Starting University COSC and learning JAVA, advice please :D

**IchBin** · Feb 4 '06, 02:45 AM

Re: Starting University COSC and learning JAVA, advice please :D

David Van D wrote:[color=blue]
> Hi there,
>
> A few weeks until I begin my journey towards a degree in Computer
> Science at Canterbury University in New Zealand,
>
> Anyway the course tutors are going to be teaching us JAVA wth bluej and
> I was wondering if anyone here would be able to give me some tips for
> young players such as myself, for learning the language.
>
> Is this the best Newsgroup for support with JAVA?
>
> I don't know how i'm goina go this year, im mainly worried about MATH115
> which is supposed to be to do with Logic, Algorithm's and alot of
> theory...
>
> I'm sure you'll be hearing from me a fair bit throughout the year as I
> travel on my journeys to complete Geekdom.[/color]

David,
As to your new adventure, absorb all that you can of the abstract nature
of the computer science field. Do not EVER, NOT QUESTION anything you
will bump into, on your path. Have a very open mind and enthusiasm of
curiosity of say Richard Feynman. If you do not know who he is then do
some research. You would be best to listen to his Caltech Physics
lectures or any video of him presenting any topic. At least hear him
converse. He died sometime ago but for myself I pride myself to have a
tenth of the curiosity that he had. So lots of luck to you.

As far as the best newsgroups here is information about the Java NG's
here. After that "comp.lang.java .gui FAQ". Finely "Places you MUST see
as a Beginner".

*comp.lang.java .{help,programm er} - what they're for (mini-FAQ 2004-10-08)*

Before posting read Jon Skeet's "How to get answers on the
comp.lang.java. *
newsgroups" at http://www.pobox.com/~skeet/java/newsgroups.html

Java FAQs and advice:
- Java FAQ (Andrew Thompson) http://www.physci.org/codes/javafaq.jsp
including his list of other FAQs

Page not found | Physci.org

http://www.physci.org/codes/javafaq.jsp#faq

- Java/Javascript/Powerbuilder HOWTO (Real Gagnon)

Real's How-to

http://www.rgagnon.com/howto.html

Real's HowTo : Useful code snippets for Java, JS, PB and more

- Java Glossary (Roedy Green) http://www.mindprod.com/jgloss.html
- jGuru jFAQs (John Zukowski) http://www.jguru.com/jguru/faq/
- Focus on Java (John Zukowski) http://java.about.com/
- Java Q&A (David Reilly) http://www.davidreilly.com/jcb/faq/
- Java GUI FAQ (Thomas Weidenfeller) http://www.physci.org/guifaq.jsp

comp.lang.java. help Set-up problems, catch-all first aid.
According to its charter, this unmoderated group is for immediate help
on any Java problem, especially when the source of the difficulty is
hard to pin down in terms of topics treated on other groups.
This is the appropriate group for end-users, programmers and
administrators who are having difficulty installing a system
capable of
running Java applets or programs. It is also the right group for
people trying to check their understanding of something in the
language, or to troubleshoot something simple.

comp.lang.java. programmer Programming in the Java language.
An unmoderated group for discussion of Java as a programming language.
Specific example topics may include:
o types, classes, interfaces, and other language concepts
o the syntax and grammar of Java
o threaded programming in Java - sychronisation, monitors, etc.
o possible language extensions (as opposed to API extensions).
The original charter said that discussion explicitly should not
include
API features that are not built into the Java language and gave
examples
like networking and the AWT. These days AWT belongs in clj.gui, and
networking (and many other APIs) are often discussed in
clj.programmer.

Do not post binary classfiles or long source listings on any of these
groups. Instead, the post should reference a WWW or FTP site (short source
snippets to demonstrate a particular point or problem are fine). For some
problems you might consider posting a SSCCE (Short, Self Contained,
Correct
(Compilable), Example); see http://www.physci.org/codes/sscce.jsp

Don't post on topics that have their own groups, such as:
comp.lang.java. 3d The Java 3D API
comp.lang.java. advocacy Arguments about X versus Y, for various Java
X and Y
comp.lang.java. beans JavaBeans and similar component frameworks
comp.lang.java. corba Common Object Request Broker Architecture
and Java
comp.lang.java. databases Using databases from Java
comp.lang.java. gui Java graphical user interface design and
construction
comp.lang.java. machine Java virtual machines, like JVM and KVM
comp.lang.java. security Using Java securely
comp.lang.java. softwaretools Tools for developing/maintaining Java
programs
Don't cross-post between these groups and c.l.j.programme r or .help --
it just
wastes the time of people reading the general groups.

Don't post about JavaScript; it's a different language. See
comp.lang.javas cript instead.

* comp.lang.java. gui FAQ *
_______________ _______________ _______________ _______________ ____________

Table of Contents

PART I =============== =============== =============== =============== =====

SECTION 1 - Introduction
Q1.1 What is this, and what does it contain?
Q1.2 What's not in here?
Q1.3 Where do I find a copy of the FAQ?
Q1.4 There are so many Java FAQs.
Which is the right, official one?
Q1.5 Does Sun support or endorse this FAQ?
Q1.6 I noticed broken links in the FAQ.
Don't you verify them before publishing?
Q1.7 Is there an HTML, Word, <whatever format version of the FAQ?
Q1.8 What is AWT?
Q1.9 What is Swing?
Q1.10 What is SWT?

SECTION 2 - The comp.lang.java. gui Newsgroup
Q2.1 What is the newsgroup's charter? What are acceptable topics?
Q2.2 Which topics are not welcome in the newsgroup?
Q2.3 Where can I find an archive of the newsgroup?
Q2.4 What is an SSCCE?
Q2.5 Why don't people like top-posting? What is top-posting?
Q2.6 Is there more about posting to newsgroups and asking questions?
Q2.7 Does Sun support or endorse the newsgroup?

SECTION 3 - The Top 5 Questions
Q3.1 My GUI freezes or doesn't update. What to do?
Q3.2 How do I update the GUI from another thread?
Q3.3 I have arranged all my widgets nicely on a window. Then I
changed the OS / Java version / font / PLAF. Now everything is
broken. What's going on?
Q3.4 My graphics on a Canvas/JPanel/JComponent, etc. gets
corrupted, or I get a null pointer exception when trying
to draw. How can I avoid this?
Q3.5 How to create a transparent or non-rectangular window?

SECTION 4 - Architecture
Q4.1 What is this Model-View-Controller (MVC) stuff?
Q4.2 What is the Swing single-threading issue?
Q4.3 What is the right way to start a Swing GUI?
Q4.4 What is full-screen exclusive mode?
Q4.5 What is active rendering?

PART II =============== =============== =============== =============== ====

SECTION 5 - Window / [J]Frame / [J]Dialog (Top-Level Containers)
Q5.1 How can I ensure a window is always on top of all other windows
using AWT or Swing?
Q5.2 How can I (de)iconify a window?
Q5.3 How can I replace/remove the icon in the title bar (window
decoration) of a [J]Frame?
Q5.4 How to replace the icon in the title bar (window decoration)
of a [J]Dialog?
Q5.5 My modal dialog goes behind the main window. How can I ensure
it is in front instead?
Q5.6 How to bind the escape key to the JDialog cancel operation?
Q5.7 How can I implement my own JFrame/JDialog close handling?
Q5.8 How Do I center a window on the screen? How do I get the
screen size?
Q5.9 How to ensure a minimum or maximum window size?
Q5.10 How to ensure a particular aspect ration of a window?
Q5.11 How can I delegate the window placement to the window system
or manager?
Q5.12 I need to take some toolbar (dock, panel) size into account when
calculating a window position an/or size. How?
Q5.13 My window layout is displayed incorrectly. I have to move
the window, before the layout is right. What's wrong?
Q5.14 How can I display a Splash Screen at the start of my Program?

SECTION 6 - [J]Component (Widgets)
6.1 General Questions
Q6.1.1 How do I position components (widgets) on a window?
Q6.1.2 How to create a transparent widget?
Q6.1.3 How to create a non-rectangular widget?
Q6.1.4 What are Insets?
Q6.1.5 How do I find a component's top-level container (e.g.
the window)?

6.2 JTree
Q6.2.1 I changed the data / structure for my JTree, but the display
doesn't get updated. What's going on?
Q6.2.2 How do I set a custom icon for a node?
Q6.2.3 How do I remove all my nodes from a JTree at once?

6.3 Styled Text / JEditorPane / JTextPane
Q6.3.1 Can I use RTFEditorKit to read RTF documents created by Word?
Q6.3.2 I have problems using the Swing HTML parser to parse all
kinds of HTML. Is this normal?
Q6.3.3 Some of my CSS styles don't work out. Is this normal?
Q6.3.4 Can I use Swing's HTML support to write a web browser?
Q6.3.5 Can I use Swing's HTML support to build an on-line
help system or e-book?
Q6.3.6 If HTML support is really so broken in Java, what is it
good for?

6.4 [J]TextArea
Q6.4.1 I append text to a JTextArea. How to ensure the text
area is always scrolled down to the end of the text?
Q6.4.2 How to use several different fonts (styles, sizes) in
one [J]TextArea?

6.5 [J]Label / [J]Button
Q6.5.1 How can I have multiple Lines in a [J]Label?
Q6.5.2 I want to have a hyperlink in a [J]Label. How can I do this?
Q6.5.3 How do I make a JButton the default button in a JDialog?

SECTION 7 - JScrollPane
Q7.1 I added a component (e.g. a JPanel with an image) to a
scrollpane, but the scrollpane doesn't show it at the right
size / without scrollbars, etc. What's wrong?

