Dart Advanced Features: Functions, Classes, Objects, Error Handling, and Collections

In this unit, we will delve deeper into the advanced features of Dart, including functions, classes, objects, error handling, and collections. These features are fundamental to writing efficient and effective Dart code.

Functions

Functions in Dart are objects, meaning they can be assigned to variables or passed as arguments to other functions. You can define a function with the void keyword for functions that don't return a value, or with the type of the value that they return. Dart also supports anonymous functions and arrow syntax for short functions.

void greet(String name) {
  print('Hello, $name!');
}

var greetAgain = (String name) => print('Hello, $name!');

Classes and Objects

Dart is an object-oriented language, and classes and objects are at the heart of Dart programming. A class is a blueprint for creating objects, and an object is an instance of a class. Dart supports inheritance, allowing you to create a new class that inherits the properties and methods of an existing class. It also supports polymorphism, allowing you to use a child class as if it were a parent class.

class Animal {
  void eat() {
    print('Eating...');
  }
}

class Dog extends Animal {
  void bark() {
    print('Barking...');
  }
}

var dog = Dog();
dog.eat();  // Inherited from Animal
dog.bark(); // Defined in Dog

Error Handling and Exceptions

Dart provides robust error handling capabilities with try-catch-finally blocks. When an error occurs, Dart "throws" an exception, which you can "catch" and handle. If you don't catch the exception, the Dart runtime catches it and terminates the program.

try {
  var result = 100 ~/ 0; // Throws an exception
} catch (e) {
  print('Caught an exception: $e');
} finally {
  print('This is always executed');
}

Working with Collections

Dart provides several collection types, such as List, Set, and Map. A List is an ordered group of items, a Set is an unordered group of unique items, and a Map is an unordered group of key-value pairs.

var list = [1, 2, 3]; // List
var set = {1, 2, 3}; // Set
var map = {'one': 1, 'two': 2, 'three': 3}; // Map

In conclusion, understanding these advanced features of Dart will enable you to write more complex and powerful Dart programs. In the next unit, we will explore how to use and create packages in Dart.