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Index ‹ java-programmer
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- 1
- Assignment Linked List HelpCan some please implement a class called MyList to finish this off?
public class MyList<E extends Comparable<E>> extends List<E> {
}
----------------------------------------------------------------------------------------------------
It must be implemented with this List.java:
public abstract class List<E extends Comparable<E>> {
protected class Node<T extends Comparable<T>> {
protected Node(T data) {
this.data = data;
}
protected T data;
protected Node<T> next;
}
public abstract void insert(int index, E data) throws ListException;
public boolean isEmpty() { return head == null; }
public abstract E remove(int index) throws ListException;
public void reverse() { head = reverse(head, null); }
protected abstract Node<E> reverse(Node<E> curr, Node<E> prev);
public abstract int search(E data) throws ListException;
public int size() { return size; }
protected Node<E> head;
protected int size;
}
I need help for this assignment ......
Thanks...
- 2
- Eclipse + Tomcat plugin: problem with automatic class reloadingHi all,
I am having a problem using the DevLoader that comes with the eclipse
plugin for Tomcat from sysdeo.
It is loading classes okay from locations.
But it is not reloading them when they change.
The reloading works okay for a class that is WEB-INF/classes.
Here are the details:
Versions:
eclipse version 2.1.1
eclipse Tomcat plugin V 2.2.1
Tomcat version 4.1.29
JDK 1.3.1_04
I have extracted the DevLoader zip into [Tomcat Home]/server/classes
directory.
The tomcat server is using this DevLoader to load the classes.
I set the debug level in my web-app Context in conf/server.xml for the
loader to 4.
(<Loader className="org.apache.catalina.loader.DevLoader"
reloadable="true" debug="4"/> )
Logging is redirected to the console.
I can see output in the console that shows that it added my classes
location:
[DevLoader] added file:/C:/dev/workspace/Test/classes/
This is the location to find a class ims.test.TestServlet.
And it is able to find this class:
WebappClassLoader: loadClass(ims.test.TestServlet, false)
WebappClassLoader: Searching local repositories
WebappClassLoader: findClass(ims.test.TestServlet)
WebappClassLoader: findClassInternal(ims.test.TestServlet)
WebappClassLoader: loadClass(javax.servlet.http.HttpServlet, false)
WebappClassLoader: Delegating to parent classloader
WebappClassLoader: Loading class from parent
WebappClassLoader: Returning class class ims.test.TestServlet
WebappClassLoader: Loaded by WebappClassLoader
available:
delegate: false
repositories:
/WEB-INF/classes/
required:
I find it strange that my location
(file:/C:/dev/workspace/Test/classes/) is under the repositories.
If change the code (recompile) ims.test.TestServlet it is NOT
reloaded.
However, if I have a class that is to be found in WEB-INF/classes
e.g. I have a different class ims.TestServlet that is in
WEB-INF/classes/
WebappClassLoader: loadClass(ims.TestServlet, false)
WebappClassLoader: Searching local repositories
WebappClassLoader: findClass(ims.TestServlet)
WebappClassLoader: findClassInternal(ims.TestServlet)
WebappClassLoader: Returning class class ims.TestServlet
WebappClassLoader: Loaded by WebappClassLoader
available:
delegate: false
repositories:
/WEB-INF/classes/
required:
Then if I change ims.TestServlet it IS reloaded.
WebappClassLoader: Resource '/WEB-INF/classes/ims/TestServlet.class'
was modified; Date is now: Tue Dec 23 10:33:32 GMT 2003 Was: Tue Dec
23 09:28:57 GMT 2003
thank you for any help you can give,
and best wishes for Christmas + the New Year,
Grainne Coghlan
- 3
- 5
- Teaching Children (was Re: Help, where to start learning Java)"Roedy Green" <email***@***.com> wrote in
message news:email***@***.com...
> I was lead counselor at a computer summer camp. I interviewed all the
> kids and discovered most of them wanted more than anything to write
> their own video games. There were programming novices. But within a
> week nearly every kid had written a game or animation. I was utterly
> blown away how fast they learned. In the breaks they DEMANDED to learn
> trigonometry, which blew the mind of a math prof who was watching the
> production.
