What is the difference between var and dynamic and final in dart?| Flutter By Example

This tutorial shows you the usage of var, dynamic and final keywords in the dart, see the between var vs dynamic vs final in the dart.

#Difference between var, dynamic, and final in Dart

These three keywords are used for variable declaration in Dart. Let’s explore their differences.

• var keyword The var keyword is utilized to declare variables and assign multiple values. Here are its key features:
  • Variables declared with var can only change their value.
  • The datatype of a variable declared with var cannot be changed.

void main() {
  var variable = 123; // declared an int variable with a value
  print(variable.runtimeType); // int

  variable = 243; // can change its value
  variable = "abc"; // compilation error when attempting to change its type
}

• dynamic keyword

The dynamic keyword allows assigning dynamic types at runtime.

Variables declared with dynamic can change both their value and datatype.

Here’s what you need to know about it:

• variable declared with dynamic change its value
• also, datatype can be changed

void main() {
  dynamic variable = 123; // declared an int variable with a value
  print(variable.runtimeType); // int

  variable = 243; // can change its value
  variable = "abc"; // can change its type, assigned with a string
  print(variable.runtimeType); // String
}

• final keyword

The final keyword restricts variable assignment to only once, making it akin to compile-time constants. Its features include

• Variables declared with final cannot change their value after assignment.
• The datatype of a final variable remains constant.

void main() {
  final variable = 123; // declared an int variable with a value
  print(variable.runtimeType); // int

  variable = 243; // compilation error, variable cannot be changed
  variable = "abc"; // compilation error when attempting to change its type
}

#var vs dynamic vs final keywords in dart

Let’s see the comparison between var vs dynamic vs final keywords in dart