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Index ‹ java-programmer
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- 1
- Constraints in JPA (using Hibernate)Hi,
I have some @Entitys in JPA with Hibernate which create the following
relationship:
Brand 1<->* User
User 1<->* CreditCard
(where 1<->* means a bidirectional one-many relationship)
I want to be able to put a constraint on the CreditCard entity such
that the field CreditCard.CreditCardNumber is unique for a particular
Brand.
Without adding a reference to Brand in the CreditCard entity, is there
a way that I can achieve this?
Thanks in advance for any pointers!
Rich
- 2
- Not debugging?Phlip wrote:
>
> Duane Bozarth wrote:
>
> >> The define "legacy" as "requires debugging".
> >
> > That's a bizarre (at best) definition of "legacy"...
>
> That's why Greg didn't understand why I used it like that.
I didn't either (and still don't) because it has nothing whatsoever to
to w/ "legacy" or not...
> Me: Strive to never debug.
>
> Greg: What about blah blah blah.
>
> Me: You are using something that you can't design
> fresh from scratch to resist bugs. So you must
> run the debugger more often than greenfield code
>
> Greg: It's not "legacy" it's embedded blah blah blah
In that sense everything is "legacy" -- I can't redesign a commercial
compiler, either.
...
> Just don't leave the emulator out of the loop. Greg implied using it would
> slow down the tail end of development.
At some point in most embedded systems, that <is> true...you get to a
point at which the depth of emulation required isn't worth the effort
that would be required. Once at that point, reverting is rarely
productive use of resources.
- 2
- benchmarks? java vs .netOn Tue, 03 Jun 2008 16:18:34 +0100, Jon Harrop <email***@***.com>
wrote:
>There is no merit in comparing unoptimized code on .NET with optimized Java.
That's why posted it here so you can "optimize it". You fixed
mandelbrot but C# is still twice slower in three other benchmarks:
binarytrees
(the command line argument should be -server -Xms64m binarytrees)
http://shootout.alioth.debian.org/gp4sandbox/benchmark.php?test=binarytrees&lang=javaxx&id=2
vs
http://shootout.alioth.debian.org/gp4sandbox/benchmark.php?test=binarytrees&lang=csharp&id=0
revcomp
http://shootout.alioth.debian.org/gp4sandbox/benchmark.php?test=revcomp&lang=javaxx&id=4
vs
http://shootout.alioth.debian.org/gp4sandbox/benchmark.php?test=revcomp&lang=csharp&id=2
sumcol
http://shootout.alioth.debian.org/gp4sandbox/benchmark.php?test=sumcol&lang=javaxx&id=4
vs
http://shootout.alioth.debian.org/gp4sandbox/benchmark.php?test=sumcol&lang=csharp&id=0
also, C# significantly slower in recursion
http://shootout.alioth.debian.org/gp4sandbox/benchmark.php?test=recursive&lang=javaxx&id=0
vs
http://shootout.alioth.debian.org/gp4sandbox/benchmark.php?test=recursive&lang=csharp&id=0
>I have seen is on the Mersenne Twister PRNG where Java is 2x slower than .NET.
Post the benchmark. Let me see...
- 3
- java.lang.NoClassDefFoundError: org/aspectj/lang/SignatureHi,
Can anyone help me for this exception which I am getting whil trying to
conenct to MYSQL server thru TOMCAT.
Thanks
Maneesh
org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver
class 'com.mysql.jdbc.Driver', cause:
java.lang.NoClassDefFoundError: org/aspectj/lang/Signature
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at
org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:730)
at
org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:518)
at foo.DBTest.init(DBTest.java:23)
at org.apache.jsp.test_jsp._jspService(test_jsp.java:51)
at
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:210)
at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
at
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2422)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:163)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at
org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:199)
at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:828)
at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:700)
at
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:584)
at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
at java.lang.Thread.run(Thread.java:595)
- 3
- Question about help systemIs there a quick way to find out information about a particular method when
one doesn't remember to which class it belongs?
Thaks
- 5
- Why braces around try/catch?In article <3f3393b6$0$150$email***@***.com>,
Jos A. Horsmeier <email***@***.com> wrote:
>
>I beg to differ; catch clauses are optional as in --
>
> try {
> // some statements making
> // up the statement block
> }
> // no catch
I'm not sure what you mean. If I compile the above I will get a
compile error along the lines of
'try' without 'catch' or 'finally'
Cheers
Bent D
--
Bent Dalager - email***@***.com - http://www.pvv.org/~bcd
powered by emacs
- 6
- algorithm - how to estimate time to completeNot a problem as such, just a question about estimating time for producing
algorithms.
