Java Programming Resources

Table of Contents

• Frequently Asked Questions (FAQ) Lists. Beginner and Advanced.
• Tutorials and Documentation. Online tutorials and books on general and specialized Java topics, the official API, the official language spec.
• Java Booklists.
• Thumbnail Overviews of Java Topics. PostScript Reference Sheets for getting started, object-oriented programming, declaration modifiers, graphics/GUI elements, Threads, network programming, CGI programming, etc.
• Downloading the Java Developer's Kit and Java-Enabled Browsers. Free versions for Windows95, Windows NT, Windows 3.1 (alpha), OS/2, MacOS, and UNIX (Solaris, Linux, Irix, HP/UX, etc).
• Example Applets and Classes. Pen widths for drawing operations, ImageButton, drag-and-drop, network programming, CGI programming, exec, etc. Source code available for unrestricted use.
• CGI Programming. Connecting to CGI programs from Java (GET or POST), using Java to write CGI programs (GET or POST), and the HTML FORM elements.
• Applet and Class Library Collections. General collections, graphics/graphing, and games.
• Resources at Sun. General resources from the Java developers, plus preview of JDK 1.1 and an evaluation copy of Suns development environment Java Workshop.
• Java Security. Security FAQ and various security reports.
• Java Development Environments.
• Free Tools.
• Other Java Resource Pages.
• Papers and Information on Garbage Collection.
• General WWW Resources. HTML Programming, HTML Editors, HTML Validators, Image Collections, CGI resources, etc.

Frequently Asked Questions (FAQ) Lists

• Getting Started
  • Sun's Java FAQ. General questions about obtaining and installing Java, supported platforms, etc. The place to start if you don't yet have Java.
  • Hank Shiffman's "Making Sense of Java" FAQ. Answers very general questions about the Java language.
• Java Programming
  • Digital Focus' "How Do I?" Java FAQ. Detailed answers to Java programming questions.
  • Elliote Rusty Harold's Java FAQ.
  • D'Arcy Smith's FAQ for comp.lang.java.

Tutorials and Documentation

• General/Comprehensive
  • The Java API
    • Index of all fields and methods.
    • All packages.
    • Class Hierarchy.
    • Downloading the API to your local machine.
    • API for the internal "Sun" classes. Generated from the code, and not guaranteed to be supported in any Java version. However, used by all releases of the Sun JDK up through 1.02, and certain requirements (e.g. audio in applications) necessitate them.
  • The Java Language Specification.
  • Sun's Java Tutorial. Online version of The Java Tutorial by Mary Campione and Kathy Walrath, published by Addison-Wesley.
  • Online edition of Special Edition Using Java. From Que Publishing.
  • Online edition of Developing Professional Java Applets. From Sams.net.
  • Brewing Java: A Tutorial. From Elliote Rusty Harold.
  • Digital Espresso. Summarized info from the comp.lang.java Usenet groups.
  • Articles and source code from Java Tutor column of Java Report magazine. From SIGS Publishing.
  • Tutorial de Java (Spanish). Tutorial escrito en espanol por Agustin Froufe.
• Specialized Topics
  • Concurrent Programming in Java. Draft of upcoming text by Doug Lea for Addison Wesley.
  • Tutorial on Threads. This is Chapter 6 of Exploring Java by Pat Niemeyer and Josh Peck (O'Reilly).
  • A tutorial on using Packages. From Mary Smiley et al at NASA.
  • Java Networking FAQ/Tutorial. From James Driscoll.
  • Tutorial and examples on Java optimization. From Jonathan Hardwick.
  • Inter-Applet Communication Tutorial. By Tientien Li.
  • GUI Programming Using Java. Slides on AWT aimed at the Motif Programmer. From Jan Newmarch.
  • What are these "mixins" that advocates of multiple inheritance keep talking about?

Java Booklists

• Comprehensive List of Java/JavaScript Books. By Steve Pietrowicz.
• JavaPages, another Java/JavaScript book list site. By Alan Larkin.
• Moderately comprehensive set of Java book reviews. By Elliote Rusty Harold.

