During development, JIT compilation allows for hot reload, meaning developers can see changes in real-time without restarting the app.
• AOT: When the app is ready for production, Flutter uses AOT compilation to generate optimized native code, ensuring faster startup times and smooth performance.

2. Widgets

In Flutter, everything is a widget. Widgets form the core building blocks of the user interface, and Flutter provides a wide range of pre-built widgets that are customizable. The widget tree structure in Flutter allows for building UIs with complex and nested layouts.

• Stateless Widgets: These widgets do not store any state and are typically used for UI elements that remain the same during the app’s lifecycle (e.g., text labels, buttons).
• Stateful Widgets: These widgets maintain their state over time and are used for interactive elements (e.g., text input fields, checkboxes).

Example:

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

3. Flutter Engine

The Flutter engine is responsible for rendering the UI and handling low-level tasks like drawing pixels to the screen, managing input events, and performing animations. The engine is written in C++ and interfaces with the native operating system through platform channels.

• Skia Graphics Library: The Flutter engine uses Skia, a 2D graphics library, for rendering the UI. Skia is highly optimized for high-performance graphics, enabling Flutter to render smooth and complex UI components.

4. Flutter Framework

The Flutter framework sits on top of the engine and provides the necessary tools and libraries for building applications. This framework includes packages for:

• Material Design: A library for implementing Google’s Material Design principles.
• Cupertino Widgets: A library for implementing iOS-style widgets.

5. Platform Channels

Flutter uses platform channels to communicate with the underlying platform (iOS/Android). This allows Flutter apps to call native code when needed, enabling access to platform-specific features such as camera, GPS, sensors, and storage.

Example: To access the device’s camera, a Flutter app can use platform channels to call the native camera API on iOS or Android.

Basic Workflow of Flutter

The basic workflow of developing with Flutter involves several stages, which can be summarized as follows:

1. Project Setup: Create a new Flutter project using the flutter create command. This generates a default app structure with essential files for building your application.
2. Design UI Using Widgets: Use Flutter’s built-in widgets (Stateless and Stateful) to create your app’s UI. The widget tree allows you to structure and organize your UI elements, making it easy to customize.
3. Implement Logic and State Management: Add logic to your app by defining functions and managing the app’s state. Flutter provides various state management solutions, including setState, Provider, Riverpod, and BLoC.
4. Testing: Flutter provides a rich set of testing tools, including unit tests, widget tests, and integration tests. You can test your app’s functionality and ensure that everything works as expected before deploying it.
5. Build and Deploy: Once the app is developed and tested, you can build the app for different platforms (Android, iOS, web, desktop) using the flutter build command. Then, deploy the app to the relevant app stores or hosting platforms.

Step-by-Step Guide to Getting Started with Flutter

Here’s a step-by-step guide for beginners to get started with Flutter:

Step 1: Install Flutter

• First, download and install Flutter by visiting the official Flutter website (https://flutter.dev/docs/get-started/install).
• Follow the platform-specific instructions to install Flutter on Windows, macOS, or Linux.
• Ensure that Android Studio (for Android development) or Xcode (for iOS development) is installed.

Step 2: Create a New Flutter Project

Open your terminal or command prompt and run the following command:

flutter create my_app

This will generate a new Flutter project named my_app. Once created, navigate to the project directory:

cd my_app

Step 3: Run the Flutter App

Make sure your emulator (Android or iOS) or physical device is running. Then, start the app by running:

flutter run

Step 4: Build the UI

Open the lib/main.dart file, where you will define the app’s UI using widgets. For example, you can update the default app to display a simple “Hello, Flutter!” message:

void main() {
  runApp(MyApp());
}

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

Step 5: Add Interactivity

Add interactivity to your app by using Stateful widgets and adding event handlers, such as button presses or text input.

Example of a button press:

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Flutter Counter')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('Button pressed $_counter times'),
            ElevatedButton(
              onPressed: _incrementCounter,
              child: Text('Increment'),
            ),
          ],
        ),
      ),
    );
  }
}

Step 6: Test and Debug

Test your app by using Flutter’s hot reload feature, which allows you to instantly view changes in your app as you modify the code.

Step 7: Build and Deploy

Once you are satisfied with the app, use flutter build to prepare the app for deployment to Android, iOS, or web platforms.