I recently had to write a class with a method that was to convert digits
(int) into their 'word' representation.
To begin with, converting say, 234, into "two three four", was easy enough.
But the method was also to 'sound english'
So, 234 now had to be converted to:
"two hundred and thirty four"
Some other examples:
"six million, three thousand and fifty six"
"six billion and one"
"eight billion,six million, three thousand, fourhundred and fifty six"
(like the way a person may write on a cheque underneath the digit amount.)
I wrote such a method. (which was actually a little more invoved than this
as it supports currencies, floating point number etc;) But, only after badly
underestimating the time involved for me to do so. There were were a few
elemenst about it that were not so obvious until I sat down to write it. I
ended up scratching a lot of stuff down on paper, and wrote it 3 times till
I was happy with it.
I have two questions here:
What is the best way to estimate time for rather small tasks like this? How
to you determine if a job will take an hour, a day, or a week? I know it
seems like a silly question - but I am just keen to see what sort of
responses come back from it.
Secondly, how long do you think it would take you to write a method such as
this? Personally, I allowed an hour and a half, and, like I said, was badly
mistaken. I know I took longer because I trivialised the problems till I ran
into them in live code, but still, it took way longer than I expected. (It
took me a whole day and a bit of the next day)
TIA
- 6
- 7
- Multiple server access jdbc/servletIf I have an applet, which is donwloaded to the local machine from server
A, and calls a servlet on server B.....can that servlet, via JDBC, access a
database on server C, assuming each of server's A, B and C are on separate
machines with separate URLs ?
Thanks, Ike
- 8
- struts action quiestionHello,
I have a short question concerning struts action context stack. I have 3
views. View A, B and C
To view C, I can get from view A, or B. In view C I have button "BACK",
Whenever I click BACK button, I want to go back to page that called view C
(A od B).
Is there any way to do it (remember calling view), or I have to implement my
own context stack mechanizm ?
thank you,
fera
- 11
- [ANN] Scala 2.5.0-RC2 releasedWe are pleased to announce version 2.5.0-RC2 of the Scala distribution:
| Scala smoothly integrates features of object-oriented and |
| functional languages and is fully interoperable with Java |
It fixes several bugs found in RC1.
http://www.scala-lang.org/downloads/changes.html#v2.5.0-RC2
Other release candidates may follow this version depending
on bugs reported by the Scala community (no changes/additions,
only bug fixes!); the final release (aka. 2.5.0-final) is
planned in 1-2 weeks.
Bye
-- Stephane
- 11
- Portal Solutions for developersHello everyone,
For easy to use web clipping and application clipping tools and portal
development follow the link below:
http://clickmarks.com/solutions/portlet_solutions/portlet_factory.html
Cheers.
- 13
- hai dearhai friends,
"each day is a new adventure to dream search and discover"
www.goodhistory5.blogspot.com
- 14
- JSP Tomcat link directoryes from 2 projects, help pleaseHi Everyone,
I have 2 Tomcat jsp projects which use many common directoryes. I wont
the directory from the second project linked to a directory from the
first, so I can change files on a single place. When I use something
like $ln -s ../project1/visualization ./visualization
and then make request from mozilla I get the error The requested
resource (/visualization/grid.jsp) is not available.
Any ideas
- 14
- Castor XML Question: How to ignore wrapping elementsI have an xml file that looks something like:
<Response>
<Invoice>
<PrimaryKey>239</PrimaryKey>
<OrderTotal>5893.03</OrderTotal>
</Invoice
</Response>
I am trying to map <Invoice> to my Invoice.java class. How do you get
Castor to ignore the outer <Response> tag? I could always do
pre-processing, but I would like to know if it's possible to do this
in the mapping xml file.
Thanks,
Ankur
|
| Author |
Message |
eric.deshayes

|
Posted: 2005-4-27 20:43:00 |
Top |
java-programmer, jikes dependencies
Hi,
I try to find all the dependencies of a class file (which are the
class to recompile when I modify just one java file).
According to Jikes website, "C depends on D if and only if the
constant pool for C contains a reference to D".
So, for a particular class, E, I found with Jikes the following
dependencies :
A, B, C, D.
At the same time, I used the BCEL library from apache to have a look
at the constant pool and I just find references to the class A, B and
C.
The class C is a parameter of one method of my class E and the class C
implements the interface D.
I understand why the class E depends on the class D.
Is the Jikes assertion incomplete or should I understand "C depends on
D (and all its ancestor/interfaces) if and only if the constant pool
for C contains a reference to D" or maybe even "C depends on D (and
all its dependencies) if and only if the constant pool for C contains
a reference to D"??
Thanks for your help.
