Introduction to Dart Programming

• Dart is a client-optimized, open-source programming language developed by Google.
• It is used to build web, server, desktop, and mobile applications.
• Dart is an object-oriented, class-defined, garbage-collected language with C-style syntax.
• Dart supports concepts like interfaces, mixins, abstract classes, generics, and type inference.
• Dart compiles to native code or JavaScript.

Key Features

• Null safety helps prevent null reference errors at runtime.
• Asynchronous programming supports async/await keywords for writing non-blocking code.
• A rich set of built-in libraries provides core functionalities for various tasks.
• Strong typing supports static type checking to catch errors early.
• Ahead-of-time (AOT) and Just-in-time (JIT) compilation enables fast startup and execution.
• Hot reload allows seeing changes in the code instantly during development.

Basic Syntax

• Dart programs start with a main() function.
• Statements end with a semicolon (;).
• Comments can be single-line (//) or multi-line (/* ... */).
• Variables are declared using var, final, or a specific type.
• Data types include int, double, String, bool, List, and Map.

Variables

• var declares variables without specifying the type explicitly; the type is inferred.
• dynamic allows variables to hold values of any type, and type checking is done at runtime.
• Object is similar to dynamic but treats everything as an object.
• final declares a variable that can only be set once.
• const declares a compile-time constant.

Data Types

• Numbers:
  • int represents integer values.
  • double represents floating-point values.
• Strings:
  • String represents a sequence of characters.
• Booleans:
  • bool represents true or false values.
• Lists (Arrays):
  • List represents an ordered collection of items.
• Maps (Dictionaries):
  • Map represents a collection of key-value pairs.

Operators

• Arithmetic operators: +, -, *, /, %
• Relational operators: ==, !=, >, <, >=, <=
• Logical operators: &&, ||, !
• Assignment operators: =, +=, -=, *=, /=, %=
• Bitwise operators: &, |, ^, ~, <<, >>

Control Flow

• if-else statements are used for conditional execution of code.
• for loops are used for iterating over a sequence of values.
• while loops are used for executing a block of code repeatedly as long as a condition is true.
• do-while loops are similar to while loops, but the code block is executed at least once.
• switch-case statements select one of several code blocks to execute based on the value of a variable.
• break terminates the current loop or switch statement.
• continue skips the rest of the current iteration of a loop and continues with the next iteration.

Functions

• Functions are declared using the returnType functionName(parameters) { ... } syntax.
• If no return type is specified, the function returns null.
• Anonymous functions (lambdas) can be created using the (parameters) => expression syntax.
• Functions can have optional positional or named parameters.
• Default values can be provided for optional parameters.

Classes and Objects

• Classes are defined using the class keyword.
• Objects are instances of classes.
• Classes can have constructors, methods, and properties.
• Constructors are special methods used to create and initialize objects.
• Inheritance is supported using the extends keyword.
• Abstract classes cannot be instantiated and are used as a base for other classes.
• Interfaces define a contract that classes can implement using the implements keyword.
• Mixins allow code reuse in multiple classes using the with keyword.

Collections

• Lists are ordered collections of items, and can be created using List or [].
• Sets are unordered collections of unique items, and can be created using Set or {}.
• Maps are collections of key-value pairs, and can be created using Map or {}.
• Common operations: Adding, removing, iterating, and searching.

Exception Handling

• Exceptions are used to handle errors and unexpected events.
• Exceptions can be thrown using the throw keyword.
• Exceptions can be caught using the try-catch block.
• The finally block is used to execute code regardless of whether an exception was thrown or caught.

Asynchronous Programming

• Future represents a value that will be available sometime in the future.
• async and await are keywords used to write asynchronous code in a synchronous style.
• Stream represents a sequence of asynchronous events.

Libraries and Packages

• Dart has a rich ecosystem of libraries and packages.
• Libraries are collections of code that can be imported and used in other programs.
• Packages are collections of libraries and assets that can be distributed and reused.
• Packages are managed using the pub package manager.
• Common libraries include dart:core, dart:io, dart:html, and dart:math.

Null Safety

• Dart has sound null safety, meaning that the compiler can guarantee that a variable will never be null unless it is explicitly allowed.
• Nullable types are denoted with a ? suffix (e.g., String?).
• The ! operator asserts that a nullable value is not null.
• Null-aware operators such as ?., ??, and ??= handle nullable values safely.

Key differences from JavaScript

• Dart is statically typed, while JavaScript is dynamically typed.
• Dart supports AOT compilation, resulting in faster startup times compared to JavaScript.
• Dart has a more comprehensive standard library than JavaScript.
• Dart's syntax is similar to Java and C#, whereas JavaScript has its unique syntax.
• Dart includes strong support for isolates, enabling true parallelism, which differs from JavaScript's single-threaded concurrency model.
• Dart handles optional parameters more flexibly than JavaScript.
• Dart relies on classes for almost all object composition, while JavaScript's prototype-based inheritance is more flexible but can be less structured.