The post Understanding Flutter: Architecture, Use Cases, and Getting Started Guide appeared first on scmGalaxy.

I’m showing an AlertDialog on my App, but when I click on no/cancel then AlertDialog doesn’t dismiss, it keep popping the route where I came from. I’ve used Navigator.of(context).pop(); and Navigator.pop(context, false); but both are not working.

Solution

To Dismiss an AlertDialog Navigator.of(context).pop(); works but in my case below code worked.

Navigator.of(context, rootNavigator: true).pop('dialog');

That’s All.

Thanks for reading.

Keep Coding.

The post Flutter : How to dismiss an AlertDialog on Button? appeared first on scmGalaxy.

In your android/app/build.gradle, update the following:

android {
    // ...
    defaultConfig {
        // ...
        minSdkVersion 16
    }
}

into:

android {
    // ...
    defaultConfig {
        // ...
        minSdkVersion 23
    }
}

Note: You need to use minSdkVersion 23 when using firebase in flutter.

That’s All.

Thanks for reading.

Keep Coding.

The post [SOLVED] Flutter : firebase_core_web not found. Please update settings.gradle. appeared first on scmGalaxy.

1. Delete .idea folder.
2. Create a new temporary Flutter project with the same name.
3. Copy from the project to your existing project these 2 missing files:

• [project_name].iml
• android/[project_name]_android.iml

4. Open Android Studio and the problem should be gone.

To avoid it in the future, make sure .iml files are not excluded in the gitignore. There is a Github issue on this topic.

The post [SOLVED] Flutter: Not showing “Open for editing in Android Studio” appeared first on scmGalaxy.

After upgrading firebase_auth to latest version (i.e., ^1.2.0), it says update intl to ^0.17.0. When i updated intl, I’m getting errors when I try to run flutter pub get.

C:\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_messaging-9.1.4\android\src\main\java\io\flutter\plugins\firebase\messaging\FlutterFirebaseMessagingPlugin.java:20: error: cannot find symbol
    import com.google.firebase.iid.FirebaseInstanceId;
                                  ^
      symbol:   class FirebaseInstanceId
      location: package com.google.firebase.iid
    C:\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_messaging-9.1.4\android\src\main\java\io\flutter\plugins\firebase\messaging\FlutterFirebaseMessagingPlugin.java:21: error: cannot find symbol
    import com.google.firebase.iid.Metadata;
                                  ^
      symbol:   class Metadata
      location: package com.google.firebase.iid
    C:\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_messaging-9.1.4\android\src\main\java\io\flutter\plugins\firebase\messaging\FlutterFirebaseMessagingPlugin.java:152: error: cannot find symbol
                      : Metadata.getDefaultSenderId(FirebaseApp.getInstance());
                        ^
      symbol:   variable Metadata
      location: class FlutterFirebaseMessagingPlugin
    C:\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_messaging-9.1.4\android\src\main\java\io\flutter\plugins\firebase\messaging\FlutterFirebaseMessagingPlugin.java:153: error: cannot find symbol
              FirebaseInstanceId.getInstance().deleteToken(senderId, "*");
              ^
      symbol:   variable FirebaseInstanceId
      location: class FlutterFirebaseMessagingPlugin
    C:\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_messaging-9.1.4\android\src\main\java\io\flutter\plugins\firebase\messaging\FlutterFirebaseMessagingPlugin.java:165: error: cannot find symbol
                      : Metadata.getDefaultSenderId(FirebaseApp.getInstance());
                        ^
      symbol:   variable Metadata
      location: class FlutterFirebaseMessagingPlugin
    C:\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_messaging-9.1.4\android\src\main\java\io\flutter\plugins\firebase\messaging\FlutterFirebaseMessagingPlugin.java:166: error: cannot find symbol
              String token = FirebaseInstanceId.getInstance().getToken(senderId, "*");
                             ^
      symbol:   variable FirebaseInstanceId
      location: class FlutterFirebaseMessagingPlugin

Solution

Update firebase_messaging to latest one (Currently i.e., firebase_messaging: ^10.0.0), and call flutter pub get.

That’s it.

Thanks for Reading.

Keep Coding.

The post [SOLVED] FlutterFirebaseMessagingPlugin.java – Build fails with Exception “error: cannot find symbol” appeared first on scmGalaxy.