PART III =============== =============== =============== =============== ===

SECTION 8 - Graphics & Painting
Q8.1 What is the equivalent of AWT's Canvas in Swing?
Q8.2 When drawing on a JPanel, the background is garbled.
Q8.3 How do I generate some charts / plots in Java?
Q8.4 How to draw some graphs in Java?
Q8.5 I want to write a diagram editor. Where to start?
Q8.6 How do I draw lines between JLabels on a JPanel?
Q8.7 How to debug graph painting?
Q8.8 I need to draw a tree. How?
Q8.9 I need an algorithm for drawing ...
Q8.10 When I subclass JPanel/JComponent, I need to override paint(),
right?
Q8.11 Why does drawImage() fail when I try to display a loaded image?
Why are the width and height of my loaded image both zero?
Q8.12 How do I resize (zoom in/out) my Graphics?
Q8.13 Where do I find the icons which are used by Swing
itself?
Q8.14 Where do I find typical application icons?

SECTION 9 - Fonts
Q9.1 Which Fonts can I use? Can I use font <xyz?
Q9.2 How to turn on text antialiasing in Swing?
Q9.3 Why do some of my characters get displayed as squares?

SECTION 10 - Other Common Questions
Q10.1 My GUI has rendering problems when the JMenu opens over my
top Panel ...
Q10.2 Can I use Swing for Applets?
Q10.3 How do I change a color/font/etc. globally for an
application?
Q10.4 How do I get all the UIDefaults, and what do they mean?
Q10.5 Why is Swing so slow?

SECTION 11 - Non-GUI Questions
Q11.1 How do I do a text/console UI in Java?
Q11.2 How can I do this JavaScript thing on my web site?
Q11.3 I want to make ...

SECTION 12 - Resources
12.1 Sun's Java Web Site
12.2 Other Sun Sites
12.3 Icons
12.4 Miscellaneous Examples, Tips and Tricks
12.5 Style Guides
12.6 SDK Documentation
12.7 More Swing
12.8 Online Magazines
12.9 Java 2D API
12.10 Java 3D API
12.11 General Java
12.12 More?
Q12.12.1 But I need more!

SECTION 13 - Improvement Suggestions

SECTION 14 - Acknowledgments
_______________ _______________ _______________ _______________ ____________

PART I
=============== =============== =============== =============== ============

SECTION 1 - Introduction
~~~~~~~~~~~~~~~ ~~~~~~~~~

Q1.1 What is this, and what does it contain?

This is the FAQ for the comp.lang.java. gui newsgroup. It mostly deals
with Java Standard Edition Swing issues, and contains some AWT
information, too.

In many cases these are also topics many readers would like NOT to see
discussed again soon.

Q1.2 What's not in here?

This is not a general introduction to programming, Java programming, or
GUI programming. Further it is assumed that the reader is familiar with
Java and GUI terminology.

Also, the following topics are either not covered at all or just cursory
touched, since they are not often discussed in c.l.j.g, have own groups,
and/or the FAQ author is not knowledgeable about them:

* J2ME GUI programming

* Java 3D programming (see <news:comp.lang .java.3d)

* Java game programming

* Computer graphics algorithms
(see <news:comp.grap hics.algorithms )

Q1.3 Where do I find a copy of the FAQ?

1) The FAQ is regularly posted to

<news:comp.lang .java.gui

2) At Usenet archives like

<http://gd.tuwien.ac.at/faqs/faqs-hie...lang.java.gui/
<ftp://ftp.cs.uu.nl/pub/NEWS.ANSWERS/...lang/java/gui/
<http://www.uni-giessen.de/faq/archiv....java.gui.faq/

3) Just search an archive like

<http://groups.google.com/groups?grou....lang.java.gui

4) People have placed (sometimes older) versions of the FAQ on web
sites, too, e.g.

<http://mindprod.com/jgloss/guifaq.html
<http://www.physci.org/guifaq.jsp

5) There is even a Japanese translation around:

<http://homepage1.nifty.com/algafield/JavaGUIFaq19j.html

Q1.4 There are so many Java FAQs.
Which is the right, official one?

There is probably not THE FAQ. Everyone can start an FAQ, and many have
done so (and many have stopped after a few weeks).

See it as some benefit. There is a lot of information out there. Note,
however, that there is at least one so-called "Java FAQ" which just
recycles postings from the comp.lang.java. * newsgroups and distributes
them as a newsletter and as a book. You might consider searching an
archive of the groups instead of paying for this material.

For a list of other FAQs and FAQ lists :-) see the "Resources" chapter
of this FAQ and

<http://mindprod.com/jgloss/faqs.html

Q1.5 Does Sun support or endorse this FAQ?

No, it is just a newsgroup FAQ. Sun probably doesn't know about it.

NOTE: The author of this FAQ does not have any inside information or
contacts to Sun's Java or GUI development team and has never been
contacted by Sun. Therefore, the FAQ's author is not in a
position to forward suggestions to Sun or help with expedited
answers from Sun. Please refrain from such requests.

See also: "Q2.7 Does Sun support or endorse the newsgroup?"

Q1.6 I noticed broken links in the FAQ.
Don't you verify them before publishing?

No, I don't. I rely on feedback from readers. Also, links might break
at any time, e.g. just seconds after a link has been verified.

Q1.7 Is there an HTML, Word, <whatever format version of the FAQ?

There is no such official version. Some people went through the effort
to convert the FAQ to HTML. I suggest to use the

<http://txt2html.sourceforge.net

software to create am HTML version for personal usage.

See also: "Q1.3 Where do I find a copy of the FAQ?"

Q1.8 What is AWT?

AWT (The Abstract Window Toolkit) is Sun's first Java GUI toolkit. It
is rather limited and uses the native GUI components of the operating
system.

Unless you have to support an old VM, Swing is usual the better choice
for a Java GUI toolkit.

Q1.9 What is Swing?

Swing is Sun's second attempt at a Java toolkit. It is rich in
functions and widgets, and is considered the standard Java GUI
toolkit. Nowadays it is bundled with the Java 2 Standard Edition.

Most parts of Swing are written in Java, especially most of the GUI
components. Swing uses some parts of AWT in order to gain access to the
native GUI system for event handling and top-level containers. It is
build on AWT's lightweight component framework.

Q1.10 What is SWT?

SWT is an alternative GUI toolkit from IBM. Unlike AWT and Swing, it is
not part of the Java 2 Standard Edition. You have to obtain it
separately for the platforms you want to support (it uses a native
library).

SECTION 2 - The comp.lang.java. gui Newsgroup
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~

Q2.1 What is the newsgroup's charter? What are acceptable topics?

The voting for the group with the group's charter passed on
1997-04-10:

<http://groups.google.com/groups?selm...3170%40isc.org

A longer history of comp.lang.java. * reorganizations can be found in

<ftp://ftp.isc.org/usenet/news.announ...p/comp.lang.ja
va-reorg

Here is an excerpt from the '97 reorg charter (Note, "all groups"
refers to all the Java groups from that voting, including
comp.lang.java. gui):

CHARTER: all groups

The normal practice should be that most articles are posted to one
single, correct group ONLY. Cross-posting is only appropriate when
the problem is hard to categorize or when it legitimately concerns
more than one group. Answers should be posted to a single group only
once the nature of the problem has been ascertained. Many articles of
this sort should go to comp.lang.java. help (only).

It is not appropriate to post binary class files or long (longer than
one or two screenfuls) source listings on any of these groups.
Instead, the post should reference a WWW or FTP site (short source
snippets to demonstrate a particular point or problem are fine).

END CHARTER.

[...]

CHARTER: comp.lang.java. gui

This unmoderated group is for any and all discussion relating to
GUI toolkits or window frameworks in Java. Topics include the AWT,
Netscape's IFC, Microsoft's planned AFC, Visix's Vibe toolkit, among
others. The newsgroup will also be the appropriate place for
discussion of the JDK event model, mouse and keyboard issues,
bugs in windowing code, and graphics programming in Java. If it
concerns something that can be seen on the screen, it belongs in this
group.

END CHARTER.

One will note the list of ancient Java GUI technologies, and the
absence of Swing. It is safe to say, that nowadays most discussions are
about Swing, plus a few about AWT and Java printing.

Q2.2 Which topics are not welcome in the newsgroup?

Of course, this question is never asked, but over the time, it has
turned out that certain types of postings are not welcome, even if Java
related. This includes:

* Issues answered in this FAQ are issues most posters don't want
to see discussed again soon.

* Posting your homework.

* Advocacy. Goto comp.lang.java. advocacy instead.

* Postings urging the readers to help. Especially in
conjunction with whining. No one in the group is paid to help
you. No one owns you anything.

* Public and hidden advertising. You think you are too clever
to be caught? Well, read this thread in our sister group
c.l.j.programme r first, and watch how some business lost all
its reputation:

http://groups.google.com/groups?threadm=58882783.
0307010403.67c5 4a5f%40posting. google.com

* Postings which just contain a statement like "Help! It does
not work!", without any additional information, like the
exact error message, source code, or even a hint what "it" is
supposed to mean.

* Postings demonstrating unwillingness to learn are not
welcome, too. And learning starts by reading the API
documentation before posting.

* Test messages are not welcome. Instead, use alt.test.*, and
learn how newsgroups work.

See also: "Q2.4 What is an SSCCE?"

Q2.3 Where can I find an archive of the newsgroup?

See e.g.

<http://groups.google.com/groups?grou....lang.java.gui

Q2.4 What is an SSCCE?

Short/small, self contained, compilable, example (source code).

It would be best if you provide such short (see the group's charter)
example source code in your first request for help. When asked for one,
please don't complain that your source code is too large, too tricky,
too secret for being cut down to a reasonable size and posted. You have
the problem, and you asked in a public forum, so it is in your interest
to provide the requested information.

For more information about hacking some example code together, go to

<http://www.physci.org/codes/sscce.jsp

Q2.5 Why don't people like top-posting? What is top-posting?

See the following Question & Answer (well, Answer & Question) section:

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on Usenet and in e-mail?

-- Common Usenet signature

Q2.6 Is there more about posting to newsgroups and asking questions?

Yes, see e.g. the following for making the most out of a newsgroup
(ignore the hacker slang):

<http://www.catb.org/~esr/faqs/smart-questions.html
[The author of that web page has requested a notice that he is not
a general help desk for all your problems].

<http://www.yoda.arachsys.com/java/newsgroups.html

Also see the newsgroups:

<news:news.newu sers.questions
<news:news.answ ers

And RFC 1855. E.g. at

<ftp://ftp.rfc-editor.org/in-notes/rfc1855.txt
<http://www.faqs.org/rfcs/rfc1855.html

Q2.7 Does Sun support or endorse the newsgroup?

Frankly, no one really knows, but it doesn't appear so. From time to
time a poster can be spotted apparently working for Sun's Swing
development team. But there is no one in an official capacity from Sun
taking part in the discussions.

It is safe to say that the newsgroup isn't of much interest for Sun,
and that suggestions or informed opinions posted to the group will most
likely not be seen, noted or followed-up by Sun.

You might want to try

<http://developer.java.sun.com/developer/bugParade/
or
<http://jcp.org/

if you want to suggest some changes to Java. Good luck.

See also: "Q1.5 Does Sun support or endorse this FAQ?"

SECTION 3 - The Top 5 Questions
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~

Q3.1 My GUI freezes or doesn't update. What to do?

Most likely you are blocking the event dispatching thread (EDT).
Offload time-consuming tasks from your event listeners to separate
threads.

You can do the necessary implementation by hand, it is rather simple:

public void actionPerformed (ActionEvent e) {
new Thread(new Runnable() {
public void run() {
//
// Do some time consuming task
//
...

//
// Update the GUI from within the task
// synchronous: invokeAndWait()
// asynchronous: invokeLater()
//
SwingUtilities. invokeLater(new Runnable() {
public void run() {
//
// GUI code
//
}
});

}
}).start(); // start the thread
}

Or you can use existing frameworks like the SwingWorker class from
Sun. See the series of articles in

<http://java.sun.com/products/jfc/tsc.../threads1.html

SwingWorker is earmarked for inclusion into Java Standard Edition 1.6.

For some special cases you can give paintImmediatel y() a look. See

<http://java.sun.com/products/jfc/tsc...ing/index.html

for some information about using paintImmediatel y().

See also: "Q3.2 How do I update the GUI from another thread?"

Q3.2 How do I update the GUI from another thread?

If you have to update the GUI from another thread (e.g. once you
offloaded a time consuming task from the EDT to another thread) you
should use the javax.swing.Swi ngUtilities.inv okeLater() or
javax.swing.Swi ngUtilities.inv okeAndWait(). Often you want
invokeLater().

The code is rather simple. E.g. when using an anonymous class:

SwingUtilities. invokeLater(new Runnable() {
public void run() {
// Code to be executed on the EDT
}
}
);
// Current thread will immediately continue here

And

SwingUtilities. invokeAndWait(n ew Runnable() {
public void run() {
// Code to be executed on the EDT
}
}
);
// Current thread will wait until code has been executed on
// the EDT.

Again, see

<http://java.sun.com/products/jfc/tsc.../threads1.html

for more details.

See also: "Q3.1 My GUI freezes or doesn't update. What to do?"

Q3.3 I have arranged all my widgets nicely on a window. Then I
changed the OS / Java version / font / PLAF. Now everything is
broken. What's going on?

This sounds as if you don't use layout managers, but instead hard-coded
component sizes and widgets. If you want to avoid this problem, there
is no way around using layout managers, or implementing your own
geometry management from scratch.

Q3.4 My graphics on a Canvas/JPanel/JComponent, etc. gets
corrupted, or I get a null pointer exception when trying
to draw. How can I avoid this?

Do not use Component.getGr aphics(). Instead, subclass and override the
paint() (AWT), or paintComponent( ) (Swing) method.

Component.getGr aphics() simply can't work. Java's normal drawing mode
is called 'passive rendering'. It is based on a callback mechanism.
The drawing code is supposed to sit passively there until Java asks it to
draw something by calling your paint()/paintComponent( ) method.

At that moment you are supposed to provide the Component with the
drawings you would like to do by using the provide Graphics/Graphics2D
drawing context. You are not supposed to "push" graphics information
into a component using getGraphics() or any other means.

This mechanism is necessary so Java can support graphics systems which
don't remember a window's contents when it is obscured (e.g. overlayed
by another window). When the window becomes visible again, such
graphics systems have to ask the application to reconstruct the window
content. Therefore, paint()/paintComponent( ) is supposed to be the
memory of a component. getGraphics(), however, doesn't have any
recollection of previous drawing operations. So once a drawing done via
getGraphics() is lost, it can't be reconstructed. There is nothing in
there that stores the old drawing data, and there is nothing in
AWT/Swing which informs getGraphics() to do some re-drawing.

In addition, there are situations where Component.getGr aphics() simply
returns null. This is a defined behavior of the method. And finally,
most users of getGraphics() forget to dispose the Graphics object after
usage, thus creating a resource leak.

See

<http://java.sun.com/products/jfc/tsc...ing/index.html

for more information about Java's normal painting model.

For very special cases (games, animations, slide shows, etc.), you might
want to flip to an 'active rendering' mode. Active rendering best works
when you wholly one the screen in full-screen exclusive mode.

See also: "Q4.4 What is full-screen exclusive mode?"

Q3.5 How to create a transparent or non-rectangular window?

You can't in a good, platform independent way.

Although particular Swing components can be 'transparent', the
problem is the top-level window. That window is always rectangular, and
in almost all Java implementations non-transparent.

Depending on your circumstances, platform, etc., one of the following
might (partly) work:

1) Ugly Hack, all platforms, Java 1.3+

One hack is to take a snapshot of the underlying screen region using
java.awt.Robot. createScreenCap ture(rectangle) . And then using that
snapshot as a background image for the window. If the background
changes, the illusion is gone.

<http://www-128.ibm.com/developerwork...rary/j-iframe/

is a JFrame subclass which uses Robot to add transparency.

2) Windows

The nativeskin.jar of the Skin LnF at

<https://skinlf.dev.java.net/

provides a Windows-only region feature for building non-rectangular
windows. It comes with a native Win32 library, so applications
written with this library are not portable to other platforms.

It should in principle be possible to write a similar library for
other GUI systems (e.g. X11 with the very common shape extension).

3) Apple OS X

Apple's Java for OS X observes the alpha-component of the window
background color, like one would expect from any Java
implementation. Therefore, any amount of transparency of a
top-level window can be configured by just constructing an
appropriate Color object and setting it as background color. E.g.
the following sets a completely transparent background:

window.setBackg round(new Color(0, 0, 0, 0));

Non rectangular-looking windows can be constructed by

- Turning the normal window decoration of (if any), and

- Using an image (in a format which supports an alpha component,
e.g. PNG) as the window background.

4) Applet

An alternative for applets which might be good enough in some cases
can be found here:

<http://java.sun.com/docs/books/faq/s...ndExample.html

See also: "Q6.1.2 How to create a transparent widget?"
"Q6.1.3 How to create a non-rectangular widget?"

SECTION 4 - Architecture
~~~~~~~~~~~~~~~ ~~~~~~~~~

