GrowingUp.java

public class GrowingUp
{
    public static void main (String args[])
    {

        Infant newBorn = new Infant("Conrad");
        System.out.println("\nHere is what an Infant can do:");
        newBorn.crawl();

        Child aChild = new Child("Bryce");
        System.out.println("\nHere is what a Child can do:");
        aChild.crawl();
        aChild.walk();
        aChild.throwTantrum();

        Adolescent aTeenager = new Adolescent("Alex");
        System.out.println("\nHere is what an Adolescent can do:");
        aTeenager.crawl();
        aTeenager.walk();
        aTeenager.throwTantrum();
        aTeenager.run();
        aTeenager.begForMoney();

        Adult anAdult = new Adult("Samuel");
        System.out.println("\nHere is what an Adult can do:");
        anAdult.crawl();
        anAdult.walk();
        anAdult.throwTantrum();
        anAdult.run();
        anAdult.begForMoney();
        anAdult.goToWork();
        anAdult.payBills();
    }
}

Infant.java

public class Infant {

    private String name;

    public Infant(String n)
    {
        this.name = n;
    }

    public String getName()
    {
        return this.name;
    }

    public void crawl()
    {
        System.out.printf("Hello! My name is %s and I can crawl!\n", this.getName());
    }
}

Child.java

public class Child extends Infant
{
    public Child (String name)
    {
        super(name);
    }

    public void walk()
    {
        System.out.printf("Hello! My name is %s and I can walk!\n", this.getName());
    }

    public void throwTantrum()
    {
        System.out.printf("Hello! My name is %s and I can throw a tantrum!\n", this.getName());
    }
}

Adolescent.java

public class Adolescent extends Child
{
    public Adolescent(String name)
    {
        super(name);
    }

    public void run()
    {
        System.out.printf("Hello! My name is %s and I can run!\n", this.getName());
    }

    public void begForMoney()
    {
        System.out.printf("Hello! My name is %s and I can beg for money!\n", this.getName());
    }
}

Adult.java

public class Adult extends Adolescent
{
    public Adult(String name)
    {
        super(name);
    }

    public void goToWork()
    {
        System.out.printf("Hello! My name is %s and I can go to work.\n", this.getName());
    }

    public void payBills()
    {
        System.out.printf("Hello! My name is %s and can pay bills!\n", this.getName());
    }
}