Eric Deshayes
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Index ‹ java-programmer |
- Next
- 1
- Linking native libraries in Win2KHi there,
I'm trying to get some 3rd party "Kit" working and I'm struggling
with a java.lang.UnsatisfiedLinkError.
What I use is IBM's Visual Age 3.5.3 (JDK1.2.2) and the library in
question is IBM's OnDemand 7.1.0.7.
What I did was to copy all the DLLs and INIs etc. from the
"IBM\OnDemand Web Enablement Kit" into my WINNT\system32 folder -
where they should be found by any app, because it is listed in my
PATH.
However, I get an UnsatisfiedLinkError and I don't even know which
library it is actually looking for, as the stack trace
java.lang.UnsatisfiedLinkError
java.lang.Throwable()
java.lang.Error()
java.lang.LinkageError()
java.lang.UnsatisfiedLinkError()
int com.ibm.edms.od.ArsWWWInterface.initialize(java.lang.String,
int)
int com.ibm.edms.od.ArsWWWInterface.initialize(java.lang.String,
int)
int com.ibm.edms.od.ArsWWWInterface.init(java.lang.String, int)
void com.ibm.edms.od.ODServer.initialize(java.lang.String,
java.lang.String)
does not really help and I found when trying to catch this and dump
the name of the library was "null".
I somehow can't believe I'm the first one to struggle with this.
Any help is greatly appreciated.
Thanks,
Martin
- 2
- Street address parsing APIDoes any one know any Java API package that can parse/de-compose a
street address string into detailed components? For example:
----------------------------------
Example #1:
Input: 123 E Main St., Atlanta, GA 01234
output:
Street Number: 123
Street Pre-Direction: E
Street Name: Main
Street Suffix: St
City: Atlanta
Zip: 01234
-----------------------------------------------
Example #2:
Input: #3 Allen Court, 45 Main St. Boston, MA 02345
Output:
Apartment #: 3
Apartment/Building name: Aleen Court
Street Number: 45
Street Pre-Direction:
Street Name: Main
Street Suffix: St
City: Boston
Zip: 02345
--------------------------------------------------
Thanks you.
- 3
- focus gained received twice for the same buttonI have two buttons in a JPanel (default FlowLayout), which is nested in a
BorderLaout panel's SOUTH slot. The panel implements a FocusListener, and
I'm using the focus gained event to as follows:
/**
* 1) To ensure the next widget, if it has selectable contents (i.e.,
like a JTextField),
* has it's content completely selected.
* 2) To update the status bar with any tool tip text.
*
* @param event
*/
public void focusGained(FocusEvent event)
{
Component c = event.getComponent();
// debug
getStatusHandler().setStatus(c.getClass().getName());
// displayToolTipText( (JComponent) c);
if(c instanceof JTextField) {
((JTextField) c).selectAll();
}
}
For some reason, when the last button in the panel has the focus, it takes
two tabs to get it off. While there is no visual indication after the first
tab as to where the focus is, the debug trace I put in is displaying that
the Component in the focusGained method is still a JButton. The only
modification I made to the KeyboardFocusManager is to add the ENTER & shift
ENTER keys to the forward and backward traversal keys.
Thanks in advance,
- Eric
- 4
- (J2ME) CLDC1.0 and equalsIgnoreCase?When I try to compile a class using this method under WTK2.5 with a
CLDC1.0 target, I get:
cannot find symbol
symbol : method equalsIgnoreCase(java.lang.String)
location: class java.lang.String
The source compiles fine under JRE 1.5 and I can't see any mention
that equalsIgnoreCase was only added in CLDC1.1. Is the method not
available or am I doing something wrong? Thanks.
- 5
- addRow error when further editing is doneHi All,
Quick question (hopefully an easy answer).
Using JBuilderX--a GUI with a JTable component, I click a button
calling a method that adds a new row to a TableDataSet table in the
Database. This code in a datamodule class method:
openIMTable();
DataRow item = new DataRow(imTable);
item.setString("COLUMN1", "SOME TEXT");
imTable.addRow(item);
Returning to the GUI, the row is visually added, everything is fine.
The new row is highlighted in the JdbTable component. I click on an
empty column field in the new row and type some info--press Enter and
get the following error message: "Unable to set value because could
not post or leave row 0". If I select a different row with the mouse
and then reselect the "new" row I can add other fields with no
problem.
What am I missing?