Q4.1 What is this Model-View-Controller (MVC) stuff?

MVC is a way to structure an application. It is based on the idea of
separating the presentation of data from the data itself. MVC
originated in the Smalltalk world and has since then become a common
design pattern.

Swing uses a variant of MVC (not THE original MVC as Smalltalk users
will point out).

The following TSC article contains a good description of Swing's
architecture and MVC variant:

<http://www.javadesktop.org/tsc/artic...ure/index.html

Q4.2 What is the Swing single-threading issue?

There is really no issue. With very few exceptions Swing is not thread
safe. But it can be safely used in a multi-threaded environment if the
necessary precautions are taken.

There are three simple things to take care of, not more:

1. Call all Swing API methods from the event dispatching thread
(EDT), unless the API documentation states that a method can
be called from another thread (is thread safe).

NOTE: The API documentation has been known to be wrong in
the past. Check Sun's bug parade when in doubt.

2. If you are not in the EDT, but need to call a Swing API
method, use either invokeAndWait() or invokeLater() to
schedule your code for execution on the EDT.

3. Do not block the EDT. That is, don't run time-consuming
tasks on the EDT. Instead, run these tasks in a separate
thread and use an invoke...() method to update the GUI from
that separate thread.

There is really nothing more to it.

See also: "Q3.1 My GUI freezes or doesn't update. What to do?"
"Q3.2 How do I update the GUI from another thread?"
"Q4.3 What is the right way to start a Swing GUI?"

Q4.3 What is the right way to start a Swing GUI?

Sun almost silently changed the recommended GUI startup procedure. At
the beginning of 2004 the examples in Sun's GUI tutorial were changed,
and some rather short "explanatio n" was given. The explanation can be
summarized as: "There is a threading bug somewhere in Swing. To work
around, already build and start the GUI from the EDT". No more useful
information is provided, e.g. if Sun knows the root cause of the bug
and intends to fix it.

So now the official way to build and start (calling setVisible(true ))
the GUI is to use invokeLater(). The shortest version of a GUI
application's main() method becomes:

public static void main(String[] args) {
invokeLater(new Runnable() {
public void run() {
//
// Build and start the GUI here.
//
}
});
}

See also: "Q4.2 What is the Swing single-threading issue?"

Q4.4 What is full-screen exclusive mode?

