Introduction

The variables and methods of a class are shared across all instances of the class. They are not called on any specific object instance of the class.

In the Dart language, there are two ways to implement such variables and methods.

1. Using the static keyword
2. Without the static keyword

The class-level variable(s) is useful to declare constants and implement a class-wide state. Generally, utility classes use class variables and methods to provide quick and easy access to methods and constants.

With the static keyword

The static keyword is used to declare class level variables and methods.

The class methods can be called from other classes using the class names they are defined in.

Let’s take an example of a string utility class called StringUtils. This class contains a convenience method called reverse(String str) to reverse the given string. This utility class has a constant dart which is inferred to contain a string value of “oh dart.”

class StringUtils {
  static const dart = "oh dart";

  static String reverse(String str) {
    return String.fromCharCodes(str.runes.toList().reversed);
  }
}

Note: If you are interested in learning about runes used in code above to reverse the string, check out my article on Runes.

Using a Class variable

Let’s reiterate the facts about class variables:

• Static variables are not initialized until they are used.
• They are useful for representing class state and constants.
• Constants names are declared using the lowerCamelCase convention.
• The class-level variable can be accessed using the class name.

In the code below, StringUtils is needed to access constant dart.