>
> The other thing was the kids wrote nothing but commented/structured
> code. They never saw anything else, so it never occurred to them to
> do other wise.
Now this I didn't realize.
I had no idea you had experience in teaching children? I have been
looking for ideas to teach and stimulate desire to learn logic and
mathmatics in younger children. It is my belief that subjects which are
typically reserved for higher education such as trig, calculus, discrete
math, deductive logic could all be started before children ever leave
elementary. The trick would only be to interest the children, and present
the material in a way that it could be absorbed.
Can you offer any insight into this matter? Into teaching children how to
make games? What engine did you use (I suppose you were using Java).
--
LTP
:)
- 5
- why "synchronized" with wait/notify ?I know the language requires it and what exaclty happens with
wait/notify.
BUT it appears that the whole wait notify protocol should work just as
well without acquiring a monitor lock on the target object...
I've read something about why we need to have a thread own a monitor on
the object (key) that is waiting on, something about race condition.
but icant wrap my head around it, could someone care to walk me through
it please using a scenario where it would not work as expected.
So why would this not work (logic- forget the illegal monitor state
execption)
ThreadA
|
|
key.wait() //suspend threadA and add to waitset of key
ThreadB
|
|
key.notifyAlll; //Wake up one of the threads in the waitset of key
Thanks
- 5
- [JSF] How to determine the WEB-INF path of the current web application?Hello everybody,
I'm new to the Java world writing my first Java web application with JSF 1.1
and Tomcat 5.5. I have the following problem:
I've created a Properties file and placed it in the WEB-INF directory of the
web application. The file contains several configuration options like
database parameters. I want to open this file within my web application
with a FileInputStream which I pass to the load() method of a Properties
object. Unfortunately I was unable to determine the path of the WEB-INF
directory of the current web application. I don't want to write the path
hard coded into the source code.
Maybe my way is not the correct "Java way" of solving this kind of problem
so I'm not only interested in an answer to my question but also in
suggestions how to solve this problem in a better way.
Thank you!
--
Sincerely
Sven Jacobs
- 9
- Store XML to databaseI have some details from a jsp page, that i will store in XML format,
using DOM. I have created this much and now i want to store this XML
file in the database. How to do this ? the xml is available as a stream
in my program.
help of any kind is appreciated
thanks in advance..
sarath
- 10
- traversing through arraysSuppose I've got the following code
public class EmployeeData
{
public static void main(String [] args)
{
String [] [] employeeInfo = { { "Alex" ,"Joe" , "James" , "Tom"}
,
{" Manager" , "Clerk" , "Analyst"
,"Manager"} };
double[] salary = { 2000 ,540 , 6321 ,1999.99};
// how do I traverse through that multidimensional array to display the
employee name and title and those who earn more than 2000
// I was trying to use a for loop ( int i = 0 ; i< employeeInfo.length ;
++i)
then use the if statement but it doesnot work ,
Anyone can help me on this problem
thanks
boen
- 11
- problem with methods on a bound classHi,
I've been fiddling around with JavaScript.pm, which is very cool, I have to
say, I've bound a class, and sucessfully bound an object, and i can read
from the object's properties, and execute it's getter/setter functions, but
for some reason i cannot get the object's methods to work..
here's a cleaned up version of what i've been testing with:
$js->bind_class(
name=>'Foo',
methods=>{
test => \&Foo::test
},
properties=>{
testy =>{
flags => JS_PROP_READONLY | JS_PROP_ACCESSOR,
getter => \&Foo::test_getter,
}
}
);
my $obj = new Foo();
$js->bind_object('obj', $obj)
(where package Foo has a 'test' method)
....
now in js: 'obj.testy' (the property) works fine, but 'obj.test()' (method)
just doesn't.. there seems to be no indication that it's successfully bound
(everything just says it's not defined).. getters and setters work, but
methods just don't seem to..
Any clues as to what's going on?
Dan
- 12
- About JEditorPaneI wrote a plugin to NetBeans 5.0 which displays html pages in a
JEditorPane, when i clicked a file in explorer.