As the name implies, a means to use the whole screen exclusively for
your applications, like it is e.g. needed for games, industrial control
applications, or slide shows. It was introduced with java 1.4.

You are much closer to the graphics hardware then in normal mode. This
requires some programming techniques which are different from normal
Swing/AWT programming. Full-screen exclusive mode is often used together
with active rendering. See

<http://java.sun.com/docs/books/tutor...een/index.html

Q4.5 What is active rendering?

Active rendering is an a drawing method where you 'push' your graphics
on the screen instead of the usual callback-based method ('passive
rendering') where you wait until you are asked to draw something.

Active rendering results in a completely different application
architecture, and is only recommended for games, animations, etc. It
works best in full-screen exclusive mode. It is often combined with
page-flip BufferStrategy.

See also: "Q4.4 What is full-screen exclusive mode?"
"Q3.4 My graphics on a Canvas/JPanel/JComponent, etc. gets
corrupted, or I get a null pointer exception when trying
to draw. How can I avoid this?"

PART II
=============== =============== =============== =============== ============

SECTION 5 - Window / [J]Frame / [J]Dialog (Top-Level Containers)
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~~~~

Q5.1 How can I ensure a window is always on top of all other windows
using AWT or Swing?

1) Before Java 1.5 you couldn't at all:

AWT and Swing didn't provide this feature. All you could do was to
use a (modal) [J]Dialog, and make sure the [J]Dialog is provided
with the correct parent/owner in the constructor.

2) Since Java 1.5:

You have Window.setAlway sOnTop(), which is inherited by the other
top-level containers like JFrame. However, the implementation is
incomplete, and not supported on all platforms. There are especially
problems with a number of Unix version / Window manager version
combinations.

Q5.2 How can I (de)iconify a window?

1) Before Java 1.2 you had to revert to native calls.

2) Since Java 1.2 you can use [J]Frame.setState( ).

3) Since Java 1.4 you can use [J]Frame.setExtend edState(), too.
setExtendedStat e() provides more features than setState().

Q5.3 How can I replace/remove the icon in the title bar (window
decoration) of a [J]Frame?

Use setIconImage().

To revert to the platform's default icon use:

frame.setIconIm age(null);

On some platforms this might remove the icon. Alternatively you can try
a transparent Image if you don't want to have an icon.

Q5.4 How to replace the icon in the title bar (window decoration)
of a [J]Dialog?

There is only a partial solution to this problem, and it is not
recommended.

A dialog gets its icon from its parent frame. You can create a dummy
frame which you don't show, set the icon of that dummy frame, and use
it in the constructor of the dialog as the dialog's owner:

JFrame dummy = new JFrame();
Image icon = ...
dummyFrame.setI conImage(icon);
JDialog dialog = new JDialog(dummy);

However, this is dangerous. Certain GUI behavior depends on a correct
[J]Frame (parent window) <- [J]Dialog (child window) relation.
Introducing a dummy parent breaks this relation. Things which can go
wrong include (de)iconising of all windows of an application, and
ensuring a modal dialog is always placed on-top of the main window.

Q5.5 My modal dialog goes behind the main window. How can I ensure
it is in front instead?

Make sure you have properly set up the 'owner' of the dialog in the
dialog's constructor. Don't use null, and don't use a dummy frame (to
set the dialog's icon).

Q5.6 How to bind the escape key to the JDialog cancel operation?

First the bad news. Some JComponent, like JComboBox or JTable use the
escape key by themselves. As a result, the following will not work,
unless you manage to remove the escape key handling from these
components.

To bind the escape key to some operation use code like it follows:

final String ESC_ACTION_KEY = "ESC_ACTION_KEY ";
theDialog.getRo otPane().getAct ionMap().put(
ESC_ACTION_KEY,
new AbstractAction( ) {
public void actionPerformed (ActionEvent e) {
//
// perform the action associated with the escape key
//
// e.g. inform all window listeners, or just call
// dispose()
//
}
});

theDialog.getRo otPane().getInp utMap(
JComponent.WHEN _ANCESTOR_OF_FO CUSED_COMPONENT
).put(
KeyStroke.getKe yStroke(KeyEven t.VK_ESCAPE, 0),
ESC_ACTION_KEY
);

Q5.7 How can I implement my own JFrame/JDialog close handling?

Ironically, by setting the JDialog, JFrame, or JInternalFrame default
close operation to do nothing:

theJDialog.setD efaultCloseOper ation(JDialog.D O_NOTHING_ON_CL OSE);

And then adding an own window listener:

theJDialog.addW indowListener(n ew WindowAdapter() {
public void windowClosing(W indowEvent we) {
//
// Ask for closing confirmation,
// perform any necessary cleanup, etc. here.
// Close window if desired.
//
// we.getWindow(). dispose(); // close window
}
});

Q5.8 How Do I center a window on the screen? How do I get the
screen size?

1) Manually, pre 1.4:

Use java.awt.Toolki t.getDefaultToo lkit().getScree nSize() to get the
screen size, and do the math:

import java.awt.*;
Dimension winSize = win.getSize();
Dimension screenSize =
Toolkit.getDefa ultToolkit().ge tScreenSize();
win.setLocation (
(screenSize.wid th - winSize.width) / 2,
(screenSize.hei ght - winSize.height) / 2
);

2) Since 1.4:

Window.setLocat ionRelativeTo(n ull);

Q5.9 How to ensure a minimum or maximum window size?

You can't in a good way. Swing and AWT ignore the minimumSize and
maximumSize attributes. E.g. if your GUI system allows you to
interactively resize a window to the size of 1 x 1 pixels Swing/AWT will
happily allow this.

A few ugly hacks are possible to correct the size after the the unwanted
resizing happened. They are ugly, because the window snaps back, due to
the fact that the original resizing is not prevent but just corrected
with another resizing.

This correction can e.g. be done with an event listener, listening to
window component resizing events. Or it can be done by overriding the
doLayout() method. In both cases, the actual size can be obtained with
getWidth()/getHeight() and, if the size is not acceptable, corrected
with setSize() (which triggers the second resizing and makes the window
jump).

See also: "Q5.10 How to ensure a particular aspect ration of a window?"

Q5.10 How to ensure a particular aspect ration of a window?

You can't in a good way. You can use similar hacks as the ones for
enforcing a minimum or maximum window size.

See also: "Q5.9 How to ensure a minimum or maximum window size?"

Q5.11 How can I delegate the window placement to the window system
or manager?

First of all, you of course need to use a window manager or system which
is capable of placing the windows by its own. The rest depends on the
Java version:

1) Before Java 1.5:

You have no control over the behavior. If you don't specify an
explicit window position this might be interpreted as the position
(0, 0) and the window might be placed there, or it might be
interpreted as a request to position the window where it best fits.

The same might happen when you explicitly specify (0, 0) as the
position. Some systems interpret this as a request to place the
window where it best fits, others just position the window at (0, 0).

2) Since Java 1.5:

Sun has added a hack for specifying the desired behavior. If the
java.awt.Window .locationByPlat form system property is set to true, a
window manager can place a window with the origin (0, 0) or no
specified origin at will. If the property is false, a window with the
origin (0, 0) is indeed positioned at (0, 0).

The behavior can also be specified on a per window, per
setVisible(true ) basis by using Window.location ByPlatform(true )
immediately before setVisible(true ).

Q5.12 I need to take some toolbar (dock, panel) size into account when
calculating a window position an/or size. How?

The information is not available on all platforms. If you are lucky,
Toolkit.getScre enInsets() delivers information about the screen border
space occupied by the toolbar (dock, panel, or whatever your window
system uses). You can uses this information in your calculations.

Insets i = theWindow.getTo olkit().getScre enInsets(
theWindow.getGr aphicsConfigura tion()
);

Do not assume that the desired size is e.g. always in Insets.bottom.
Many graphics systems allow to move the toolbar to the top or a side of
the screen, too. Or they allow to have multiple toolbars. Always take
all four values into account.

In general, for cross-platform compatibility, it is best to not rely on
this information at all. If it is essential for your application then at
least provide some configuration means to manually specify some screen
border space. This way people on systems where the information is not
available can still use your application as desired by you.

See also: "Q6.1.4 What are Insets?"

Q5.13 My window layout is displayed incorrectly. I have to move
the window, before the layout is right. What's wrong?

It is likely that you have changed the layout after you showed the
window. The layout is not redone in such cases, unless you tell the
container to do so. It is best to first finish the construction of
the window before showing it. If you really can't do this, then

1) for AWT:

Call invalidate() followed by validate() on the window.

2) for Swing:

Call revalidate() on the JComponent (JPanel) of which you changed
the layout.

Alternatively one can call pack() after invalidating the window.
Sometimes it is recommended to follow the validate()/revalidate() call
with a repaint(). This should not be necessary, If you have to do so,
it might be a component's opaque handling and or
paint()/paintComponent( ) method is broken.

See also: "Q8.1 What is the equivalent of AWT's Canvas in Swing?"
"Q8.2 When drawing on a JPanel, the background is garbled."
"Q3.4 My graphics on a Canvas/JPanel/JComponent, etc. gets
corrupted, or I get a null pointer exception when trying
to draw. How can I avoid this?"

Q5.14 How can I display a Splash Screen at the start of my Program?

In general, if you add a splash screen to your application, be nice to
your users and allow it to be turned off via some configuration option.
Splash screens can become very annoying.

1) Up and including Java 1.5

Use an (AWT) Window to display some image. Even if your application
has a Swing based GUI, you should only use AWT classes to build the
splash screen. You will anyhow have to wait until the VM comes up, but
you avoid having to wait for the loading of the huge amount of Swing
classes if you restrict yourself to AWT.

2) Since 1.6

The VM has a command line option for specifying a splash screen
image. That image is displayed even before the VM runs any Java
code. It can be an animated GIF.

java -splash:splashIm age.gif ...

