5.8. Introduction to Object Oriented Programming in Dart: Static Methods

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Object-oriented programming (OOP) is a programming paradigm that uses "objects" - instances of classes - to structure an application. Dart, the programming language used in Flutter, is an object-oriented language. OOP is a fundamental concept for understanding and working with Flutter effectively. In this section, we'll focus on one aspect of OOP in Dart - static methods.

Static methods, also known as class methods, are functions that belong to a class rather than to an instance of a class. They are called "static" because they exist in the class itself, not in instances of the class. This means you can call a static method without creating an instance of a class.

To declare a static method in Dart, you use the 'static' keyword. For example, consider the following 'MathHelper' class:

class MathHelper {
  static int add(int a, int b) {
    return a + b;
  }
}

In this example, 'add' is a static method that accepts two integers and returns their sum. You can call this method directly in the 'MathHelper' class, without creating an instance of it:

int sum = MathHelper.add(5, 3); // sum is 8

Static methods are useful when you have functionality that doesn't depend on the state of a class instance. In the example above, adding two numbers is a pure operation that does not depend on any states. So it makes sense to make the 'add' method a static method.

However, static methods have limitations. They cannot access non-static properties or methods of your class. This is because they are not associated with a specific instance of the class. For example, the following code would result in an error:

class MathHelper {
  int x;

  static int addX(int a) {
    return a + x; // Error: 'x' cannot be accessed from a static method.
  }
}

In short, static methods in Dart are functions that belong to a class rather than an instance of a class. They are useful when you have functionality that doesn't depend on the state of a class instance. However, they cannot access non-static properties or methods of your class.

Understanding how and when to use static methods is an important part of learning Dart and Flutter. Throughout this course, you will have many opportunities to practice creating and using static methods. Remember, practice is the key to becoming proficient in any programming skill!

In the next section, we'll explore another important concept in object-oriented programming in Dart - class inheritance. Stay tuned!

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655.9. Introduction to object-oriented programming in Dart: Constructors