printing : Java Glossary

In Java, print usually means text display on the video console log such as System.out. Note that System.err and System.out are PrintStreams not PrintWriters. See the File I/O Amanuensis for code samples. However, in general, the term printing usually means creating hardcopy on paper.

There are two kinds of physical printing:

• When you know the brand of printer you have and the control codes it likes and you want to send raw bytes to it. Most often you want to do this when your printer handles PostScript. You send an entire PostScript program that builds the images page by page as the PostScript program executes, much as if it were building a screen image.
  parallel port or USB port
  System.exec
• You don’t know what kind of printer you have. You want to use generic methods and have the operating system convert them into the codes the printer likes. For this technique to work, the printer must be configured in the OS (Operating System) with a device driver and be accessible to your program as the default printer.

Java’s usual idea of printing is essentially building a virtual screen display and taking a snapshot of it. You build it page by page the same way you build a screen. You don’t emit characters in a stream with embedded control chars the way you did in DOS (Disk Operating System) days.

For the rest of this discussion, I will be mostly referring to the second type printing. Within that, there are three different APIs (Application Programming Interfaces) to choose from.

• Since Java 1.1: java.awt.PrintJob and related classes.
• Since Java 1.2: java.awt.print packages.
• In Java 1.3: significant enhancements to both packages.
• Since Java 1.4: The Java Print Service (JPS (Java virtual machine Process Status tool) ) javax.print packages. This is mainly to add support for printing in tiny hand held devices.

Programmers were not happy with the AWT (Advanced Windowing Toolkit) print interface and Sun has made been several attempts to replace the API (Application Programming Interface). This has mainly lead to confusion. The key is to get clear on just which printing API you are using and stick to it.

The Java 1.0 JDK (Java Development Kit) does not support printing.Java version 1.1 does, via java.awt.PrintJob. You print using the same techniques you use for drawing on the screen. It is much like drawing a high-res screen the size of a sheet of paper. Components now have a print method to print themselves which is usually the same as the one to draw them on the screen. To handle text you use Canvases and drawString, or TextFields. To get properly aligned text without borders, consider the KL-Group components or Swing.

In Java version 1.1 unsigned Applets could not print. In more recent versions, they can, though the user has to give an ok.

How To Use PrintJob

For printing on old JVMs (Java Virtual Machines):

In W95, W98, Me and NT, the print job properties are ignored. They are system dependent. But here is how Sun implements them:

How To Use PrinterJob

Java version 1.2 or later PrinterJob is similar to PrintJob. It pops up a platform specific dialog box that the end user fills into select options.

I don’t know how you go about setting attributes that the end user would otherwise have to select in the dialog.

Attributes

Designing Printouts

Faster Printing with javax.print

Dot matrix printing is especially slow. To be quick, you must send text intermixed with printer-specific formatting commands. You can do that with RTextPrinter (not part of standard Java). The following hunk of code presumes you have already, through some other process, created a file file.ps full of PostScript printer commands and you want to get it printed on a printer that can print five double-sided copies on size A4 paper.

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