Java Reference
In-Depth Information
Creating and Using PrinterJob Objects
Because the
PrinterJob
class encapsulates and manages the printing process for a given physical printer
that is external to the Java Virtual Machine (JVM), you can't create an object of type
PrinterJob
directly
using a constructor. You 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
printJob
object provides the interface to the default printer and controls each print job that you send
to it.
A printer is encapsulated by a
javax.print.PrintService
object, and you can obtain a reference of
type
PrintService
to an object encapsulating the printer that is used by a
PrinterJob
object by calling its
getPrintService()
method:
PrintService printer = printJob().getPrintService();
You can query the object that is returned for information about the capabilities of the printer and the kinds
of documents it can print, but I won't divert down that track for the moment. One point you should keep
in mind is that sometimes a printer may not be available on the machine on which your code is running. In
this case the
getPrintService()
method returns
null
, so it's a good idea to call the method and test the
reference that is returned, even if you don't want to obtain details of the printer.
If multiple print services are available, such as several printers or perhaps a fax capability, you can obtain
an array of
PrintService
references for them by calling the static
lookupPrintServices()
method that
is defined in the
PrinterJob
class. For example:
PrintService[] printers = PrinterJob.lookupPrintServices();
The
printers
array has one element for each print service that is available. If no print services are avail-
able, the array has zero length. If you want to select a specific printer for the
PrinterJob
object to work
with, you just pass the array element corresponding to the print service of your choice to the
setPrintSer-
vice()
method for the
PrinterJob
object. For example:
if(printers.length>0) {
printJob.setPrintService(printers[0]);
}
The
if
statement checks that there are some print services before attempting to set the print service.
Without this you could get an
IndexOutOfBoundsException
exception if the
printers
array has no ele-
ments. Of course, more realistically, you would use methods defined in the
PrintService
interface to query
the printers, and use the results to decide which printer to use.
Displaying a Print Dialog
When you want to provide the user with control over the printing process, you can display a print dialog by
calling the
printDialog()
method for a
PrinterJob
object. This method displays the modal dialog that
applies to your particular print facility. There are two versions of the
printDialog()
method. The version
