Dart单例的四种写法

文章目录

• dart中的单例
• 工厂构造 Factory constructor
• 静态变量 Static field with getter
• 静态变量Static field
• 常量和工厂构造 const constructor & factory

dart中的单例

工厂构造 Factory constructor

class Singleton{

  Singleton._privateConstructor();

  static final Singleton _instance = Singleton._privateConstructor();

  factory Singleton(){
    return _instance;
  }

}

void main() {
	Singleton s = Singleton();
}

静态变量 Static field with getter

class Singleton{

  Singleton._privateConstructor();

  static final Singleton _instance = Singleton._privateConstructor();

  static Singleton get instance { return _instance;}

}

void main() {
	Singleton s = Singleton.instance;
}

静态变量Static field

class Singleton {

  Singleton._privateConstructor();

  static final Singleton instance = Singleton._privateConstructor();

}

void main() {
	Singleton s = Singleton.instance;
}

常量和工厂构造 const constructor & factory

class Singleton {
  factory Singleton() =>
    const Singleton._internal_();
  const Singleton._internal_();
}


void main() {
  print(new Singleton() == new Singleton());
  print(identical(new Singleton() , new Singleton()));
}

来源：CSDN

作者：阿拉阿伯

链接：https://blog.csdn.net/rd_w_csdn/article/details/103480996