dart Quick Start Tutorial (7.3)

# 7.4 disengagement class file as a single file to create a new, separate storage class, for example: Person class file detached to person.dart

class Person {
  final String name;
  final num age;
  final String gender;
  const Person(this.name, this.age, this.gender);
  
}

The introduction of the Person class

import './person.dart';

void main() {
  var p = new Person("xiaoqiang", 18, "男");
  print(p.gender);
}

Value of # 7.5. Initialization list initialization list is a series of initialization operation performed before the body construction method, commonly used in the final set of variables



void main() {
  // 注意：new关键字可以省略
  // var p = new Person("xiaoqiang", 12, "男");
  // print(p.name);
  // 创建对象的时候，可以使用fn构造方法
  var p2 = new Person.fn("xiaohong", 12);
  
}

class Person {
  String name;
  num age;
  final String gender;
  Person(this.name, this.age, this.gender){
   
    print(this.name);
    print(this.age);
    print(this.gender);
  }
  // 在构造方法后面加冒号来设置初始化列表，每个初始化变量之间用逗号隔开
  Person.fn(name, age):gender="男", name="xiaoli"{
    print(name);
    print(age);
  }
}

# 7.6. Static members can use the static keyword to achieve class-level variables and functions, popular to say that static members can be called directly by the class name

void main() {
  print(Person.name);
  Person.showName();
}

class Person {
  static String name;
  static num age;
  static void showName () {
    name = "xiaoqiang";
    print(name);
  }
  void showAge () {
    // 非静态成员是可以直接使用静态成员
    age = 10;
    print(age);
  }
 
}

Note: static member can not access non-static member

void main() {
  print(Person.name);
  Person.showName();
  var p = new Person();
  p.showAge();
}

class Person {
  static String name;
  static num age;
  String gender = '男';
  static void showName() {
    name = "xiaoqiang";
    print(name);
    // 报错 静态方法不能访问非静态的属性
    print(gender);
  }

  void showAge() {
    // 非静态成员是可以直接使用静态成员
    age = 10;
    print(age);
  }
}

Note 2: definition of static constant need to use static const, for example: static const gender = "M", the defined constants can be accessed in a static method

# 7.7 Object member access operator condition?.

void main() {
  var p = new Person();
  // 如果p为空就不执行showName方法 如果p不为空就会执行
  p?.showName();
}

class Person {
  String name;
  static num age;
  showName() {
    print(name);
  }
}

is 和 is!

void main() {
  var p = new Person();
  if (p is Person) {
    p.showName();
  } else {
    print("不属于这个类");
  }
}

class Person {
  String name;
  static num age;
  showName() {
    print(111);
    print(name);
  }
}

Cascade operation ..

void main() {
  new Person()
    ..name = "小强"
    ..age = 20
    ..showName();
}

class Person {
  String name;
  num age;
  showName() {
    print(111);
    print(name);
  }
}

The method defined internal call # 7.8.call method as classes, then the object can be called as a method

void main() {
  var p = new Person();
  p();
  p.showName();
}

class Person {
  String name;
  num age;
  showName() {
    print(111);
    print(name);
  }

  call() {
    print('call 方法被执行了');
  }
}

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dart Quick Start Tutorial (7.3)

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