JEditorPane is in the topcomponent class.Also JTree(Explorer) in a
other topcomponent class.
I use setPage(URL url) method. But its not working properly.That means
the editor pane displays the html code of the file
But i wrote it as standalone application, it displays correctly.
Explain what is the problem here.
- 12
- Tomcat & SSL & a certificate generated by VerisignAttempting to SSL enable tomcat 4.04. Have implemented JSSE and SSL
works fine when I create a keystore with a self generated certificate.
keytool -genkey -alias tomcat -keyalg RSA -keystore .keystore
We now want to cutover using a production certificate. We create a
.cer file by accessing our production web site and export the
certificate to a .cer file.
then using the keytool we import the .cer file
keytool -v -import -file prod.cer -keystore .keystore
When we inspect the .keystore file using the -list switch we see the
certificate.
Now when we implement the .keystore in tomcat, only the original self
generated certificate is presented.
So, using the keytool we delete the original self generated
certificate so we are only left with the newly imported production
certificate.
When we implement this .keystore file with only the production cert,
the browser and tomcat fail to negotiate. Tomcat binds to port 8843
but the ssl negotiation is hosed.
Has anybody ever gottent tomcat & ssl to work with a non self
generated certificate? Can you please help?
Thanks,
email***@***.com
- 12
- Getting ResultSet From Cursor Too SlowAll,
I have a method that calls an Oracle Stored Procedure from an Oracle
Package. Everything works fine but the last two lines in my code below
where I get the Cursor from the procedure and cast it to a ResultSet is
a huge bottleneck. Does anyone have any ideas on how to make this
transition faster for large resultSets?
Thanks in advance.
Corey
ResultSet rs = null;
Result r = null;
String sql = "{call SECINQ.GetUsersBasic(?, ?, ?, ?, ?, ?, ?, ?," +
"?, ?, ?, ?, ?, ?, ?, ?," +
"?, ?, ?, ?, ?, ?, ?, ?," +
"?, ?, ?, ?, ?, ?, ?, ?, ?)}";
open();
CallableStatement call = (CallableStatement)con.prepareCall(sql);
call.registerOutParameter(1, OracleTypes.CURSOR);
call.setString(2, name1);
call.setString(3, name2);
call.setString(4, name3);
call.setString(5, name4);
call.setString(6, geid1);
call.setString(7, geid2);
call.setString(8, geid3);
call.setString(9, geid4);
call.setString(10, ssn1);
call.setString(11, ssn2);
call.setString(12, ssn3);
call.setString(13, ssn4);
call.setString(14, userId1.toUpperCase());
call.setString(15, userId2.toUpperCase());
call.setString(16, userId3.toUpperCase());
call.setString(17, userId4.toUpperCase());
call.setString(18, userId1.toLowerCase());
call.setString(19, userId2.toLowerCase());
call.setString(20, userId3.toLowerCase());
call.setString(21, userId4.toLowerCase());
call.setString(22, userId1);
call.setString(23, userId2);
call.setString(24, userId3);
call.setString(25, userId4);
call.setString(26, phone1);
call.setString(27, phone2);
call.setString(28, phone3);
call.setString(29, phone4);
call.setString(30, flName1);
call.setString(31, flName2);
call.setString(32, flName3);
call.setString(33, flName4);
call.setFetchSize(200);
call.execute();
rs = (ResultSet)call.getObject(1);
r = ResultSupport.toResult(rs);
- 15
- Kodak v Sun; patent law gone all wrong?If in 1995 Sun Microsystems, Inc. changed the name of OAK to Java and
modified the code for the Internet, how did Sun infringe the patents
Kodak acquired from 'Wang' in 1997? What damning evidence did Kodak have
that in 1995, Sun incorporated the 'Khoyi' method, thereby infringed the
patents?
The "Khoyi patents", named after Dana Khoyi - an ex-Wang engineer,
"covered a method by which a program can get help from another computer
application to complete a task", which they claim is the way Java
operates and that Sun has therefore infringed the Khoyi patents..
