doesnt have a default constructor navigation flutter code example

Example 1: flutter constructor default value

class Customer {
  String name;
  int age;
  String location;

  Customer(this.name, [this.age, this.location = "US"]);

  @override
  String toString() {
    return "Customer [name=${this.name},age=${this.age},location=${this.location}]";
  }
}

Example 2: Flutter Constructor

Customer(String name, int age, String location) {
  this.name = name;
  this.age = age;
  this.location = location;
}

Customer(this.name, this.age) {
  this.name = name;
  this.age = age;
}