Thumbnail Overviews of Java Topics

• Beginning
  • First look at Java. The simplest application and applet.
  • Putting an applet in a Web page.
  • Reading applet parameters from HTML pages.
• General
  • Classes and object-oriented programming.
  • Declaration Modifiers (public, private, protected, static, final, etc).
• Graphics/GUI Elements
  • Common drawing methods of the Graphics class.
  • Loading/displaying images.
  • GUI Components. Buttons, Lists, Checkboxes, Choice Menus, etc.
  • Scrollbars and Sliders.
  • Composite Components. Panels, Frames, Canvases.
  • Mouse and Keyboard Events.
  • Incremental updating of graphics. Double buffering, using XOR mode, overriding update(), etc.
• Layout Managers
  • Overview: FlowLayout, BorderLayout, null layout, GridLayout, GridBagLayout.
  • Writing custom layout managers.
  • Tips for using layout managers effectively.
• Threads
  • Overview.
  • Some supporting methods.
  • Race conditions and synchronization.
• Network and CGI Programming
  • Network Programming.
  • Introduction to CGI Programming. Two variations of GET, plus POST.
  • Interacting with CGI Programs. Using Java on the client to connect to CGI programs, and using Java on the server to implement CGI programs. Also includes information on wrapping the Java-based CGI programs in shell scripts. Also see the example Java programs (and accompanying shell scripts) in the Examples section.
  • The HTML FORM tag. Buttons, checkboxes, radio buttons, textfields, etc.

Downloading the Java Developer's Kit and Java-Enabled Browsers.

• JDK -- Java Developer's Kit (Free except where noted)
  • Sun/Solaris and X86 Solaris.
  • Windows 95/NT
    • JDK 1.02 from Sun. Original, reference version.
    • SDK from Microsoft. Version from Microsoft that includes Just-In-Time Compiler, ability to create standalone executables, and various MS extensions.
  • Windows 3.1. Early beta version only.
  • MacOS 7.5. See also Apple's MacOS Runtime for Java (MRJ).
  • OS/2 and AIX. See also OSF's release for AIX/PowerPC.
  • SGI. Also see the Cosmo site which includes free JDK and a temporary evaluation copy of a for-fee graphical Java debugger and evaluation tool.
  • HP/UX. See also OSF's release for HP700 series running HPUX 10.x.
  • DEC Alpha. See also OSF's release.
  • Linux.
  • OSF UNIX variants (DASCOM OSF/1, NCR UNIX SysV, Sony NEWS 6.1.1).
  • Partial Ports.
    • Guavac, a Java source-to-bytecode compiler in C++. From David Engberg.
    • Kaffe, a Java VM (bytecode compiler/interpreter). From Tim Wilkinson.
    • Sun-3 (Sun's older 68k-based machines). From James Sanford. Does not support AWT.
• Browsers that Support Java
  • Netscape Navigator (Mozilla). Java support on UNIX, Win 95/NT, MacOS.
  • Microsoft Internet Explorer. Supports Java on Win95/NT. Supports Java on MacOS with the addition of MacOS Runtime for Java (MRJ).
  • IBM WebExplorer. For OS/2.

