Flutter-小知识点

一：单利

class FactoryClass{
 //保存单例
 static final FactoryClass _instance =  FactoryClass._init();
 //私有的构造函数
  FactoryClass._init();
  //工厂构造函数
  factory FactoryClass()=>_instance;
}

二：如何实现类与类比较

可以用重载操作符实现

operatorTest(){
  OperatorClass op1 = OperatorClass(20);
  OperatorClass op2 = OperatorClass(18);
  //正常情况下 是不可以比较对象的，需要重载操作符
  print(op1 > op2);

}
class OperatorClass {
  int age;
  OperatorClass(this.age);
  //重载操作符
  bool operator > (OperatorClass other) => this.age > other.age;
}