More-sophisticated behavior - Objects First with Java: A Practical Introduction Using BlueJ - page 194

■ interface The interface of a class describes what a class does and how it can be used with-

out showing the implementation.

■ implementation The complete source code that defines a class is called the implementation

of that class.

■ immutable An object is said to be immutable if its contents or state cannot be changed once

it has been created. Strings are an example of immutable objects.

■ map A map is a collection that stores key/value pairs as entries. Values can be looked up by

providing the key.

■ set A set is a collection that stores each individual element at most once. It does not maintain

any specific order.

■ documentation The documentation of a class should be detailed enough for other program-

mers to use the class without the need to read the implementation.

■ access modifier Access modifiers define the visibility of a field, constructor, or method.

Public elements are accessible from inside the same class and from other classes; private ele-
ments are accessible only from within the same class.

■ information hiding Information hiding is a principle that states that internal details of a class's

implementation should be hidden from other classes. It ensures better modularization of an
application.

■ class variable, static variable Classes can have fields. These are known as class variables

or static variables. Exactly one copy exists of a class variable at all times, independent of the
number of created instances.

Exercise 5.71 There is a rumor circulating on the Internet that George Lucas (the creator of
the Star Wars movies) uses a formula to create the names for the characters in his stories (Jar
Jar Binks, ObiWan Kenobi, etc.). The formula—allegedly—is this:

Your Star Wars first name:
1 Take the first three letters of your last name.
2 Add to that the first two letters of your first name.

Your Star Wars last name:
1 Take the first two letters of your mother's maiden name.
2 Add to this the first three letters of the name of the town or city where you were born.

And now your task: Create a new BlueJ project named star-wars . In it create a class named
NameGenerator . This class should have a method named generateStarWarsName that
generates a Star Wars name, following the method described above. You will need to find out
about a method of the String class that generates a substring.