How are immutable objects implemented and used in Dart?

In Dart, immutable objects are created using the keywords final or const.

• final means that the variable can be assigned only once, but the object it refers to can be mutable.
• const creates a constant object that is compiled at compile-time and cannot be changed.

To create fully immutable classes, all fields are usually declared as final and no setters are provided. This guarantees that the object will not change after creation.

Example:

class Point {
  final int x;
  final int y;

  const Point(this.x, this.y);
}

void main() {
  const p = Point(1, 2);
  // p.x = 3; // Error: cannot modify final field
}

This approach is useful for increasing code safety, simplifying debugging, and working with streams, as immutable objects do not require synchronization.