I can't seem to find the right method to check if a URL exists (it's not
a HTTP 404).
InputStream input = url.OpenStream();
input = new BufferedInputStream(input);

In my Genetic Algorithm program, I have a class called Genome. Another
class called GA has a class variable called 'population' which is an array
of type Genome.
One of the methods in GA, called CreateNextGeneration(), creates a local

I'm developing an application using Java and I would like the user to
be able to plug in various methods of persistance.  The has led me to
JDBC using standard SQL-92, but this is really overkill for what I'm
trying to do.  I only have a handful of classes that I would like to

OK, this is somewhat of a neophyte question but I don't know where else
to ask it.
What is the best way to integrate existing Java classes into a web
page?  These are purely domain logic classes... no presentation or

If you make a call to the database.
If you cannot find any person with a matching last name, do you
a. Return null
b. Throw a RuntimeException

If I had this tag and wanted to return 123 how would I do it?   I have
tried countless methods but can not get the only the 123 without the
<TD> tags
<TD class=tblform3 id=L_listing width=23>123</TD>

Is it possible for an external program to send a signal (such as SIGINT,
SIGUSR1, SIGUSR2) to a java application, and have this java application
handle it?

Is it possible to start a JVM with -Xdebug -Xrunjdwp option so it
accepts both shared memory and socket connections? Or is it
one at a time?

When FTP'ing compiled class to another box I get the following error:
Exception in thread "main" java.lang.ClassFormatError: <classpath>
(Invalid pc in line number table)
       at java.lang.ClassLoader.defineClass0(Native Method)

Is it possible to have a servlet listen to a specified port?. Any
examples of how to do this (or links to examples) would be great.
I have not had much success having this question answered, or finding
examples when searching via Google.

How can I stop the tab key from switching components on a screen?

My application is something like this:
I have two files:
c:\test\a\b\JarTest.class
c:\test\c\d\JarMan.class

how likely is it that the following code produces duplicate ie
identical random numbers, when it gets executed on different virtual
machines running on different computers?
import java.util.Random;

I am new to struts and I have a small problem.
I have a bean (DataGrid) that has a collection of Columns (ArrayList)
and each column has rows (ArrayList). So, when i want to iterate with
the lists i would do something like:

I seem to have a problem that whenever I add arguments to my jnlp file
to be passed as parameters to the main method of the target
application, they all come out as null!
I'm passing three parameters, but the target application seems to