Flutter study notes_Dart: Static members and object operators of Dart classes

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1. Static member static method in Dart class

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Static members in Dart:
1. Use the static keyword to implement class-level variables and functions
2. Static methods cannot access non-static members, and non-static methods can access static members

// class Person {
    
    
//   static String name = '张三';
//   static void show() {
    
    
//     print(name);
//   }
// }

// main(){
    
    
//   print(Person.name);
//   Person.show();  
// }






class Person {
    
    
  static String name = '张三';
  int age=20;  
  static void show() {
    
    
    print(name);
  }
  void printInfo(){
    
      /*非静态方法可以访问静态成员以及非静态成员*/
      // print(name);  //访问静态属性
      // print(this.age);  //访问非静态属性
      show();   //调用静态方法
      
  }
  static void printUserInfo(){
    
    //静态方法
        print(name);   //静态属性
        show();        //静态方法

        //print(this.age);     //静态方法没法访问非静态的属性
        // this.printInfo();   //静态方法没法访问非静态的方法
        // printInfo();

  }

}

main(){
    
    
  // print(Person.name);
  // Person.show(); 


  // Person p=new Person();
  // p.printInfo(); 


  Person.printUserInfo();
}

2. Object operators in Dart

Object operators in Dart:
? Conditional operator
as Type conversion
is Type judgment
... Cascade operation (concatenation)

class Person {
    
    
  String name;
  num age;
  Person(this.name, this.age);
  void printInfo() {
    
    
    print("${this.name}---${this.age}");
  }
}

main() {
    
    
  // Person p;
  // p?.printInfo();   //已被最新的dart废弃 了解

  //  Person p=new Person('张三', 20);
  //  p?.printInfo();   //已被最新的dart废弃 了解



  // Person p=new Person('张三', 20);
  // if(p is Person){
    
    
  //     p.name="李四";
  // }
  // p.printInfo();
  // print(p is Object);



  // var p1;

  // p1='';

  // p1=new Person('张三1', 20);

  // // p1.printInfo();
  // (p1 as Person).printInfo();




  //  Person p1=new Person('张三1', 20);

  //  p1.printInfo();

  //  p1.name='张三222';
  //  p1.age=40;
  //  p1.printInfo();




  // Person p1 = new Person('张三1', 20);
  // p1.printInfo();
  // p1
  //   ..name = "李四"
  //   ..age = 30
  //   ..printInfo();
}