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Platforms Community Try Dart Get Dart Docs Samples & tutorials Language samples Codelabs List of Dart codelabs Language cheatsheet Iterable collections Asynchronous programming Tutorials Language Effective Dart Overview Style Documentation Usage Design Extension methods Specification Tour Type system Core libraries Overview Tour Articles Intro to dart:io Creating streams Packages How to use packages Commonly used packages Creating packages Publishing packages Package reference Dependencies Glossary Package layout conventions Pub environment variables Pubspec file Troubleshooting pub Verified publishers Versioning Development Futures, async, await Interoperability C interop JavaScript interop JSON Streams Mobile apps Command-line & server apps Overview Get started Write command-line apps Write HTTP clients & servers Libraries and packages Web apps Overview Get started Fetch data dynamically Low-level web programming Connect Dart & HTML Add elements to the DOM Remove DOM elements Deployment Libraries and packages Tools & techniques Overview Editors & debuggers IntelliJ & Android Studio VS Code Dart DevTools DartPad Command-line tools Dart SDK Overview dart (Dart VM) dart2js (prod JS) dart2native dartanalyzer dartaotruntime dartdevc (dev JS) dartdoc dartfmt pub Other command-line tools build_runner webdev Managing source code Formatting code What not to commit Static analysis Customizing static analysis Fixing common type problems Testing & optimization Testing Debugging web apps Resources Overview Books DartPad in tutorials: best practices Code of conduct FAQ History Migrating to Dart 2 Migrating web apps to Dart 2 Obsolete pub features Videos Related sites API reference Blog DartPad (online editor) Flutter Package site Dart is a client-optimized language for fast apps on any platform play_circle_filled Watch video Optimized for UI Develop with a programming language specialized around the needs of user interface creation Productive development Make changes iteratively: use hot reload to see the result instantly in your running app Fast on all platforms Compile to ARM & x64 machine code for mobile, desktop, and backend. Or compile to JavaScript for the web Optimized for UI Mature and complete async-await for user interfaces containing event-driven code, paired with isolate-based concurrency A programming language optimized for building user interfaces with features such as the spread operator for expanding collections, and collection if for customizing UI for each platform A programming language that is easy to learn, with a familiar syntax Productive Development Make changes to your source code iteratively, using hot reload to instantly see the effect in the running app Write code using a flexible type system with rich static analysis and powerful, configurable tooling Do profiling , logging , and debugging with your code editor of choice Fast on all platforms AOT-compile apps to native machine code for instant startup Target the web with complete, mature, fast compilers for JavaScript Run backend code supporting your app, written using a single programming language Optimized for UI Mature and complete async-await for user interfaces containing event-driven code, paired with isolate-based concurrency A programming language optimized for building user interfaces with features such as the spread operator for expanding collections, and collection if for customizing UI for each platform A programming language that is easy to learn, with a familiar syntax Productive development Make changes to your source code iteratively, using hot reload to instantly see the effect in the running app Write code using a flexible type system with rich static analysis and powerful, configurable tooling Do profiling , logging , and debugging with your code editor of choice Fast on all platforms AOT-compile apps to native machine code for instant startup Target the web with complete, mature, fast compilers for JavaScript Run backend code supporting your app, written using a single programming language Try Dart in your browser Want more practice? Try a codelab . Or download Dart . Hello, World! main () { print ( ’Hello, World!’ ); } Functions // A function declaration. int timesTwo ( int x ) { return x * 2 ; } // Arrow syntax is shorthand for `{ return expr; }`. int timesFour ( int x ) = timesTwo ( timesTwo ( x )); // Functions are objects. int runTwice ( int x , Function f ) { for ( var i = 0 ; i2 ; i ++) { x = f ( x ); } return x ; } main () { print ( "4 times two is ${timesTwo(4)} " ); print ( "4 times four is ${timesFour(4)} " ); print ( "2 x 2 x 2 is ${runTwice(2, timesTwo)} " ); } Control flow bool isEven ( int x ) { // An if-else statement. if ( x % 2 == 0 ) { return true ; } else { return false ; } } ListintgetEvenNumbers ( Iterableintnumbers ) { var evenNumbers =int []; // A for-in loop. for ( var i in numbers ) { // A single-line if statement. if ( isEven ( i )) evenNumbers . add ( i ); } return evenNumbers ; } main () { var numbers = List . generate ( 10 , ( i ) = i ); print ( getEvenNumbers ( numbers )); } Strings main () { print ( ’a single quoted string’ ); print ( "a double quoted string" ); // Strings can be combined with the + operator. print ( ’cat’ + ’dog’ ); // Triple quotes define a multi-line string. print ( ’’’triple quoted strings are for multiple lines’’’ ); // Dart supports string interpolation. const pi = 3.14 ; print ( ’pi is $pi ’ ); print ( ’tau is ${2 * pi} ’ ); } Collection literals // A list literal. var lostNumbers = [ 4 , 8 , 15 , 16 , 23 , 42 ]; // A map literal. var nobleGases = { ’He’ : ’Helium’ , ’Ne’ : ’Neon’ , ’Ar’ : ’Argon’ , }; // A set literal. var frogs = { ’Tree’ , ’Poison dart’ , ’Glass’ , }; main () { print ( lostNumbers . last ); print ( nobleGases [ ’Ne’ ]); print ( frogs . difference ({ ’Poison dart’ })); } Classes // Abstract classes can’t be instantiated. abstract class Item { use (); } // Classes can implement other classes. class ChestTimplements Item { ListTcontents ; // Constructors can assign arguments to instance variables using `this`. Chest ( this . contents ); use () = print ( " $this has ${contents.length} items." ); } class Sword implements Item { int damage = 5 ; use () = print ( " $this dealt $damage damage." ); } // Classes can extend other classes. class DiamondSword extends Sword { int damage = 50 ; } main () { // The ’new’ keyword is optional. var chest = ChestItem ([ DiamondSword (), Sword (), ]); chest . use (); for ( var item in chest . contents ) { item . use (); } } Compute π import ’dart:math’ show Random ; main () async { print ( ’Compute π using the Monte Carlo method.’ ); await for ( var estimate in computePi (). take ( 100 )) { print ( ’π ≅ $estimate ’ ); } } /// Generates a stream of increasingly accurate estimates of π. StreamdoublecomputePi ({ int batch = 100000 }) async * { var total = 0 ; var count = 0 ; while ( true ) { var points = generateRandom (). take ( batch ); var inside = points . where (( p ) = p . isInsideUnitCircle ); total += batch ; count += inside . length ; var ratio = count / total ; // Area of a circle is A = π⋅r², therefore π = A/r². // So, when given random points with x ∈ 0,1, // y ∈ 0,1, the ratio of those inside a unit circle // should approach π / 4. Therefore, the value of π // should be: yield ratio * 4 ; } } IterablePointgenerateRandom ([ int seed ]) sync * { final random = Random ( seed ); while ( true ) { yield Point ( random . nextDouble (), random . nextDouble ()); } } class Point { final double x , y ; const Point ( this . x , this . y ); bool get isInsideUnitCircle = x * x + y * y = 1 ; }Terms Security Privacy Site CC BY...