Error: The superclass, ‘Animal’, has no unnamed constructor that takes no arguments.

Problem Description:

Because the constructor cannot inherit
an error is reported during inheritance, which prompts that the constructor in the parent class is composed of parameters. You need to write the constructor in the subclass and pass the constructor of the parent class to parameters

class Animal {
  String name;
  int age;
  Animal(this.name, this.age);

  void printInfo() {
    print('$name is $age years old');
  }
}

//Inherit Animal class by extends keyword
class Cat extends Animal {
 
}

void main(List<String> args) {
  Cat cat = new Cat();
 print( cat.name);
}

Solution:

Super keyword

Try declaring a zero argument constructor in ‘Animal’, or declaring a constructor in Cat that explicitly invokes a constructor in ‘Animal’.dart(no_default_super_constructor)

Try declaring a zero parameter constructor in “animal” or a constructor that explicitly calls the constructor in “animal” in cat.dart (no default super constructor)

class Animal {
  String name;
  int age;
  Animal(this.name, this.age);

  void printInfo() {
    print('$name is $age years old');
  }
}

//Inherit Animal class by extends keyword
class Cat extends Animal {
  Cat(String name, int age) : super(name, age);

}

void main(List<String> args) {
  Cat cat = new Cat("Huahua",3);
 print( cat.name);
}