dart學習（繼承）

1、使用關鍵字extends繼承一個類

2、子類會繼承父類課件的屬性和方法，不會繼承構造方法

3、子類能夠複寫父類的方法、getter和setter

4、單繼承、多態性

1）person.dart

class Person {
  String name;
  int age;
  String _birthday;

  bool get isAdult => age > 18;

  void run() {
    print("Person run...");
  }

}

2）class_extends.dart

import 'person.dart';

void main() {
  var student = new Student();
  student.study();

  student.name = "Tom";
  student.age = 16;
  student.isAdult;

  print(student.isAdult);

  student.run();
}

class Student extends Person {
  void study() {
    print("Student study...");
  }

  @override
  bool get isAdult => age > 15;

  @override
  void run() {
    print("Student run...");
  }
}

運行結果：

Student study...
true
Student run...

 

向上轉型

 Person person = new Student();
  if (person is Student) {
    person.study();
  }