data class

person_model.java

public class Person {
 
    private String firstName;
    private String lastName;
    private String age;
 
    public Person(String firstName, String lastName, String age){
      this.firstName = firstName;
      this.lastName = lastName;
      this.age = age;
    }
 
    public String getFirstName() {
        return firstName;
    }
 
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
 
    public String getLastName() {
        return lastName;
    }
 
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
 
    public String getAge() {
        return age;
    }
 
    public void setAge(String age) {
        this.age = age;
    }

    @Override public String toString() {
        return "Person(firstName="+ firstName + ", lastName="+ lastName + ", age="+ age + ")";
    }
}

person_model.kt

data class Person(var firstName: String, var lastName: String, var age: String) { 
  
  override fun toString(): String {
        return "Person(firstName=$firstName, lastName=$lastName, age=$age)";
    }
  
}

person_model_call.kt

val person1: Person = Person("John", "Doe", "30")
val person2: Person = Person("Siri", "Doe", "34")

person_model_default.kt

data class Person(var firstName: String? = null, var lastName: String? = null, var age: String = "30")