Whose intellectual property is Java? Surely Java was patented in 1995,
just after the change? Were the Wang 'Khoyi' patents and Sun 'Java'
patents identical? I take it Wang patented their software years before
Sun did? Does anyone know what year?
If the two were identical or similar, isn't it possible that in a world
of 6,395,379,218 people, it is more than likely that two or more people
might have the same ideas? I find it difficult to believe that Sun
infringed Kodak's patents, but rather that Kodak got a little too
desperate given it's not doing so well in this 'digital' age and had to
lay off some 15,000 jobs worldwide a month ago "because of declining
demand for consumer film and colour photographic paper"..
How on earth can an eight member jury of lay people understand "patent
law" to deliberate and find in favour of Kodak? I don't understand how a
jury could possibly fathom the complexities of patent law, without any
background or education in the legal arena, and find in Kodak's favour?
There are a lot of questions that I have to things that don't add up,
like; Java is freely downloadable, so how can any jury find in favour of
Kodak who wanted damages of $1.06 billion in past royalties??
How did Kodak prove that Sun had access to its patents?
If Kodak is so sure that Sun infringed patents, why did it bother to
agree to the $92 million settlement? Surely they believed they would be
awarded $1.06 billion or even more..? accepting such a small amount (for
them) is silly, it sounds to me like they thought they wouldn't win..
This case is a perfect example why juries should NOT be involved in
patent suits.
Sun should not have settled the case, it should have seen the case
through and appealed the prospective travesty of justice..
Does anyone agree with me here? I'd be interested in other people's
opinions on this issue. A public debate, anyone?
- 15
- Java developer needed (Open Source project)Java developer needed, pref. with socket prog exp
---------------------------------------------------
Programming Language :: Java Competent 6 Mo - 2 yr
Socket programming(Java):: Want to learn < 6 Months
Project page: http://freelancebot.sourceforge.net/
- 15
- Switch on StringsHello, I have code that looks like this:
switch(myColor){
case "blue":
{
this.setForeground(Color.blue);
break;
}
case "red":
{
this.setForeground(Color.red);
break;
}
case "green":
{
this.setForeground(Color.green);
break;
}
default:
{
this.setForeground(Color.blue);
}
}
myColor is a String being read in from an HTML file PARAM line.
The above code doesn't work, because switch doesn't work with strings.
So I was wondering how else I can do this...
ttyl
|
| Author |
Message |
nprabhakaran
|
 Posted: 2007-3-19 12:51:00 |
Top |
java-programmer, Mail API
i wrote program for sending mail from one server to another but while
comile time it shows an error like Mail API is not found.. i was
downloaded it from sun..but i dont know where to install this API..so,
can u please tell me...?
|
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|
| |
|
Phi
|
| Posted: 2007-3-19 20:03:00 |
Top |
java-programmer >> Mail API
email***@***.com wrote:
> i wrote program for sending mail from one server to another but while
> comile time it shows an error like Mail API is not found.. i was
> downloaded it from sun..but i dont know where to install this API..so,
> can u please tell me...?
>
Have you downloaded both: activation.jar and mail.jar?
"activation.jar" and "mail.jar" must be in your classpath:
java -cp .:activation.jar:mail.jar YourClass
greets
phi
|
| |
|
| |
|
Arne Vajh鴍
|
| Posted: 2007-3-19 20:57:00 |
Top |
java-programmer >> Mail API
email***@***.com wrote:
> i wrote program for sending mail from one server to another but while
> comile time it shows an error like Mail API is not found.. i was
> downloaded it from sun..but i dont know where to install this API..so,
> can u please tell me...?
It does not matter where they are installed.
They just need to be in the class path.
And since you should set that explicit, then no problem.
Arne
|
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Index ‹ java-programmer |
- Next
- 1
- Mono .netRecently I learned that Mono .net will run MS .net applications. This
came as a bit of a suprise to me because I thought Mono was a different
implenteation of .net and therefore incompatible.
