Person.java

package com.example.app;

public class Person {

    private String firstName;
    private String lastName;
    private int age;

    public String getFirstName(){
        return firstName;
    }

    public String getLastName(){
        return lastName;
    }

    public int getAge(){
        return age;
    }

    public void setFirstName(String firstName){
        this.firstName = firstName;
    }

    public void setLastName(String lastName){
        this.lastName = lastName;
    }

    public void setAge(int age){
        this.age = (age <= 0 || age >100) ? (this.age = 0) : (this.age = age);
    }

    public boolean isTeen(){
        return (age > 12 && age < 20);
    }

    public String getFullName(){
        if (firstName.isEmpty() && lastName.isEmpty()) return "";
        if (firstName.isEmpty()) return lastName;
        if (lastName.isEmpty()) return firstName;
        return (firstName + " " + lastName);
    }


}