Classes and Instances

Classes and Instances

In this lesson — part of Objects and Classes — you'll learn classes and instances in Dart and why it matters in real work.

Why it matters

Classes bundle data and behavior together — the core of object-oriented design.

Key ideas

• Classes and instances
• Fields and methods
• Constructors
• Encapsulation

In practice

Here's how it looks in idiomatic Dart:

class Counter {
  int value = 0;             // field
  void increment() => value++; // method
}

void main() {
  final c = Counter();       // no `new` keyword needed
  c.increment();
  print(c.value);            // 1
}

Dart note: Dart classes need no new keyword to instantiate, and every field automatically gets implicit getters/setters.

Try it yourself

Exercise: In Dart, write a Bank Account class with deposit and withdraw methods.

Recap

You now understand classes and instances and can apply it in Dart. Mark this lesson complete and continue to the next one.