TIA
Mark
- 6
- "error: cannot read:" (use the list file name written in a file)Hello:
When I compile the java source using command
javac javatest\kernel\*.java
it's perfectly work
but I have a lot of source code and distribute over many directories
So I write a file that contains:
javatest\data\*.java
javatest\kernel\*.java
...
names this file as "makefile.txt"
and use the command
javac @makefile.txt
but I got a error
error: cannot read: javatest\data\*.java
please help me
Eric Chen
- 7
- How to get line number of current cursor?I try to get the line number of current that cursor is on from the
JEditorPane.
I found method getSelectionStart() and getSelectedText(), but it not
has the getSelectedLine() or ...
So, anyone know how to get the current line number that cursor is on.
Thanks.
- 8
- IDE for JFSWhat IDE you would recommend for JSF based J2EE development using JBOSS
AS.?
- 9
- constructor inheritance/overriding?If I have a base class with some over-loaded constructors
that perform significant work before calling the
"main" constructor, what is the best way of achieveing
the same set of constructors in a sub-class?
e.g.
class B {
B(A a) {
... lots of stuff ...
}
B(D d) {
this(get an A from the d);
}
B(S s) {
this(get an A from the s);
}
}
class E extends B {
E(A a) {
super(a);
addition 'E' specific code
}
}
How do I implement E(D d), and E(S s)?
As I understand things, constructors are not inherited (unlike C++),
so I do need an explicit implementation of each constructor. But the
"obvious" minimal implementation:
E(D d) {
super(d);
}
would call B(D d), which would then call B(A a).
Thus the extra 'E' specific code would NOT be called.
I don't (unless I must) want to expose the inner workings
of the other constructors in 'B', for reasons of data hiding
and code maintainance.
This question must have arisen before, but my googling failed
me.
Anyone have a solution?
BugBear
- 10
- How to start default browser when clicking on a labelHi,
I was wondering how I can implement a JLabel that references to a http link.
When I click that label the default browser should open and loading the webpage.
This is for a JDialog 'About' window.
I've seen this several times, but I've no idea how to implement this with
Java/Swing.
Regards,
Helmut
- 11
- Improving Jmeter - User Agent Switching for HTTPHello Testers
Many current dynamic WEB systems with XML/XSLT can customize page
output by detecting what type of user is accessing page. It can be
recognition of IE and FIREFOX, plain text page for PDA or no javascript
menu for search engine. Because this different templates have different
resource needs for correct testing is neccesery to implement EASY WAY
to change/define User Agent Switching in Jmeter.
---------- Implementation Notes ------------------------
1. Allow Custom User Agent
Be shure then we can change user agent strings in both HTTP probes by
adding User aggent header in current custom hedaer module.
2. Impelemnt changing by GUI
Chris Pederik author of "User Agent switcher" for Firefox and Mozilla
agreed to share with us logic for generating various user agent headres
emulating different Web browsers and utilites.
Code is in Javascript and XML under at
http://www.chrispederick.com/
There is also contact infos for Chris.
---------------------------------------------------------
The best actual source of warious user agent strings is:
User agent Strings
http://www.pgts.com.au/pgtsj/pgtsj0208c.html
List of Robot Agent Strings:
http://www.pgts.com.au/pgtsj/pgtsj0208d.html
Ing Rudolf Kutina
Practical tester
Prague
Reply
- 12
- A bafflement moment on enumI have written enum code that works, but suddenly I had a sinking
feeling that it has no business working. I did a little disassembling
and sorted out the mystery.
let's say I create an enum with method next().
Then I override the next() method with custom code in the various
enum constants.
These methods live in anonymous inner classes of the enum (though
oddly they decompile as static).
Then I do something like this:
Breed d = Breed.DALMATIAN;
d.next();
How on earth does Java know to use DALMATIAN.next() rather than
Breed.next()?
The answer is that d contains a reference to the DALMATIAN inner class
that EXTENDS the Breed enum class as well as being an inner class of
it. So the next() method overrides the one in the Breed class.
--
Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.
- 13
- Users onlineHi,
How can I keep track of users online in a non web j2ee aplication.?
I thought using a Statefull EJB , one for each user created when the user
login and destroyed when he logs out.
Another option is to keep a table in the DB tracking this , maybe a CMP ?
Any sugestion ?
Thank you
- 14
- exe within a jar fileI want to package and run an exe within an executable jar file. I've
tried using the getClass().getResource("relative/exe/location"), but
receive the following error when running the jar
java.io.IOException: CreateProcess:
jar:file:\E:\test\TestProgram.jar!\myexe.exe error=2
this occurs when I run the following code:
Runtime rt = Runtime.getRuntime();
Process proc =
rt.exec(this.getClass().getResource("/myexe.exe").toString());
I would appreciate any help or suggestions on the subject. We've
considered extracting it an running it from a temp location and
cleaning up the directory, but we would like to avoid this. Thanks!
- 15
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