Java 1.6+ also has an API for accessing and manipulating the splash
screen once the Java program is running. See the
java.awt.Splash Screen class.

And Java 1.6+ has a corresponding Manifest file keyword for
specifying a splash screen image:

SplashScreen-Image: splashImage.gif

SECTION 6 - [J]Component (Widgets)
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~~~~

6.1 General Questions

Q6.1.1 How do I position components (widgets) on a window?

You add them to [J]Panels and use one or more of the many layout
managers that come with Java (one for each [J]Panel). And you leave the
exact calculation of the position to the layout managers.

Learning the layout managers is essential to AWT and Swing
programming. Many people don't buy this and think they can get away
without. Later they come to the newsgroup and whine because their GUIs
don't work on other platforms, or don't look good when resized. But
whining will not change their GUIs or the way AWT/Swing works. You have
been warned.

See and work through:

<http://java.sun.com/books/tutorial/u...out/index.html

Q6.1.2 How to create a transparent widget?

First of all it should be noted that being able to have transparent
widgets does not gurantee a transparent window, where the desktop
shines through. In fact, in general the non-transparent top-level
window is where transparency stops.

Since the introduction of the lightweight framework in Java 1.1 it is
possible for a Component subclasses (if lightweight) to have
transparent parts if properly implemented. Lightweight Swing Components
are a special case, since Swing adds a switching mechanism so Swing
components can basically be switched to have a transparent or filled
background.

So there are three different cases:

1) Component (excluding Swing and heavyweight) subclasses

All it takes is a subclass of Component with a paint()
implementation that only draws the non-transparent parts.

If an existing lightweight Component is subclassed to build a
transparent component, it should be made sure that the superclass
doesn't fill the background with the background color in the paint()
method.

2) JComponent (Swing) subclasses

The Swing JComponent subclasses can usually be switched between
painting all pixels within their boundaries or not. This, purely as
a side-effect, effectively allows the programmer to control if the
JComponent's background is non-transparent or transparent.

This behavior is a side-effect of the opaque contract between
JComponents and the Swing repaint manager.

setOpaque(false )

kindly ask a JComponent not to paint all pixels within its
boundaries. For most, but not all, Swing components this results in
a transparent background. If opaque is false, their paintComponent( )
method simply does not fill the background before painting the
component. Also, the repaint manager, it it finds a component with
isOpaque() == false, walks the component hierarchy to find the
component below the current one. Because that one needs to be
repainted first, to provide the background.

Setting setOpaque(false ) doesn't work for all JComponents. E.g. some
contain nested component (e.g. JScrollPane) which need to be changed
to be transparent, too. Or some PLAFs ignore the opaque attribute
and always paint every pixel within their bounds. This behavior is
not illegal, it is still covered by the opaque contract. But it
means that the desired side-effect (transparency) of setting opaque
to false will not work.

3) Heavyweight Components

Transparent heavyweight components are not supported in Sun's
Java implementation.

See also: "Q3.5 How to create a transparent or non-rectangular window?"
"Q6.1.3 How to create a non-rectangular widget?"

Q6.1.3 How to create a non-rectangular widget?

The boundaries of a Component (widget) in Java are always rectangular.
Non-rectangular Components can be faked by implementing Components with
a transparent background.

Java will still treat these components as rectangular objects. E.g. The
standard layout managers always use the rectangular boundaries to
layout Components. If another behavior is required for transparent
Components (e.g. partly overlapping boundaries) custom layout mangers
need to be implemented.

See also: "Q3.5 How to create a transparent or non-rectangular window?"
"Q6.1.2 How to create a transparent widget?"

Q6.1.4 What are Insets?

1) Simple answer:

Insets is a data type, describing additional space around some type
of rectangle space, e.g. a component. A better choice of words would
have been border space.

2) More detailed answer:

There is no consistent usage of the term or the Insets data type in
AWT or Swing. Originally Insets were used in AWT to describe the size
of window decorations, like the size of a Frame's title bar, and
borders in a GridBagLayout. Over the time Insets popped up in all
sorts of places in AWT and Swing. Often there is no exact definition
of what an Insets data type describes, especially in relation to the
size of an item.

For a particular usage of Insets one has to figure out if the Insets
describe additional or subtractive space. Roughly, one has to figure
out, often by experiment, which of the following holds true for a
particular situation:

usable size = item size - insets
total size = item size

or

usable size = item size
total size = item size + inset

The exact relation doesn't matter in the trivial case

Insets = {0, 0, 0, 0}

Q6.1.5 How do I find a component's top-level container (e.g.
the window)?

Use
SwingUtilities. getRoot()

6.2 JTree

Q6.2.1 I changed the data / structure for my JTree, but the display
doesn't get updated. What's going on?

Most likely you are directly manipulating the TreeNodes, instead of
updating the data via the TreeModel. TreeNodes don't have any means to
inform the JTree about changes. This is the job of the TreeModel.

If you use DefaultTreeMode l, all the event notification mechanisms are
already implemented. If you use an own implementation of TreeModel, you
need to implement the necessary event firing yourself.

Don't call repaint() on the JTree. The JTree painting is not broken.
Your event notification is. Get your event notification right.

Q6.2.2 How do I set a custom icon for a node?

If you just want to change the icon for all nodes from the default, get
a DefaultCellRend erer, use the set...Icon() methods, and set the
renderer to be used by the JTree.

If you, however, need different icons for different nodes, then the
following three steps are involved.

1. Create your own TreeNode implementation (or subclass an existing
TreeNode implementation) .

a. Add some means to the TreeNode to identify itself, e.g.

public int getType() { // return a type id }

b. Or let the TreeNode return a corresponding Icon (possibly a
shared instance):

public Icon getLeafIcon() { /* return icon */ }
public Icon getOpenIcon() { /* return icon */ }
public Icon getClosedIcon() { /* return icon */ }

c. Or just rely on the type of your subclass (to be checked with
instanceof). You will have to have an own subclass for each
node which needs a different icon.

2. Subclass DefaultTreeCell Renderer. Override
getTreeCellRend ererComponent() :

2.1. Start with

Component getTreeCellRend ererComponent(
JTree tree, Object value,
boolean sel, boolean expanded, boolean leaf,
int row,
boolean hasFocus)
{

And continue, depending on your TreeNode implementation:

2.2a If you use a getType() method:

YourTreeNode node = (YourTreeNode)v alue;
// Use a lookup table (faster), some factory, or:
switch(node.get Type()) {
case: ...
setLeafIcon(... );
setOpenIcon(... );
setClosedIcon(. ..);
break;
}

2.2b If you use a getIcon() method:

YourTreeNode node = (YourTreeNode)v alue;
setLeafIcon(nod e.getLeafIcon() );
setOpenIcon(nod e.getOpenIcon() );
setClosedIcon(n ode.getClosedIc on());

2.2c If you rely on the type:

if(value instanceof YourTreeNode) {
setLeafIcon(... );
setOpenIcon(... );
setClosedIcon(. ..);
} else if(value instanceof ...) ...

2.3. And finish with:

return super.getTreeCe llRendererCompo nent(
tree, value,
sel, expanded, leaf,
row,
hasFocus);

}

3. Use JTree.setCellRe nderer() to set your renderer.

Q6.2.3 How do I remove all my nodes from a JTree at once?

Just replace the model. Deleting all nodes individually is a waste of
time.

JTree's API documentation does not indicate if it is permissible to use
null as a model, but it is known to work in Sun's reference
implementation:

tree.setModel(n ull);

If you don't trust his code, create an empty model and use it instead
of null.

6.3 Styled Text / JEditorPane / JTextPane

Q6.3.1 Can I use RTFEditorKit to read RTF documents created by Word?

Well, you can try. The RTFEditorKit is, however, very limited. There is
a subtle hint in the RTFEditorKit API documentation. It points out that
the Swing team "hops" to improve the class in the future. This hint is
there since the first release of the class years ago.

The newer your Word is, the less likely it is that the RTFEditorKit can
read the RTF. There have been reports about crashes when using RTF
generated by the latest Word version.

Q6.3.2 I have problems using the Swing HTML parser to parse all
kinds of HTML. Is this normal?

Unfortunately it is. The Swing HTML parser is the old HotJava parser
(Sun's pure Java web browser, once a separate product). It is limited
and hasn't been updated for a long time. In principle it can deal with
HTML 3.2 and style sheets. In practice it is picky.

Use another parser if you have problems, or convert your HTML with HTML
Tidy or its Java port JTidy before trying to read it.

<http://tidy.sourceforge.net/
<http://jtidy.sourceforge.net/

Q6.3.3 Some of my CSS styles don't work out. Is this normal?

Yes, for the same reasons as described in the previous answer. See the
class javax.swing.tex t.html.CSS for a list of the officially supported
CSS attributes, and brace yourself for some more deviations.

Q6.3.4 Can I use Swing's HTML support to write a web browser?

You can, but the resulting browser will suffer from the limitations of
Swing's HTML parser and CSS handling. The parser was in fact originally
developed for Sun's HotJava web browser. But this was years ago, and
HotJava was never a serious competitor in the browser business.

To get some ideas have a look at

<http://java.sun.com/developer/online...g1/shortcourse.
html#JFCEditorP ane

Q6.3.5 Can I use Swing's HTML support to build an on-line
help system or e-book?

Sure you can. Or, you could take Sun's JavaHelp, which does exactly
this. It uses the Swing HTML components to parse and render help text
or other text written in HTML. It also provided for navigation and
other common help features.

Q6.3.6 If HTML support is really so broken in Java, what is it
good for?

As long as you have the generation of the HTML under your control it is
quite usable. E.g. the JavaHelp system uses Swing's HTML parser and
display capabilities.

