Moving Toward Object-Oriented Programming - Beginning Java Programming: The Object-Oriented Approach - page 81

I'll explain this by providing an example. Let's modify the Book class so it looks as follows:
class Book {
static int maxAmountOfPages = 500;
String title = "Unknown Title";
String[] authors = new String[]{"Anonymous"};
int yearReleased = 2014, copiesSold = 0, nrOfPages = 1400;
}
Note the static keyword in front of the maxAmountOfPages class variable. This variable denotes
the maximum amount of pages you currently support for topics, which could be used in combi-
nation with the nrOfPages instance variable to check whether you can publish a given book, for
instance. Although the number of pages is different for each book you define, the maximum amount
of pages the printers support is a global property throughout all Book objects, is defined as a class
variable, and is thus accessible by all Book objects.
A code sample illustrating this concept might look like this:
Book superLargeBook = new Book();
superLargeBook.title = "Super Large Boring Book";
System.out.println("I have a book here with the title: "+superLargeBook.title);
System.out.println("Written by: "+superLargeBook.authors);
System.out.println("Released in: "+superLargeBook.yearReleased);
System.out.println("With number of pages: "+superLargeBook.nrOfPages);
System.out.println("However, we only support topics with max. pages: "
+superLargeBook.maxAmountOfPages);
Running this code outputs:
I have a book here with the title: Super Large Boring Book
Written by: [Ljava.lang.String;@1271ba
Released in: 2014
With number of pages: 1400
However, we only support topics with max. pages: 500
Note You might have spotted the following line:
Written by: [ Ljava.lang.String;@1271ba
And wondered what's up with this. This isn't the default Anonymous author you
set! The reason for this behavior is again due to the way Java derives a String
representation of composite types, w hich is not very user friendly in this case.
There are two ways to resolve this issue. The first is to loop through the array
and show each element one by one (you will look at looping constructs in the
next chapter). The second way is to use so‐called “Collection” classes, which
are similar to arrays in the sense that they hold a bunch of information, but are
also much more flexible and efficient. In addition, their String representation
looks much friendlier. You will learn about collections later in this chapter.