So this raises some interesting questions. Since Microsoft still
retains copyrights and patents to .net is Mono .net governed by the
MSDN EULA. Or can Microsoft revoke the license to the ECMA at a future
date. If that were possible it would not seem inconcievable that
Microsoft could theaten to withdraw if they did not agree to adhere to
a MS EULA. On the otherhand Microsoft could demand a fee for each
transaction. Awhile back Bill Gates said that Microsoft was not making
enough money from the internet and wanted to use .NET as a chargeback
mechanism to force them to pay 1 penny for each transaction.
Alternatively speaking however Mono .NET could be used as a migration
platform to move people to Linux. One possible advanate to Mono .NET is
that SE Linux gives the administrator more granularity to lock down the
OS.
In any case there is a lot to ponder.
- 2
- Eclipse Internal Web Browser option disabledI am using Eclipse 3.1.1 for some reason
Window->Preferences->General->Web Browser does not allow me to select
the "Use internal Web browser" option. Only "Use external Web browser"
underneath which nothing is listed. How do I enable or install the
internal web browser? The radio check box is currently disabled.
Thanks in advance.
JM
- 3
- getBytes() returning too much dataHi,
I'm running postgreSQL 7.2.1 and java se version 1.4.0_01
I'm storing some images in the database as bytea. When I use
result.getBytes() to fetch the data back it ends up being a larger
size than that which is stored in the database. (I'm sure that the
value stored in the database is the correct size) I was testing it out
with a single entry in the table like this: -
rs = stmt.executeQuery("SELECT imageid, name, gender, image,
length(image) FROM images");
And tried this: -
System.out.println(rs.getInt(5));
byte[] imgBytes = new byte[rs.getInt(5)];
imgBytes = rs.getBytes(4);
System.out.println(imgBytes.length);
Even in this case where the first println displays the expected output
the imgBytes array somehow ends up being about 10k too big (the size
increase is consistent)
Does anyone have any idea whats going on and how I might fix it?
Thanks,
Conor
- 4
- Getting images in appletI have an applet that reads jpg's. It works in AppletViewer but I get a
permission block for reading the file when I load it in my browser (all the
files in this case are local). How would I get permissions for it it to run
in a browser, and what would I need to do if I were to upload this to a
website?
- 5
- jsp grid creationi want to use a grid in my front end using java. in this grid i want to
fetch the information from the database. can i make such a grid using
jsp.
if yes, can anybody tell me how?
ashutosh
- 6
- How to make a s/w producthi,
I am having some JAVA Applets which will simulate a mechanical
Engineering Lab Set Up. I want to make this as a software Product which
is having some set up files and Register Variables etc.. I want to make
this as an evaluation copy for a particular period of time and a full
fledged software also. Can any one tell me how to make this and the
requirements for doing this.
Thanks in advance,
sarath
- 7
- 2d String in a BoxHi,
I want to draw a string of varying size inside a box.
g.drawString("........string....", x, y)
g.drawBox(x, y, w, h);
-------
|String| h
-------
w
Is there a good way to calculate the size of the box?
- 8
- Help with XtagsI am using jakarta's xtags library. I have put the xtags.tld file
unser /WEB-INF and the taglibs-xtags.jar in the /WEB-INF in the lib
directory. I am using
java version 1.4.2-b28 and tomcat 4.1. IN my jsp i use the following
tags
<xtags:style xml="/test.xml" xsl="/article-html.xsl"/>
when i run the jsp, i do not get anything ..blank page... Rethere some
file i am missing...
any help would be appreciated.
THanks
Mohit
- 9
- Dates in a sql StatementHello,
I have the following sql statement:
SELECT code,fname,lname FROM employee WHERE datestarted = '02/12/2001'
This works fine when executed through dbaccess, but when I use JDBC to get a
ResultSet nothing is returned.
I am using JDBC.2.21.JC5, my back end eis is Informix Universal server.
Also, the query executes fine when I remove the date part:
SELECT code,fname,lname FROM employee
Can any one tell me what am I doing wrong since I am new to JDBC.
Thanks in advance.
-r
- 10
- RedHat9 + Sun JDK 1.4.2_1 + NPTL = issuesThis is a multi-part message in MIME format.
