Programming :: Java : Use Dynamically Loaded Classes?

May 15, 2010

I'm new to Java.
I'm trying to use some dynamically loaded classes in my application.
The application doesn't know those classes , Just it try to load a class by name that its name came from input.
It doesn't know class (So I can't use casting) but just needs to call some methods of that class (every class should have that methods).
I thought about interfaces but I don't know how.
How can I call those methods?

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Programming :: Save / Load Data Segment Of Dynamically Loaded Shared Object Library?

Aug 25, 2010

Our application uses a dynamically loaded shared object library (codec library) to compress and decompress audio streams.

There happens to be several static and global variables in this shared object library. Hence it is not possible to process two interleaved unrelated media streams using this shared object codec library because each stream corrupts/changes the contents of these static/global variables.

Is there a way through which a context save (save contents of data segment of shared object) and a context load (load previously saved contents of data segment of shared object)operation can be performed on the shared object library. This way the context for each media stream can be saved and loaded before and after processing the "other" media stream respectively.

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Programming :: Reg: C++ Abstract Classes?

Oct 28, 2010

I know the basic answer about how to create a class as ABC.But I don;'t know- - why I have to create a AbstractBaseClass. - In what situations it can be example code base and not like a animal(base) and tiger(derived) relationship example.

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Programming :: C++Linking Classes/.cpp Files To Run One After Other?

Apr 11, 2010

This is probably a really stupid thing to ask considering the development I'm doing (effectivly creating a virus scanner), but how do I link classes/cpp files?I have 3 applications/sections that I can compile/combine with a makefile, that's fine, but I need them to run 1, 2, 3 once the output from the makefile is done.Currently the only section to actually run is whichever I have "main" in and obviously if I put that into all three, they won't compile as one.I've been looking all over the place at all sorts, header files and such, but there is no mention of how toually do this although I'm sure it must be possible. I'm used to being able to do this in Java and I'm sure I've seen C++ applications do it, but not worked out how.I have 3x .cpp files which are combined into one using a makefile:

# Virus Scanner
scanner.out : ProgramList.o MD5Hash.o HazardCheck.o


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Programming :: Possible To Have A Templated C++ Stl Containers In Classes?

Feb 15, 2010

Is it possible to have a templated c++ stl container in another class without specifying the type prior to compile time? I haven't coded in c++ in a while and im at a total loss.

For example - Not real code. Just outlining the problem code...

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Programming :: Saving A Certain Variable And Using It In All The Classes?

Feb 4, 2010

facing a problem in declaring variables. i have a few classes like the one below...

#ifndef _FINANCE_H


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Programming :: Child Classes That Extend Each Type Of Pet

Jan 6, 2011

I am fairly new to c++. There must be a better way to do the following?:- Say I have a base class, Pet. I have several child classes that extend from this, like Dog, Cat, Fish etc.

I have the following function, that returns a pointer to a new Pet:-
Code: Pet* addPetToVet()
{ //Do some stuff
return new Pet();
} This will return a pointer an instance of a pet object.

Now, if I want to interpret this pet as a dog or cat I have to do this:-
Code: Dog* dogA = static_cast<Dog*>(addPetToVet());
Cat* catA = static_cast<Cat*>(addPetToVet()); Is there a way around this? Casting seems lame. I cant write a function for each type of pet.

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Ubuntu :: Sun-Java-6-jre Installed But Openjdk Loaded

Oct 28, 2010

I have both the openjdk-6-jre and sun-java6-jre versions of java installed on my Ubuntu Maverick desktop, with the sun version setup as the default. I was trying to load the web page,URL..., an amateur radio software defined receiver. I can load the page on Firefox run on XP in a VirtualBox machine, but when loaded on Firefox on my Maverick desktop, I wasn't getting any sound with openjdk, so I installed sun's and set it as the default. When I run 'java -version' from the command line, it reports the following:Java(TM) SE Runtime Environment (build 1.6.0_22-b04)Java HotSpot(TM) Server VM (build 17.1-b03, mixed mode)but on firefox, when loading the above page, it reports 'java version test applet 1.6.0_20' on the page. How do I get sun's version to run? I need to get the sound to work.

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Programming :: [c++] Mixing Abstract Classes And Multiple Inheritance?