If you need to handle real-world HTML from sources not under your
control, you better look for some other parser. E.g.

<http://htmlparser.sourceforge.net/

gets recommended often.

6.4 [J]TextArea

Q6.4.1 I append text to a JTextArea. How to ensure the text
area is always scrolled down to the end of the text?

textarea.setCar etPosition(text area.getDocumen t().getLength() );

Q6.4.2 How to use several different fonts (styles, sizes) in
one [J]TextArea?

You can't. Use a J[Editor|Text]Pane.

6.5 [J]Label / [J]Button

Q6.5.1 How can I have multiple Lines in a [J]Label?

1) Label

You can't. Use a TextArea instead, and turn editing of the TextArea
off.

2) JLabel

2.a) Use HTML markup in the label's Text. E.g.:

theJLabel.setTe xt("<htmlLine 1<brLine 2<brLine 3</html");

2.b) Or use a JTextArea.

Q6.5.2 I want to have a hyperlink in a [J]Label. How can I do this?

You probably don't want to have a label, but a button.

Just configure a JButton so it looks like a link. E.g. use HTML to
format the button's text, and remove the button's border:

b = new JButton("<html< ahttp://java.sun.com</a<html");
b.setBorderPain ted(false);

Provide the button with an ActionListener to handle the ActionEvent
when the button is clicked. Implement whatever is desired in the event
handler. E.g. start an external web browser.

b.addActionList ener(new ActionListener( ) {
actionPerformed (ActionEvent e) {
// start web browser
}
});

Q6.5.3 How do I make a JButton the default button in a JDialog?

It is rather counter-intuitive, by telling the root pane of the JDialog
about the button:

theJDialog.getR ootPane().setDe faultButton(the JButton);

Some PLAFs might ignore this setting.

SECTION 7 - JScrollPane
~~~~~~~~~~~~~~~ ~~~~~~~~

See also: "Q6.1.2 How to create a transparent widget?"
"Q6.4.1 I append text to a JTextArea. How to ensure the text
area is always scrolled down to the end of the text?"

Q7.1 I added a component (e.g. a JPanel with an image) to a
scrollpane, but the scrollpane doesn't show it at the right
size / without scrollbars, etc. What's wrong?

Ensure that the component you added does return its desired size via
getPreferredSiz e(). E.g. if you have a JPanel holding an image, ensure
that the JPanel's getPreferredSiz e() returns the size of the image.

PART III
=============== =============== =============== =============== ============

SECTION 8 - Graphics & Painting
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~

See also: "SECTION 3 - The Top 5 Questions"

Q8.1 What is the equivalent of AWT's Canvas in Swing?

It depends on your purpose, and on the level of compliance you want to
have with the Swing opaque handling.

Use
a) JPanel, if you want to have a "complete" component with a
UI delegate which handles opaque settings (if
paintComponent( ) is correctly overridden).

b) JComponent, if you intend to always draw every pixel in the
area of the component (and break the opaque attribute API
contract, don't worry, most likely no one will notice). If
you need to have your own special key and mouse processing,
you might also want to start with JComponent and create
your own UI delegate.

c) You could even start higher up in the inheritance chain.
java.awt.Compon ent is lightweight since Java 1.1. However,
you will not get Swing additions like double-buffering.

d) Canvas. No joke. Under very special circumstances (e.g.
game programming, accelerated graphics) AWT's Canvas might
be the right thing to use, even under Swing. Under normal
circumstances, however, this is not the right choice,
because it brings the problem of mixing heavyweight and
lightweight components.

If this is all Greek to you, use JPanel. And remember, if you use
JComponent or JPanel, override paintComponent( ), not paint().

Q8.2 When drawing on a JPanel, the background is garbled.

It is likely that you managed to break the opaque handling of the
component. Your JPanel instance promises (via getOpaque()) to draw
each and every pixel under its influence, but doesn't.

Start your paintComponent( ) method with a call to
super.paintComp onent(g) (which honors the opaque attribute and fills
the background with the background color). Also, check the setting of
the opaque flag, and have a look at the TSC article about "Painting".
See the list of resources at the end for a link.

Q8.3 How do I generate some charts / plots in Java?

If you want to do the drawing in Java, consider using a chart drawing
library. E.g.

<http://www.jfree.org/jfreechart/index.html
<http://www.jgraph.com/

get recommended often. The web site also has a list of other chart
libraries.

If you just have to plot some (scientific) data, and if you can live
with an external C program, consider using gnuplot

<http://www.gnuplot.info/

Millions of scientific papers around the world have been illustrated
with gnuplot output.

Use Runtime.exec() to pipe the plot commands and data into gnuplot, or
just write the data to a file and use gnuplot separately.

Q8.4 How to draw some graphs in Java?

Non-trivial graph drawing is a serious business. If you want to do it
all by yourself, reserve some time and start studying graph drawing
algorithms. See the question "I need an algorithm for drawing ..." for
information where to start searching for such algorithms. Then, or in
parallel, start studying the Java 2D API.

If you don't want to concern yourself with the algorithm
implementation, use a graph library like:

<http://jgrapht.sourceforge.net/
<http://jung.sourceforge.net/

Or check if the algorithm used in Sun's GraphLayout applet demo is
suitable for your purpose. The source comes with every SDK, see the
directory

demo/applets/GraphLayout

in you SDK installation.

If you can live with an external C tool, give The Dot a try. It is part
of graphviz at

<http://www.research.att.com/sw/tools/graphviz/refs.html

Or, if you don't require a Java solution and if you are on a Unix with
a complete troff installation, including pic, you can use pic for
typesetting simple graphs.

See also: "Q8.9 I need an algorithm for drawing ..."

Q8.5 I want to write a diagram editor. Where to start?

Consider using a framework like

<http://www.jhotdraw.org/
<http://www.jgraph.com/jgraphpad.html
<http://gef.tigris.org/

for a start. You also might want to familiarize yourself with many of
the design patterns in

Gamma, E.; Helm, R.; Johnson, R.; Vlissides, J.: Design
Patterns: Elements of reusable object-oriented Software.
Addison-Wesley professional computing series. Brian W.
Kernighan, Consulting Editor. Reading, MA: Addison-Wesley,
1994.

And (if you manage to find the old publications), the early work on
UniDraw and IDraw by Vlissides is also interesting (in C++).

Q8.6 How do I draw lines between JLabels on a JPanel?

You are apparently trying to draw a graph by using normal widgets to
draw the nodes of your graph. This is not a good idea. Consider using
the Java 2D API (nowadays part of J2SE) to draw the complete graph.
Have a look at java.awt.geom for predefined shapes. Also check out
Sun's 2D Programmer's Guide.

Q8.7 How to debug graph painting?

The best way is probably to use a debugger and step through the
paint[Component]() method. There is also the rather obscure
JComponent.setD ebugGraphicsOpt ions() method in Swing. It can be used
to turn several kinds of debugging output on or off.

Please note that setDebugGraphic sOptions(0) does not turn debugging off.
Instead setDebugGraphic sOptions(DebugG raphics.NONE_OP TION) is needed.

See also: "SECTION 12 - Resources"

Q8.8 I need to draw a tree. How?

This seems to be a common homework question, so please have a look at
the "Which topics are not welcome in the newsgroup?" to understand why
this answer is intentionally vague.

If the fixed layout of JTree suits your needs, you could start reading
the JTree API documentation.

Or you could use a simple (recursive) algorithm. E.g

x(node) = K * level(node), and
y(node) = M * inorder_rank(no de).

gives very ugly trees, but trees. If this doesn't get you started, ask
your professor or tutor for more hints. Consult your text book about
(inorder) tree traversal, and consult

<http://home.earthlink.net/~patricia_.../beginner.html

Q8.9 I need an algorithm for drawing ...

First of all, it really helps to know a little bit about math and
geometry. It also helps to know a little bit about coordinate
transformations . Then start with the FAQ for

<news:comp.grap hics.algorithms

which is at

<http://www.magic-software.com/CgaFaq.pdf

Q8.10 When I subclass JPanel/JComponent, I need to override paint(),
right?

Wrong. You are supposed to override paintComponent( ), not paint(). You
would override paint() only when subclassing Canvas.

Swing has a slightly different painting model than AWT. Have a look at
the painting article in TSC. This is highly recommended reading if you
plan to do any kind of drawing or develop a custom component.

See also: "SECTION 12 - Resources"

Q8.11 Why does drawImage() fail when I try to display a loaded image?
Why are the width and height of my loaded image both zero?

The image has most likely not finished loading. Use a
java.awt.MediaT racker to monitor the loading of the image (see the
MediaTracker API documentation for details and an example).

Alternatively, use javax.swing.Ima geIcon to load the image. It already
contains the necessary MediaTracker handling.

Q8.12 How do I resize (zoom in/out) my Graphics?

First of all, it is best to not touch your original data if the
resizing is only for display purposes.

So, if you just want to resize the graphics for display purposes you
have to work on three areas:

1. Use an AffineTransform to construct an appropriate transformation
(see its scale() method). You can also use the Graphics2D.scal e()
convenience method instead. In both cases, however, you should
ensure that you reset the Graphics2D object in your paintComponent( )
method to its original transformation before leaving the method.

2. When you do zooming, it might be handy to not only scale the
graphics, but to also resize the JPanel on which you are drawing, so
the JScrollPane in which you have placed the JPanel updates its
scrollbars accordingly. Be aware, however, that the JPanel size is
in device coordinate space, while your geometry data is hopefully in
user coordinate spaces.

double zf = 1.0;

public void setZoom(double zf) {
// better do some sanity check on the
// zoom factor, too

this.zf = zf;
theJPanel.setPr eferredSize(bas eWidth * zf, baseHeight *zf);
theJPanel.repai nt();
}

public void paintComponent( Graphics g) {
super.paintComp onent(g);

//
// Save the old AffineTransform state of the
// graphics object. Either by remembering the
// AffineTransform , or by just working on a
// copy of the Graphics object.
//
// Variant (a): Save the old AffineTransform
Graphics2D g2d = (Graphics2D)g;
AffineTransform orig = g2d.getTransfor m();
//
// Variant (b): use a copy of the Graphics context
// Graphics2D g2d = (Graphics2D) ((Graphics2D)g) .create();

//
// Now scale the Graphics context
//
g2d.scale(zf, zf);

// ~~~ Draw graphics here ~~~

//
// Reset Graphics state before leaving
// Variant (a): If old AffineTransform has been saved:
// Reset transformation
g2d.setTransfor m(orig);
//
// Variant (b): If a copy of the graphics was used:
// Just destroy copy
// g2d.dispose();
}

3. If you provide some means to select parts of the graphics or
interact in some other way with the graphics using the mouse, you
have to scale (divide by the zoom factor) the mouse event
coordinates, too. You could also use an AffineTransform with the
inverse scaling for this, but for the simple linear scaling used for
zooming, dividing the coordinates will do.

The easiest is probably to do this calculation in the event handler
which is supposed to provide the interaction with the graphics.
Sometimes it is suggested to use the glass pane to intercept all
mouse events of the JPanel and transform them before forwarding.

Q8.13 Where do I find the icons which are used by Swing
itself?

Most of them are hard-coded, and a lot of them don't have any
documented public API and are hidden in the PLAF's implementation. Some
can be found in javax.swing.pla f.basic.BasicIc onFactory, the ones for
Metal can be found in javax.swing.pla f.metal.MetalIc onFactory.

In general, most PLAFs list their icons in the UIDefaults.

See also: "Q10.4 How do I get all the UIDefaults, and what do they mean?"

Q8.14 Where do I find typical application icons?

See also: "12.3 Icons"

SECTION 9 - Fonts
~~~~~~~~~~~~~~~ ~~

