Object-References.java

public class Person {
    // instance variables
    
    String firstName;
    String lastName;
    int age;
    
    // constructor
    
    public Person(String firstName, String lastName, int age) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }
    
    // getters and setters
    ...
        
    public static void main(String args[]) {
        Person person = new Person("Jane", "Trin", 35);
        Person twin = person;
        twin.setFirstName("Steve");
        
        // set Steve's age
        twin.setAge(40);
        
        // set Jane's age
        person.setAge(30);
        
    }    
}