Example Applets and Classes

• GraphicsUtil. A class that adds pen width arguments to the drawing methods of java.awt.Graphics. Also creates drawCircle and fillCircle methods, adds optional Color arguments to each of the drawing methods, and adds an optional Font argument to drawString and drawChars. Documentation is at http://www.apl.jhu.edu/~hall/java/GraphicsUtil.html, and the code is at .../GraphicsUtil.java and .../GraphicsUtil.class.
• Images as Components
  • ImageLabel. A class that creates a Component containing an image. Like the Label class, it can get positioned by the layout manager and will get repainted automatically. Documentation is at http://www.apl.jhu.edu/~hall/java/ImageLabel/ImageLabel.html, the source code is at .../ImageLabel.java and a small example is at .../ImageLabelTest.html.
  • Icon. A class built on ImageLabel that supports drag and drop for ImageLabels. Ie draggable pictures/icons. Documentation is at http://www.apl.jhu.edu/~hall/java/ImageLabel/Icon.html, the source code is at .../Icon.java and a small example program is at .../IconTest.html. Requires ImageLabel.java.
  • ImageButton. A button class built on ImageLabel. It generates ACTION_EVENTS so that it can be processed just like regular Buttons, can be created simply by passing the String or URL of the image to the ImageButtonConstructor, and shows a darkened image when the button is depressed. Documentation is at http://www.apl.jhu.edu/~hall/java/ImageLabel/ImageButton.html, the source code is at .../ImageButton.java and a small example program is at .../ImageButtonTest.html. Requires ImageLabel.java.
• JavaStub. An application that simplifies prototyping of applets by generating stub files for you. Given a partial filename like HelloWorld, it generates a mostly blank but working class HelloWorld.java which can be run as either an applet or an application. It also generates HelloWorld.html with an APPLET statement that loads HelloWorld.class. Documentation is at http://www.apl.jhu.edu/~hall/java/JavaStub.html, and the code is at .../JavaStub.java and .../JavaStub.class.
• Exec. A class that simplifies executing remote commands from Java applications. Documentation is at http://www.apl.jhu.edu/~hall/java/Exec.html, and the code is at .../Exec.java and .../Exec.class.
• Network Programming Note that there are PostScript reference sheets which provide explanation that these examples illustrate.
  • GetURL, an application that takes a URL as input and retrieves the file. Talks directly to the HTTP server rather than using URLConnection to illustrate sockets.
  • Expn, an application that finds info on an email address. Given hall@apl.jhu.edu connects to the SMTP server on apl.jhu.edu and issues "expn hall". A simple illustration of sockets in Java.
• CGI Programming
  All of these are available in http://www.apl.jhu.edu/~hall/java/CGI/. There are also PostScript reference sheets which give an overview of CGI programming, a survey of interacting with CGI programs (sending to programs that expect GET or POST from Java and writing CGI programs in Java that receive GET or POST requests), and a summary of using the HTML FORM elements.

  Java Source	Shell Script	Description	Online Example
  SearchYahoo.java	N/A	A simple example of an applet as a CGI client. An applet interface to the Yahoo search engine.	SearchYahoo.html
  CGIShow.java	N/A	Generates an HTML page by printing it to standard output (plus a Content-Type line). Used by all of the following programs.	N/A
  CGIGet1.java	CGIGet1	Used to process GET requests that do not contain "=" in the data (ie the HTTP server sends the data as command line arguments).	Attaches '?foo+bar'.
  CGIGet2.java	CGIGet2	Used to process GET requests that contain "=" in the data (ie the HTTP server puts the data in the QUERY_STRING environment variable).	Attaches '?x=foo&y=bar'.
  IsIndex.java	IsIndex	Uses the HTML ISINDEX tag to generate GET requests.	Enter data interactively.
  CGIPost.java	CGIPost	Used to process POST requests. Assumes connecting client sends exactly one line of data (as an HTML FORM would).	Connect from a FORM to see this.

• ShowHTML. A Netscape3-specific way of generating HTML on-the-fly or reading it from a stream and sending it to the browser. Defines showPage(applet, htmlString) and showPage(applet, htmlString, frameName) methods. Source is available at http://www.apl.jhu.edu/~hall/java/CGI/ShowHTML.java, and a test page that illustrates it is at .../TestHTML.html.
• MouseEvents. Reports all mouse events (mouseMove, mouseDrag, mouseDown, etc) to standard output. Differentiates among single and double clicks, left/middle/right mouse. Source is available at http://www.apl.jhu.edu/~hall/java/MouseEvents.java, and a test page that illustrates it is at .../MouseEvents.html. Don't forget to open the Java Console (from Options menu) when using it from Netscape.
• NQueens. Solves the N-Queens problem for N from 4 to 60 in linear time (constant time per queen). The N-Queens problem involves placing N tokens (chess queens) on an NxN grid such that none share a row, column, or diagonal. On an 8x8 grid this amounts to placing 8 queens on a chess board such that none threaten each other. Although this problem is commonly used to illustrate search techniques, there is a common misconception that search is required to find a solution (although search is required to find all solutions). Algorithm adapted from ACM SIGART Bulletin. Run it by loading http://www.apl.jhu.edu/~hall/java/NQueens.html. The source code is at .../NQueens.java.
• ImageWait. A small class that implements getImage but:
  • Waits until the image is loaded before returning, and
  • Allows you to pass a String instead of a URL object, saving the try/catch in the Applet.
  This is just an illustration of using MediaTracker; you should use MediaTracker directly if loading more than one image, since downloading multiple images in parallel is much more efficient than loading one at a time serially. Documentation is at http://www.apl.jhu.edu/~hall/java/ImageWait.html, and the code is at .../ImageWait.java

