flutter how to access the keyword code example

Example 1: 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;
}

Example 2: dart ?? operator

int val1;
final int val2 = 20;

console.log(val1 ?? val2); //result => 20 because val1 is null

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final int val1 = 30;
final int val2 = 20;

console.log(val1 ?? val2); //result => 30 because val1 is not null