Class 16: Java's AWT, Revisited

Held Friday, February 18, 2000

Overview

Today we continue our investigation of Java's Abstract Windowing Toolkit. In particular, we revisit event handling in Java and consider how to lay out windows in the AWT.

Notes

• How to print double-sided from emacs (and also to a particular printer)
  • Options:Printing Options:Command-Line Switches for 'lp' ...
  • Replace the nil with ("-oduplex" "-dpacioli")
  • Of course, you may use whatever printer you want.
• Note also that you should use the pretty-print option in emacs
• Note also that you should use syntax highlighting (fonts, not colors)
• I need to leave town on a family emergency. I'll be gone all next week. Mr. Stone will teach class on MWF. You'll get to watch an interesting video on the design of Java on Tuesday.
  • A transcript of the video is available at http://www.cs.bell-labs.com/who/wadler/steele-oopsla98.pdf
• Due:
  • Exam 1

Contents

• Javadoc
• Events and Listeners, Revisited
• Designing AWT Windows
  • Layout Managers
  • Panels
• Lab G3

Summary

• Javadoc
• Organizing the frame
  • Layout managers
  • Panels
• Event Handling, Revisited
• Lab G3: Java's Abstract Windowing Toolkit, Continued
• Handouts:
  • Preliminary notes on assignment 2
• Due:
  • Exam 1
  • Preparatory reading of Lab G3

Javadoc

• One of the reasons I'm so precise about the structure of your comments is that Java provides a nice utility, javadoc, for producing basic documentation for your code.
• The normal command is

  % javadoc -author Javafiles
  

• This produces HTML files.
• Short lab:
  • Make copies of StudentInfo.java, Address.java, Name.java, and FacultyInfo.java
  • Run javadoc on them as a group.
  • Open the corresponding HTML files in your browser.
  • Make a soft link to the corresponding images with

    % ln -s /home/rebelsky/Web/jdk/docs/api/images .
    

  • Reload

Events and Listeners, Revisited

• There seemed to be some confusion as to how the whole Java AWT event model works, so I'm going to try to draw some pictures to help.

    +----------+     +------------+     +----------+
    |          |     |            |     |          |
    | Object X |-----| Listener A |-----| Object Y |
    |          |     |            |     |          |
    +----------+     +------------+     +----------+
         |
         |
   +------------+
   |            |
   | Listener B |
   |            |
   +------------+
  

Designing AWT Windows

• There are two features of AWT that help you lay out your windows in Java. (We won't necessarily cover them in lab; I'm just trying to give you some extra info.)
• Layout managers give you some basic control.
• Panels let you build subareas.

Layout Managers

• You've already seen FlowLayout. It puts the things in a "row", wrapping to the next row when necessary.
• GridLayout lets you set up an n-by-m grid of components.
  • The components expand to fill the space available.
  • You add the components in order, going across the rows.
• BorderLayout sets up five positions, North, South, East, West, and Center.

Panels

• Panels are what they sound like: areas within a window.
• You add panels just like you add any other component.
• You can have layout managers for panels and add other components to panels.
• We may do a simple example.

Lab G3

Do experiments G3.2 and G3.4 of Lab G3.