By the deadline
an original Java applet on a HTML web page with link to the source code.
I hope this will be public
and linked to your public web page. I expect the code to
include some thing original... and your page to have notes saying what is new
Start from with my exiisting Java and HTML samples.
You may have to take classes and extend them to do what
you'd like them to do. You can(probably will) implement existing interfaces and abstract
classes. Add comments indicating what you changed.
Study the examples and experiments below. Pick one.
Download the page and source
code into your working directory and make changes. When done
put the test page, the source code, and the compiled applet in
your public web site(below).
Find the index page and add a link to it to your Java page.
Your Public Web Site
Do not abuse this site by overloading it with large graphic and audio
files. It will be removed.
In this lab your public WWW site appears under a directory that looks like this:
/pool/web/public/your_group/your_name (in JBH358)
/web/public/your_group/your_name (in JBH359)or (sometimes)
/web/public/your_nameand your login (HOME) directory is called:
If you work directly in the public directory:
import ColoredText;does not seem to be compatible with all versions of Java. Very old and newer ones automatically import local classes so I had to make it into a comment:
//import ColoredText;You may hit a Java where it has to be uncommented.
Here is the same applet running only one thread: [ test.Spinner.html ]
Warning: close down and reopen your browser after running the second one above.
Prime Number Sieve
I have developed some examples of various kinds
of concurrency in Java and other languages using
Tony Hoare's Prime Number Sieve
[ Specification ]
You can see implementation in the UNIX shell, Ada, C, C++, Java, etc, in [ http://www.csci.csusb.edu/dick/cs320/sieve/ ]
Java has a nasty little flaw: it is inherently multithreaded.
On the other hand if you avoid Threads you tend to get blank
Worse several browsers do not allow you control of these thread. If you look at a page with an Applet that has a thread that doesn't stop itself it will continue running after you leave the page. Slowly and steadily as you view badly behaved applets your CPU gets full of things you can not see or control. The cursor flickers, and so on.
It would be unethical for me to show you a demonstration page! I have perpetrated this kind of problem in some of my code. The following shows a program that shows a blank when run as an application and grabs the CPU if run in a browser: [ Surat2.java ]
For more see, [ mbox ]
. . . . . . . . . ( end of section Concurrency) <<Contents | Index>>
You may need or want to do some sophisticated graphic interfaces
if so this experiment may help you.
A layout manager automagically places some graphic parts inside a larger graphic Container. Here is an example of some of the standard layouts.
By the way take note of the relation
instanceofin the CardTest code it allows Java to find out the type of an object at run time.
A Graphic Applet
Java is one of the few languages to provide the functionality needed
to graphics as part of its standard library. Previous languages have
left it up to others to create libraries for doing graphics. Dr.
Zemoudeh has a nice example of this in the Scribble applets and
applications. The source code for an application is in
[ StandaloneScribble.java ]
and the compiled byte-code file
[ Scribble.class ]
Try this out at
[ Scribble.html ]
Here is a page+applet that uses the Le Riche algorithm to plot
a curve. I've used the Henrici spiral as a test case.
[ test.RecursiveHenrici.html ]
Try it out and then modify the curve (leave Le Riche
Entropy and Randomness
Here is a page that demonstrates how to get Random Numbers
[ test.HowRandom.html ]
by painting 4000 random points. Here are a some more
[ test.Surat.html ]
that produce more or less random pointilist paintings.
George Seurat's real paintings are much better than these.
And his name is better when spelled write.
I'm still developing the following one. On some Browsers you have to reload to get the display to update:-) [ test.Surat4.html ]
The Crispy Program in Color
. . . . . . . . . ( end of section More Java) <<Contents | Index>>
The code includes a Makefile [ Makefile ] , to process that can be independently compiled, and run using a pipe to connect them ( p1 | p2 ): [ p1.c ] [ p2.c ]
It is easy to convert p2.c into a restartable function: [ p2s.c ] and so produce [ crypto.c ] or you can use the UNIX C pipe() and fork() functions [ cryptop.c ] to get two concurrent processes.
In Ada it is easy to create a main program [ crypto.ada ] that has a package with two tasks P1 and P2.
You might like to develop a Java translation of the original design.
. . . . . . . . . ( end of section Non-Java Concurrency) <<Contents | Index>>
. . . . . . . . . ( end of section CS620: Java Applets) <<Contents | Index>>