Hi,
These 2 newsgroups (redhat.kernel.general, comp.lang.java.programmer)
seem like the apropriate place for my contemplations, if I'm at the
wrong place please direct me to the right one.
I'm trying to get as many Java threads as possible running on my Linux
box. Using RedHat 7.2 (2.4.18-24.7.xsmp) and with the right JVM (Sun
1.4.2_1) parameters (-Xss, -Xms, -Xmx) I have a fairly stable production
system that will scale up to 800 threads without significant problems.
This however is not enough for me on the long run.
I'm a loyal reader of The Volano Report [http://www.volano.com/report/]
and The C10K problem [http://www.kegel.com/c10k.html] for some time now
and after running across this victorious article about the latest JDK
and the NPTL in RedHat9
[http://developer.java.sun.com/developer/technicalArticles/JavaTechandLinux/RedHat/]
I thought that the scalability problem of Java on Linux was solved.
After some testing (see attached Test.java) I was disappointed to see
that after creating just a little under 3000 threads (that basically do
nothing) the JVM threw this dreaded "java.lang.OutOfMemoryError: unable
to create new native thread" exception again while 'free' still reports
loads of free memory. The -Xss, -Xms or -Xmx parameters to the JVM don't
seem to do anything for me (any parameter value still causes the
Exception at roughly 3000 threads).
What gives? The article about the new JVM with the new RedHat promises a
lot (eg. No limits on the number of threads), but when put into test
does not yet deliver. Do I need to tweak kernel parameters to allow for
more threads? If so, where do I do this?
For those that wonder why I need so many threads; I run a java HTTPD
where any request is a call to a servlet, each call needs a Thread. I
handle a lot of requests. For the CPU this is not an issue, the calls
are very thin. However, the Thread management in Linux does not seem to
be suitable for this kind of scaling (yet?).
I would be glad to come across someone with the same problem and other
views on this issue. I've been working with Java for more than 5 years,
starting on OS/2 and now using Linux as host OS. And my needs always
seem to just a tad ahead of the possibilities.
Sacha
- 11
- Open File componentThe usual file open component on a form consists of a label describing
the file, a text field that accepts a file name and a command button
that brings up a file chooser.
Is there a "standard" component that does this preferably a bean that
can be added to NetBeans?
- 12
- break removal
Let's say you have some code like this:
case 1:
if ( x )
if ( y )
return a;
else return b;
else return c;
break;
Jva will insist you take out the break because it is not needed.
then later you inadvertently meddle with the code say like this:
case 1:
if ( x )
if ( y )
return a;
else return c;
now you need the break back in there again, but of course Java wont't
tell you.
What is the best way to handle this to make sure you have covered all
possibilites and that you truly can't ever fall through?
You can't even put debug code in there to catch the problem. Java
will make you take it out if the prgram is CURRENTLY working.
--
Bush crime family lost/embezzled $3 trillion from Pentagon.
Complicit Bush-friendly media keeps mum. Rumsfeld confesses on video.
http://www.infowars.com/articles/us/mckinney_grills_rumsfeld.htm
Canadian Mind Products, Roedy Green.
See http://mindprod.com/iraq.html photos of Bush's war crimes
- 13
- Questions about code signing cert.Martin Chan wrote:
> 2. What will happen when if people use my application after my
> certificate has expired?
After the expiration date the certificate
cannot be used to sign applications.
The date has no implications for the execution
of already signed applications.
- 14
- 15
- getConnection in strutsHi,
I hope the question is addressed to the appropriate forum :)
First of all I'd like to say I'm new to struts. My question is how
should I getConnection to DB. I know how to read parameters for
connection but I'd like to make conections more robust. I mean I should
use ConnectionPool. I've some idea how to achieve it but..if I split my
application into tiers (presentation, conntroller, bo and dao) how can I
get Connection from DAO tier since I don't have access to server
context. I'm looking for some advice how to cope with such problems. Of
course I could pass in constructor these parameters but I don't think it
was good solution.
How did you solve problem with accessing db from your struts applications?
Rgs
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