See also: "Q6.4.2 How to use several different fonts (styles, sizes) in
one [J]TextArea?"
"Q3.3 I have arranged all my widgets nicely on a window. Then I
changed the OS / Java version / font / PLAF. Now
everything is
broken. What's going on?"
"Q10.3 How do I change a color/font/etc. globally for an
application?"
"Q10.4 How do I get all the UIDefaults, and what do they mean?"

Q9.1 Which Fonts can I use? Can I use font <xyz?

See the API documentation of the Font class for a start:

<http://java.sun.com/j2se/1.5.0/docs/.../awt/Font.html

Q9.2 How to turn on text antialiasing in Swing?

First of all, people have reported mixed results with using
antialiasing in Swing. The improvement is sometimes not as expected,
depending on the font, font size (it works better with larger fonts),
font renderer in use, and e.g. monitor resolution. So it is best to
test the results on the target platform, and make it a configurable
option.

1) Before Java 1.5:

Turning text antialiasing on for one particular component is
relatively simple, turning it on for all components of a GUI is a
nightmare.

To turn antialiasing on for a component you have to subclass and
override paintComponent( ):

public void paintComponent( Graphics g) {
Graphics2D g2 = (Graphics2D) g;

g2.setRendering Hint(
RenderingHints. KEY_TEXT_ANTIAL IASING,
RenderingHints. VALUE_TEXT_ANTI ALIAS_ON
);

g2.setRendering Hint(
RenderingHints. KEY_RENDERING,
RenderingHints. VALUE_RENDER_QU ALITY
);

super.paintComp onent(g2);
}
}

To turn antialiasing on for a whole GUI you would have to subclass
all used components the way described above, and then only use this
components. Or use a PLAF which does this for you. Such PLAFs are
e.g.

<http://smoothmetal.sourceforge.net/
<http://wraplf.l2fprod.com/

2) Since Java 1.5

It is now possible to globally turn on text antialiasing by setting
the system property "swing.aate xt" to "true" on the command line.

The pre Java 1.5 methods still work, too.

Q9.3 Why do some of my characters get displayed as squares?

1) If this happens in a GUI

Java didn't find matching a visual representation (glyph) in the
font you used. In such a case Java uses a square to denote that it
doesn't know how to draw the character.

The fix depends on what you intended to do:

1a) If you indeed intended to display the character in the GUI, then
you need to find and use a font which contains the glyph for the
character.

<http://java.sun.com/j2se/1.5.0/docs/...intl/font.html

has some information which glyphs can be found in Java 1.5's
bundled physical fonts.

The documents at

<http://java.sun.com/j2se/1.4.2/docs/.../fontprop.html
<http://java.sun.com/j2se/1.5.0/docs/...ontconfig.html

describes how Java's font lookup happens, and how this can be
changed on VM level. However, using java.awt.create Font() is much
more preferable than requiring an end-user to change the VM
configuration.

1b) If you didn't intend to display the character, then you probably
felt victim to the fact that many Java widgets don't interpret
control characters like new-lines in Strings.

For example JLabel or JButton do not do this. Instead, they just
try to render the character with a glyph. But usually a font
doesn't contain glyphs for control character code points. So you
get squares instead.

If you need to get control characters interpreted, then in AWT you
would need to implement an own widget (based on a Canvas), which
lays-out the text as desired. In Swing you can use HTML formating
for most widgets:

// Does not work:
JLabel jl = new JLabel("Line1\n Line2");

// Use this instead:
JLabel jl = new JLabel("<htmlLi ne1<brLine2</html");

If you don't want the characters at all, you have to remove them
from the String.

2) You tried to print to the text console

This is not a GUI related issue. Most likely the console works with
a character set which doesn't contain that character at all.

SECTION 10 - Other Common Questions
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~~~~~

Q10.1 My GUI has rendering problems when the JMenu opens over my
top Panel ...

Swing (JMenu) and AWT (Panel) components do not mix well.

See

<http://java.sun.com/products/jfc/tsc...ing/index.html

for things you have to pay attention to.

Q10.2 Can I use Swing for Applets?

You can, if you know that the users of your applets have a Java version
installed which supports Swing. Swing was first shipped with Java 1.2
(it was available earlier as a separate download). Java 1.2 is an old
Java version. You will most probably not develop a Swing application
with it. As a consequence, it is likely that your users need browsers
which support even later Java versions and match your development
version.

Sun provides the Java plug-in in the JRE to update the legacy Java
versions of some browsers to a current Java version. Your applet users
might have to download and install the JRE with the plug-in
separately:

Programmers:

<http://java.sun.com/products/plugin/index.jsp

Consumers:

<http://www.java.com/

Alternatively, you should consider to provide your Swing program as an
application, not an applet, and use Java Web Start to deploy it:

<http://java.sun.com/products/javawebstart/

JavaWebStart is nowadays also a part of the JRE.

Q10.3 How do I change a color/font/etc. globally for an
application?

1) In case you are using Metal, the best way is to implement an own
javax.swing.pla f.metal.MetalTh eme, and set it via
javax.swing.pla f.metal.MetalLo okAndFeel.setCu rrentTheme().

2) For other PLAFs, there is no common API. You can either try to
figure out some undocumented feature, or use the also undocumented
UIDefaults, from which most of the common PLAFs take definitions for
colors, fonts, etc.

See also: "Q10.4 How do I get all the UIDefaults, and what do they mean?"

Q10.4 How do I get all the UIDefaults, and what do they mean?

The UIDefaults contain all kinds of undocumented default settings for
the current PLAF, like colors, icons, fonts, etc. One can guess the
meaning of most of them from the key name, but the keys change for
different PLAFs and VM implementations .

UIManager.getDe faults() returns the UIDefaults. The returned data type
implements, among other things, the Map interface. One can iterate over
this map and display all key/value pairs. There are several small
programs out there doing exactly this, e.g. a popular one is
ShowUIDefaults. java

Q10.5 Why is Swing so slow?

Swing is slow in the hands of unexperienced GUI programmers. In fact,
it has become a common excuse among these to blaim Swing for their own
shortcommings. Shortcommings which for example include a lack of
understanding of the Swing event model or of the repainting mechanism.
Abusing a layout manager is also very popular.

See also: "Q3.1 My GUI freezes or doesn't update. What to do?"
"Q3.2 How do I update the GUI from another thread?"
"Q3.4 My graphics on a Canvas/JPanel/JComponent, etc. gets
corrupted, or I get a null pointer exception when trying
to draw. How can I avoid this?"
"Q4.2 What is the Swing single-threading issue?"

SECTION 11 - Non-GUI Questions
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~

Q11.1 How do I do a text/console UI in Java?

Java is not well-suited for non-graphical user interfaces. You need
platform specific libraries for any sophisticated text UI.

The most common ones are based on the Unix curses/ncurses library, like
JCurses:

<http://sourceforge.net/projects/javacurses/

Note: there happen to be several different libraries out there by the
name JCurses or jcurses which are not entirely compatible.

Another possibility is charva, a text-base UI toolkit on Linux mimicking
the Swing API:

<http://www.pitman.co.za/projects/charva/index.html

Q11.2 How can I do this JavaScript thing on my web site?

Java is not JavaScript. Try

<news:comp.lang .javascript

or another suitable JavaScript newsgroup.

Q11.3 I want to make ...

Programmers usually don't "make" things, they program things :-)
(precise language is important in programming). The first step to
program something is to learn a programming language like Java. Then
you need some knowledge about algorithms and data structures. For Java
you also throw in some object-oriented concepts and principles. But
that's not all. There are many more things to learn, and you can't rush
things. See

<http://www.norvig.com/21-days.html

Since this is the comp.lang.java. gui FAQ, you should also know that it
takes specific skills to develop good or excellent graphical user
interfaces. GUI programming is not just about stirring some widgets
together. It is about good taste, a devotion to details, some knowledge
about color choices, font styles, human-computer-interaction (HCI),
style guides, etc. pp. Especially, Java GUI programming is not HTML
"programmin g".