The android studio while running throws this error and stop the build

A:\flutter.pub-cache\hosted\pub.dartlang.org\webview_flutter-2.0.6\android\src\main\java\io\flutter\plugins\webviewflutter\InputAwareWebView.java:31: error: cannot find symbol private ThreadedInputConnectionProxyAdapterView proxyAdapterView; ^ symbol: class ThreadedInputConnectionProxyAdapterView location: class InputAwareWebView

A:\flutter.pub-cache\hosted\pub.dartlang.org\webview_flutter-2.0.6\android\src\main\java\io\flutter\plugins\webviewflutter\InputAwareWebView.java:112: error: cannot find symbol new ThreadedInputConnectionProxyAdapterView( ^ symbol: class ThreadedInputConnectionProxyAdapterView location: class InputAwareWebView Note: Some input files use or override a deprecated API. Note: Recompile with -Xlint:deprecation for details. 2 errors

FAILURE: Build failed with an exception.

Solution

ThreadedInputConnectionProxyAdapterView has wrong extension .jav just change it to .java until the flutter team release the fix.

Its Located to :- C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\webview_flutter-2.0.6\android\src\main\java\io\flutter\plugins\webviewflutter

That’s All.

Thanks for Reading.

Keep Coding.

The post [SOLVED] Flutter Webview throws Compiling Error. appeared first on scmGalaxy.

I’m using flutter_recaptcha_v2: ^0.1.0. Now, I am trying to run it using flutter run, however, it will not start because of the following error:

Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

- package:flutter_recaptcha_v2
- package:webview_flutter
- package:http
- package:http_parser

For solutions, see https://dart.dev/go/unsound-null-safety
FAILURE: Build failed with an exception.

* Where:
Script 'C:\src\flutter\packages\flutter_tools\gradle\flutter.gradle' line: 1035

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command 'C:\src\flutter\bin\flutter.bat'' finished with non-zero exit value 1

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 21s
Exception: Gradle task assembleDebug failed with exit code 1
Exited (sigterm)

Solution

If you want run your project with --no-sound-null-safety so now you add this line your main.dart file in top(first line) with comment..

// @dart=2.9

then run your project.

Thanks for reading.

Keep Coding.

The post [SOLVED] Flutter : Cannot run with sound null safety, because the following dependencies don’t support null safety appeared first on scmGalaxy.

I’m Calling An API and getting response in Variable Data ($data). When data is coming then there is no Error but when I’m getting null as response then getting this error Unhandled Exception: NoSuchMethodError: The getter ‘isEmpty’ was called on null.

When I am using the below code then it is throwing me an error:

Solution

That is because $data returns null, So I’ve Used

if(data?.isEmpty ?? true)

? prevents an error if the previous part of the expression results in null and ?? true results in true if the previous part of the expression is null and therefore treats == null and isEmpty the same for the if(...) check.

Now My Code is working Fine.

Thanks for reading.

Keep Coding.

The post [SOLVED] Flutter : NoSuchMethodError: The getter ‘isEmpty’ was called on null. appeared first on scmGalaxy.

I’ve connected my flutter app to firebase by adding SHA1 key ( How to Get SHA-1 key in Android Studio for Firebase. ) and package name in firebase console, and also downloaded and provided google-service.json in my flutter app at android/app. But when i run app its Showing an error that i’ve not provided google-service.json file in my app. The Error Says –

E/flutter (15568): [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: [core/not-initialized] Firebase has not been correctly initialized. Have you added the "google-services.json" file to the project? 
E/flutter (15568): 

Solution

After hours of struggle, I am able to figure out the solution.

1. First, add the ‘google-services.json‘ plugin as a dependency inside of the android/build.gradle file:

 buildscript {
      dependencies {
        // ... other dependencies
        classpath 'com.google.gms:google-services:4.3.3'
      }
    }

2. Lastly, execute the plugin by adding the following underneath the line apply plugin:
add after ‘com.android.application’, within the /android/app/build.gradle file:

apply plugin: 'com.google.gms.google-services'

That’s All.

Thanks for Reading.

Keep Coding.

The post [Solved] Flutter : [core/not-initialized] Firebase has not been correctly initialized. Have you added the “google-services.json” file to the project? appeared first on scmGalaxy.