Apr 18, 2011

Why are the 'defense' method calls actually using the 'offense' methods.Also, is there a way to remove the commented base classes for 'Player' so that the casting isn't necessary?

#include <iostream>
class Offense


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Programming :: Equivalence Classes Based On Field Values And Multi-key Hashtable?

May 12, 2010

I've got a set of objects (all of the same type). I'm trying to think of a good way to divide it into equivalence classes, with equivalence of two objects defined as meaning a specified set of attributes are equal for both objects. More concretely, I've got:

- a Java class with around 50 fields
- a bunch of instances of the class

I want:

- to divide the instances into a few sets
- in each set, each instance has field 1 - field 5 equal to fields 1-5 of the other instances in the set.

The method I've come up with is to generate a hashcode for each instance based on the hashcodes of fields 1-5*, and map the hashcode to one of my sets. Ignoring problems with potential hashcode collisions (which I'm expecting to be too rare to worry about for now), does that sound reasonable? It seems simple enough, but I'm wondering if there's a simpler method I haven't thought of.

* I'll generate the hashcode using a method based on Eclipse's generic hashcode method, which looks like this:


public int hashCode() {
final int prime = 31;
int result = 1;


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Programming :: Dynamically Loading Libraries In GNU?

Oct 22, 2010

This post isn't really asking for a tutorial, but rather asking for some ideas. I've come up with a few ideas, but they seem cumbersome and unnecessary, so I was wondering if someone with more experience than me could out. Also, my explanations suck, but I'll try to do my best. So say I have an executable called X. At some point during its execution, X loads and uses (using dlopen and dlsym) a library called Y. In Y, there a bunch of functions that call the function called, for example, void *special_malloc (size_t). These functions come from another linked library (linked during compilation) called Z. Problem is, special_malloc contains some static variables within its scope, and when those variables are reset midway through a program, an invalid free occurs (special_malloc uses garbage collection). Now, what I want to happen is that whenever lib Z calls special_malloc, it instead calls the special_malloc defined in the executable X, so that these static variables are retained. Keep in mind that I have control of the Z library, meaning I can edit the source to fit my needs.

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Programming :: Bash - Read The Array Dynamically?

Sep 24, 2010


test=(1 2 3 4 5)
for car in ${test[@]}
echo "Element : $car"


if variable $car equals 1, new element is added "6" to an array. But i don't know why when i am printing all elements of this array (echo "Element : $car") this element ("6") is not mentioned, but if i make a command which check an amount of contained elements by array it will be 6 elements.

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Programming :: How To Call Array Dynamically Into Script?

Jul 20, 2011

I have a script which takes an array as an input to the file.ex: test.ksh -l <array_value>

Every time I dont get the same array name.EX: test.ksh -l x ; where x="a b"test.ksh -l y ; where y="c d"

I store the value I get in l in varaible myLvalue.Now indise my Script I want to run a for loop for thevalue I get in -l.If I write the for loop as below. I'm getting value x.However I'm expecting the loop to run for a and b.

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Programming :: Link One Library Statically Others Dynamically - Gcc - G++

Jul 6, 2011

I would like to make gcc to link one lib (pthread in the example) statically, and the rest dynamically.

(See the example .c file at the end of this post.)

compiles fine, but every lib is linked dynamically.

Now every lib is linked statically

Not a dynamic executable

I would like to link the libpthread statically and the rest dynamically. Is it possible?

[url]says if I give the full path to the .a lib then it will be linked statically:

So for me it does not work.

On other sites I found that I should use -Wl,-Bstatic -lpthread -Wl,-Bdynamic, but it also doesn't work:

So, how can I do that?

Machine: Linux #1 SMP Mon Jul 28 13:06:32 UTC 2008 i686 i686 i386 GNU/Linux SLED 10

As an example I used a little demo program from [url]

Here is the code:

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Programming :: Dynamically Supply Input To Netcat In A Script?

