Filing and Printing Documents - Beginning Java 2 SDK - page 949

A class that implements the Pageable interface defines an object that represents a set of pages to be printed
rather than a single page. You would implement this interface for more complicated printing situations where
a different page painter may print each page using an individual PageFormat object. It's the job of the
Pageable object to supply information to the PrinterJob object about which page painter and
PageFormat object should be used to print each page. The Pageable interface declares three methods:

getNumberOfPages() Returns the number of pages to be printed as

type int , or the constant value
Pageable.UNKNOWN _ NUMBER _ OF _ PAGES if
the number of pages is not known.

getPageFormat(int pageIndex) Returns the PageFormat object describing

the size and orientation of the page specified
by the argument. An exception of type
IndexOutOfBoundsException will be
thrown if the page does not exist.

getPrintable(int pageIndex) Returns a reference to the Printable object

responsible for printing the page specified by
the argument. An exception of type
IndexOutOfBoundsException will be
thrown if the page does not exist.

A Book object also encapsulates a document that consists of a number of pages, each of which may be
processed individually for printing. The difference between this and an object of a class that implements
Pageable is that you can add individual pages to a Book object programmatically, whereas a class
implementing Pageable encapsulates all the pages. We will look at how both of these options work
later in this chapter.

Creating and Using PrinterJob Objects

Because the PrinterJob class encapsulates and manages the printing process for a given printer that is
external to the JVM, you can't create an object of type PrinterJob directly using a constructor. You
can obtain a reference to a PrinterJob object for the default printer on a system by calling the static
method getPrinterJob() that is defined in the PrinterJob class:

PrinterJob printJob = PrinterJob.getPrinterJob(); // For the default printer

The object printJob provides the interface to the default printer, and controls each print job that you
send to it.

A printer is encapsulated by a PrintService object, and you can obtain a reference of type
PrintService to the object encapsulating the printer that will be used by a PrinterJob object by
calling its getPrintService() method:

PrintService printer = printJob().getPrintService();