In short, if you are in a rush to "make" something, consider something
simpler than Java and its GUI toolkits.

SECTION 12 - Resources
~~~~~~~~~~~~~~~ ~~~~~~~

There are many good on-line resources regarding Java GUI programming
out there. The following list is limited by intention to resources
which get recommended often on c.l.j.g, including resources from
regulars.

12.1 Sun's Java Web Site

* Sun's Swing learning by example tutorial (previously the Example
Tutorial, and before that the Quick-Start Tutorial):

<http://java.sun.com/docs/books/tutor...arn/index.html

* Sun's complete Swing Tutorial:

<http://java.sun.com/docs/books/tutor...ing/index.html

* The courses at

<http://java.sun.com/developer/onlineTraining/GUI/

* Sun's Swing Connection (TSC) (Swing developer's site):

<http://java.sun.com/products/jfc/tsc/index.html

With the TSC article index (Swing architecture, Swing and threads,
painting architecture, etc.):

<http://java.sun.com/products/jfc/tsc/articles/

Note: Sun is doing some restructuring of the TSC site. Stuff is moved
back and forth between http://java.sun.com/products/jfc/tsc/ and
http://www.javadesktop.org/tsc/. If something is missing on one site
you might want to check the other.

12.2 Other Sun Sites

There are some GUI articles (some of them dated) at:

<http://java.sun.com/developer/technicalArticles/GUI/

12.3 Icons

It is suggested to check the licenses of each icon collection before
using them in any products.

Sun's well hidden set of Icons for Swing's Metal LnF:

<http://java.sun.com/developer/techDocs/hi/repository/

More icons:

<http://sourceforge.net/projects/icon-collection/
(the link to javalobby.org on that page is broken)

The Ximian Open-Office icons (very nice):
<http://developer.ximian.com/themes/icons/ooo-icons.html

Gnome icons:
<http://tigert.gimp.org/gnome/gnome-stock/

SVG BlueSphere Icon Theme:
<http://svgicons.sourceforge.net/

KDE Icons:
<http://www.buzzard.org.uk/jonathan/kde-icons.html
<http://www.kde-look.org/

12.4 Miscellaneous Examples, Tips and Tricks

A collection of examples for doing nice things with Swing components
(some are a little bit outdated):

<http://www.physci.org/codes/tame/

Originally from

<http://www2.gol.com/users/tame/swing...gExamples.html

which is now off-line.

Christian Kaufhold's Java and Swing info (including JTable info):

<http://www.chka.de/

Jeanette's notes (including JTable remarks):

<http://www.mycgiserver.com/~Kleopatr...wingentry.html

Marco Schmidt's Java resource page (Java imaging information)

<http://schmidt.devlib.org/java/

Karsten Lentsch's company web page:

<http://www.jgoodies.com/

12.5 Style Guides

Java Look and Feel Design Guidelines:

<http://java.sun.com/products/jlf/ed2/book/index.html

Java Look and Feel Design Guidelines: Advanced Topics:

<http://java.sun.com/products/jlf/at/book/index.html

12.6 SDK Documentation

GUI Information in the SDK documentation is commonly overlooked, but
worth some reading:

See your local SDK installation, or

Abstract Window Toolkit (AWT)

<http://java.sun.com/j2se/1.5.0/docs/...awt/index.html

Swing

<http://java.sun.com/j2se/1.5.0/docs/...ing/index.html

2D Graphics and Imaging

<http://java.sun.com/j2se/1.5.0/docs/guide/2d/index.html

Image I/O

<http://java.sun.com/j2se/1.5.0/docs/...eio/index.html

Print Service

<http://java.sun.com/j2se/1.5.0/docs/...jps/index.html

Input Method Framework

<http://java.sun.com/j2se/1.5.0/docs/...imf/index.html

Accessibility

<http://java.sun.com/j2se/1.5.0/docs/...ess/index.html

Drag-and-Drop data

<http://java.sun.com/j2se/1.5.0/docs/...rop/index.html

Swing Examples in the SDK:

See the directory demo/jfc in your Java SDK installation.

12.7 More Swing

Swing class-hierarchy chart

<http://www.holub.com/goodies/java.swing.html

jGuru Swing FAQ

<http://www.jguru.com/faq/Swing

CodeGuru Swing Examples

<http://www.codeguru.com/java/Swing/index.shtml

12.8 Online Magazines

JavaWorld has regular GUI articles. The magazine closed shop on
2004-01-02, but was re-launched March 2004.

<http://www.javaworld.com/

12.9 Java 2D API

The Programmer's Guide

<http://java.sun.com/j2se/1.5.0/docs/...d-bookTOC.html

See also the other SDK documentation.

The 2D Tutorial (a light introduction, avoids the tough stuff):

<http://java.sun.com/docs/books/tutorial/2d/index.html

Sample code

See the demo/jfc directory of your SDK installation. Same as:

<http://java.sun.com/products/java-me...ite/index.html

12.10 Java 3D API

There is a separate newsgroup. see

<news:comp.lang .java.3d
<http://groups.google.com/groups?group=comp.lang.java.3d

12.11 General Java

The Java Tutorial:

<http://java.sun.com/docs/books/tutorial/

All kinds of tutorials:

<http://developer.java.sun.com/developer/onlineTraining/

Roedy's Java Glossary:

<http://www.mindprod.com/jgloss/jgloss.html

12.12 More?

Q12.12.1 But I need more!

Look at the source code. Every SDK comes with the source code of the
public parts of the API. The source code is packed in a file called
src.zip or src.jar (older SDKs), usually right in the top level
directory of your SDK installation.

Also, learn how to use a search engine like

<http://www.google.com

SECTION 13 - Improvement Suggestions
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~ ~~~~~~

Please mail suggestions, corrections, updates, etc. to the author
"cljg_faq" at the host "gmx.de". Your "Subject:" line must contain the
string

[cljg]

somewhere in the line, including the square brackets. Otherwise your
mail will be discarded automatically. In addition, the address is
heavily spam-protected. So if you mail from a spam-invested network,
there is little chance to reach the author. Your alternative is to post
to c.l.j.g.

If you suggest a new entry, please also provide the answer, not only
the question.

SECTION 14 - Acknowledgments
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~

This FAQ contains contributions and help from:

Andrew Thompson, David Postill, Manish Hatwalne, Hiwa, Jeanette.

*Places you MUST see as a Beginner*

If you are learning Java and have a reliable internet connection,
having a look at these places is a must :

For everything Java:

Oracle Java Technologies | Oracle

http://java.sun.com

http://java.net

Excellent IDEs:

Netbeans - www.netbeans.org
Eclipse - www.eclipse.org
IntelliJ IDEA - www.intellij.net
JCreator Pro - www.jcreator.com

For libraries (jars) :

Jars

http://jars.com

Jars on WN Network delivers the latest Videos and Editable pages for News & Events, including Entertainment, Music, Sports, Science and more, Sign up and share your playlists.

For articles, links, blogs, reviews:

TheServerSide | Your Java Community discussing server side development

http://theserverside.com

Java developers discussing Java J2EE, java software, Java programming and other trends in server side development

For source code:

http://javaboutique.internet.com/javasource/

http://www.planet-source-code.com/

Free Java Class Libraries, Source Code, Applets, Beans and Frameworks (thefreecountry.com)

http://www.thefreecountry.com/sourcecode/java.shtml

Free Java Class Libraries, Source Code, Applets, Beans

If you want to read and write XML files in fewer lines of code:

Making Your own Website - HTML, Javascript, PHP, Online marketing and other website making information...

http://dom4j.org

This website will help you set up your own website, and we'll do it absolutely free. Thanks to our site, you'll have your own web page up and running in no time!

If you want to build a lot of java files together and do not prefer and
IDE- Ant:

Apache Ant - Welcome

http://ant.apache.org

(If you haven't used Ant, your life as a Java programmer is poor and
without much value!)

If you want the biggest and the best for free:

Welcome to The Apache Software Foundation | Apache Software Foundation

http://apache.org

If you want servlets and JSP - Tomcat:

Apache Tomcat® - Welcome!

http://jakarta.apache.org/tomcat/

Java docs of everything:

HOME | jdoc.com

http://www.jdocs.com/

⚠️ 본 포스팅은 정보 공유를 목적으로 하며, 배팅을 권유하거나 조장하지 않습니다. 모든 투자의 책임은 본인에게 있으며, 반드시 여유 자금 내에서

Everything of Javadoc:

Oracle Java Technologies | Oracle

http://java.sun.com/j2se/javadoc/writingdoccomments

404

http://filia.uni.lodz.pl/mocny/doc/j2sdk/docs/tooldocs/solaris/javadoc.html

http://barney.gonzaga.edu/java/tooldocs/javadoc/standard-doclet.htm

For help if you get stuck:

http://forum.java.sun.com/

and

of course, right here: http://groups.google.com/

Google groups WILL give you your answers.

Sun Java forums give you answers within a day or two but you have to
register (2-minute process, but well worth it - once people start
knowing you, you get more and more help - you get help even if you are
new - that is what forums are for!)

--

Thanks in Advance...
IchBin, Pocono Lake, Pa, USA

http://weconsultants.servebeer.com/JHackerAppManager

_______________ _______________ _______________ _______________ ______________

'If there is one, Knowledge is the "Fountain of Youth"'
-William E. Taylor, Regular Guy (1952-)

Starting University COSC and learning JAVA, advice please :D

Starting University COSC and learning JAVA, advice please :D

Comment