Applet and Class Library Collections

• General Collections
  • Gamelan, the mega applet collection.
  • Acme Java Software. Applets and class libraries from Jef Poskanzer. Includes a printf-like formatting library.
  • Cup O' Joe. Applets, applications, and class libraries.
  • Java Class Warehouse. Class library collection from James Tauber.
  • The J Files -- Java Centre's applet colllection.
  • SGI's applet collection.
  • JARS -- Java Applet Rating Service. Collection of applets judged "Top X%" (for various X).
  • Applet search engine from applets.com.
  • Yahoo's applet collection.
  • Applets from German Java Repository.
  • Java Boutique -- documented Java applets. From Jason Gurney.
  • Jerry's Java Page. From Jerry Haygood.
  • Applets from "Cool Applets" chapter of Hooked on Java.
• Graphics
  • Cyba Java Pages. Pixelhandler and other graphics libraries.
  • A graphing class in Java. Under the GNU public license, written by Leigh Brookshaw.
  • JavaChart, another free chart/graph package. From Visual Engineering.
  • Jim Buzbee's Hershey Font class.
• Games
  • Brian Cometa's collection of "rated" Java games.
  • Favorite games from Gamelan.
  • Cool Applets and Games. From Mark Boynes.

Resources at Sun

• Sun's main Java homepage.
• Sun's Java FAQ. General questions about obtaining and installing Java, supported platforms, etc. The place to start if you don't yet have Java.
• Obtaining and installing the Java Development Kit (JDK) for Solaris, Win95, Windows NT, and MacOS. Current version is 1.02.
• Sun's top-level documentation page.
• The Java API
  • Index of all fields and methods.
  • All packages.
  • Class Hierarchy.
  • Downloading the API to your local machine.
• The Java Language Specification.
• Sun's Java Tutorial.
• The Java Language Environment: A White Paper.
• Manual pages for javac, java, javadoc, javah, javap, jdb, and appletviewer.
• A preview of JDK 1.1.
• The JDK 1.1 "Inner Classes" specification. This lets you do the equivalent of first class methods, closures and all. However, Sun is wavering on including it in 1.1. If you have an opinion, make it known to Sun by sending to innerclass-comments@lukasiewicz.Eng.Sun.COM.
• JDBC Info and API.
• Known Bugs
  • JDK 1.02.
  • The 1.02 API.
• Java Workshop. Sun's Web development environment written in Java.
• Schedule of Sun's Java training courses.
• Slides from presentations at the 1996 JavaOne conference.
  • Keynote addresses. In HTML format.
  • Session/Tutorial slides. More useful for most people, but are in PDF format, which requires an Adobe Acrobat viewer. Adobe distributes acroread, a free reader for Windows, Mac, Sun, HP, SGI, and AIX.

Java Security

• Sun's Java Security FAQ.
• Security Flaws found by Princeton (Dean, Felten, Wallach).
  • PostScript paper analyzing Java security and summarizing several security flaws (most of which are now fixed).
  • Attack where custom bytecodes could be generated that run native methods, and are missed by the bytecode verifier. Not fixed as of Netscape 2.01 or JDK 1.01.
  • DNS-spoofing bug. Allows applets to connect to arbitrary hosts instead of just the server from which the applet came. Fixed in Netscape 2.01 and JDK 1.01.
  • Bugs in Sun's alpha HotJava browser. Not present in Netscape or JDK.
  • Summary report of Princeton flaws. Future flaws will be listed here.
• Security Flaws found by David Hopwood.
  • David Hopwood's package/Classloader-spoofing bug. Lets applets run arbitrary native code if the cracker can get a file somewhere (anywhere) on the client system in a location the malicious applet knows about. Fixed in Netscape 2.01 and JDK 1.01.
    • Early report.
    • Details on how files could get on local system.
    • Using Netscape's cache to get files on local system.
    • Results of using Netscape's cache. Later experiments found the same problems on MacOS (but not UNIX).
  • Another fake-the-bytecode-verifier attack, this one from David Hopwood. Like the Princeton attack, it requires custom generation of bytecodes rather than coming from standard Java source, would let the applet run arbitrary native code, and is not fixed as of Netscape 2.01 or JDK 1.01.
  • David's list of known and previous bugs, with discussion. This and the PostScript Princeton paper are probably the best two places to start.
• Sprint's evade-the-firewall bug.
• Mark Ladue's "Hostile Applets" collection (mostly denial-of-service attacks).
  • Links to the applets themselves. You may need to quit Netscape if you run any of them.
  • An article that explains many of the applets, with source code.
• Article by Godmar Back on bypassing Netscape's SecurityManager. This allows applets to do unrestricted operations, so is only for totally secure intranets that run totally trusted applets.
• The comp.lang.java.security Usenet newsgroup.

