Classes
- Dart is an object-oriented language with classes and mixin-based inheritance.
- Every object is an instance of a class, and all classes descend from Object.
- Mixin-based inheritance means that although every class (except for Object) has exactly one superclass, a class body can be reused in multiple class hierarchies.
Using class members
Use a dot (.) to refer to an instance variable or method.
Use ?. instead of . to avoid an exception when the leftmost operand is null.
Getting an object’s type
To get an object’s type at runtime, you can use Object’s runtimeType property, which returns a Type object.
Extending a class
class Television {
void turnOn() {
_illuminateDisplay();
_activateIrSensor();
}
// ···
}
class SmartTelevision extends Television {
void turnOn() {
super.turnOn();
_bootNetworkInterface();
_initializeMemory();
_upgradeApps();
}
// ···
}
Use extends to create a subclass, and super to refer to the superclass.