Moving Toward Object-Oriented Programming - Beginning Java Programming: The Object-Oriented Approach - page 75

secondStudent.id = 2;
secondStudent.firstName = "Sophie";

System.out.println("The student object referred to "+
"by the variable secondStudent has the first "+
"name: "+secondStudent.firstName);
}
}

8.

The behavior of managing students is now cleanly separated from the behavior a student itself
exposes. Later, you might want to create an Administrator class to perform this sort of manage-
ment, but for now, all you want to do is run this simple example program, so the current way of
doing things is fine to illustrate the idea.

Figure 4-2 represents the creation of objects from classes, schematically.

class Student Student myFirstStudent

intid boolean isBirthDay() intid = 1 boolean isBirthDay()

String void giveWarningBoolean String void giveWarning(Boolean

new Student()

String lastName int numberOfFriends() String lastName int numberOfFriends()

int birthYear int birthYear =

int birthMonth int birthMonth

int birthDay int birthDay =

Student mySecondStudent

new Student()

intid = 2 boolean isBirthDay()

void giveWarning(Boolean

String

String lastName int numberOfFriends()

int birthYear =

int birthMonth

int birthDay =

figure 4-2

You have now seen how to create simple class definitions in Java, containing variables and methods.
By now, you should grasp the differences between classes and objects, and should be able to define
classes and to instantiate them. You've been taken on a quick tour through the concepts of classes
and objects in Java, so now that you get the bigger picture, you can take a step back and learn more
about variables and methods, with all their intricacies, which is exactly what you will do in the fol-
lowing sections.