Java Development Environments

• Symantec Cafe (Windows95/NT, MacOS).
• Borland Latte (Windows 95/NT).
• Microsoft Visual J++ (Windows 95/NT).
• Metrowerks' Code Warrior with Java (MacOS).
• Sun's Java Workshop (Windows95/NT, Solaris).
• Natural Intelligence's Roaster (MacOS).
• Asymetrix' SuperCede.
• Teikade and Kalimantan. A free IDE and debugger written in Java.
• Aleda Freeman's Summary of Tools and Development Environments. Links to most products. Includes reviews.
• Books on Java IDEs. From Cye Waldman.

Free Tools

• JGL, the Java Generic Library. Data structures and algorithms for Java: stacks, queues, sorting, searching, sets, etc. Licensed by Microsoft and Borland, but can be downloaded and used for free.
• Viewing the output of the Java Profiler (java -prof ...).
  • ProfileViewer.
  • HyperProf.
• Georgia Tech's "Sub Arctic" UI Toolkit for Java. By Scott Hudson and Ian Smith.
• SpecJava. A free GUI builder that generates Tcl/Tk or Java code.
• TclJava. A free Tcl/Java integration toolkit. Applications only.
• A free Java-to-C compiler. From Yukio Andoh.
• A public domain C++ to Java translator. From Chris Laffra.
• The Mocha Java decompiler. Generates readable source code from class files. From H.P. van Vliet.
• Java Class Viewer. View the fields and methods of a class file. From Robert Raud.

Other Java Resource Pages

• Team Java. Or jump directly to their Java Links.
• UK's Java Centre.
• Java Repository.
• JavaWorld Magazine's online version. Also see Chuck McManis' Java Resource page, which includes all of the source code from his Java in Depth column in JavaWorld.
• The Java Performance Report.
• Javology Magazine.
• Archive of Strong-Java mailing list. Maintained by James Tauber.
• Yahoo's Java section.
• Mid-Atlantic Java User's Group.
• Java en Mexico. En espanol, escrito por Kevin Raulerson.

Papers and Information on Garbage Collection

• A survey of garbage collection techniques by Paul Wilson. To appear in ACM's Computing Surveys. (PostScript)
• Collection of GC-related papers from the University of Texas.
• Garbage Collection FAQ maintained by David Chase of Centerline.
• GC Articles by Hans-J Boehm at Xerox PARC:
  • Discussion on the complexity of mark-sweep vs. copying garbage collectors. He attempts to refute the claims that copying collectors have better paging performance due to compaction, and that the asymptotic time complexity of copying collectors is necessarily better.
  • Example showing that in some cases explicit allocation/deallocation (malloc/free) can be computationally more expensive than garbage collection. Note that he is not claiming that GC is faster in practice, only refuting the claim that it must be slower.
  • A garbage collector for C and C++.
• Henry Baker's collection of papers, many related to GC. Note that netcom is frequently overloaded, so it might take several tries to connect.
• Large garbage-collection bibliography from Richard Jones.
• Great Circle: A commercial collector for C/C++.

General WWW Resources

• High-Level WWW Resources
• Search Services
• HTML Programming
• Web-Related Graphics
• HTML Editors
• HTML Validators
• CGI Programming and Server-side Customizations
• Browsers