Mar 5, 2010

I am trying to write an irc bot to run interactive fiction games in a channel. I am connecting to the channel using nc. I'm having a hell of a time trying to supply input stdin for nc after the connection is established. Here's what's going on. I've got lines of plain text in a file with the irc commands required to identify the bot's ID and join the channel. I can connect easily using any of the following commands

cat inputfile | nc 6667 -i 1
nc 6667 -i 1 < inputfile
Named_Pipe | nc 6667 -i 1
cat inputfile > Named_Pipe

With the first two commands nc connects, reads the file with some time between each line allowing the irc server to respond, bringing me into the channel. It then begins to receive stdin from the command line allowing me to do things like "privmsg #channelname :Hello World!!!" sending messages to the room. This is not the desired behavior. I require nc to take additional stdin from the inputfile if I cat additional text to the end of it.

The last set of commands using the named pipe seem like it does the same, but it doesn't actually send anything to the room, which indicates to me that perhaps nc is continuing to take stdin from the named pipe (this is the desired behavior) rather than dropping to the console for stdin. If I try to cat more plain text data to the end of the named pipe, however, either with something like "echo 'privmsg #channelname :Hello World!!!' > Named_Pipe" (or >> instead of >) or with a filename in place of the "echo" command the whole command simply seems to hang until I press ctrl-C.

I don't understand what I'm doing wrong. With anonymous and named pipes, and with redirection, the problem seems to be the same. nc seems to take it's stdin from the file until it hits the end of file, at which point I can no longer introduce new lines of plain text as stdin for the running nc process.

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Programming :: Local Dynamically Allocated Array In Fortran?

Oct 19, 2009

I (my friend) have a fortran program with the code along the following lines:


REAL, DIMENSION(4000,4000) :: a, b, c

The problem is that the huge matrices are retained in memory even after the subroutine ends. Is there an easy way to declare the arrays in a sort of dynamic way, like they were in the following C example?


void ny(void) {
double a[4000,4000];

I mean in the C example the memory is released as soon ny() exits.

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Programming :: Get Path Of One Library To Link It Dynamically In Program?

Apr 28, 2010

I'd like to get path of one library to link it dynamically in my program. Probobly the best way would be to add macro to my file.

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Programming :: Python: Dynamically Create A List Within A Dictionary?

Jul 9, 2011

how to dynamically create a list within a dictionary using Python.

dates = defaultdict(int)
array = []
dates[] = array.append(date)
dates[] = [array.append(date)]

None of the above works and I've tried everything I can think of.

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Programming :: Wrote A Driver That Scans On Startup Dynamically For Available EEPROM's On A Certain IC Bus?

Jul 28, 2011

I wrote a driver that scans on startup dynamically for available EEPROM's on a certain IC bus. For each EEPROM a new character device is created in /dev like:

/dev/bus0eepromA2 ...


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Programming :: Unable To Dynamically Create An Array Of Params For Execv In C

Jan 6, 2011

I haven't programmed in C for a while, so I am trying to remember certain aspects of syntax. I have a program that will fork and exec other programs. Those programs will be specified on the command line as follows:

./main "prog1 arg arg ..." "prog2 arg arg ..."

Here is the main snippet:

int countChar(char* s, char c)
{ int cnt = 0;
int len = strlen(s);
for(int i = 0; i < len; i++)


The highlighted line is the problem. I get this error:

dualstarter.cpp:58: error: initializer fails to determine size of 'params'.

Right now I am thinking of creating an array with the specified size and simply copying the required string into it, but it just seems like there is an easier way.

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Programming :: Read Any Given Maze.txt Into An Internal Dynamically Allocated Array Of Strings?

Apr 26, 2011

I am looking for an easy way to convert any given maze.txt of any size to a internal array of strings(dynamically allocated). Important is that dimensions of the maze (row, col) shouldn't be written by the user instead they have to be somehow read from the file. This is not my homework assignment! It is a small part of a project that i never dealt with. I never read files to C string.... I made it for specific maze dimensions, but want it to work with any given .txt file.

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Programming :: MYSQL Driver Is Not Loaded

Dec 25, 2010

I also the same problem, just that I can not proceed in the same way because I use Ubunto, what should I do to install the MySQL driver on my PC?

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Programming :: Jquery To Dynamically Create Cookies Using The Jquery Cookie Plugin?

Jul 27, 2011

I am learning jquery and I think for the most part I have the basics down. One of the things that I am attempting to do is to create cookies using the jquery cookie plugin. The idea is that I want to replace as much of the javascript in my code as possible with jquery to see the difficulties in doing it one way or the other.

As easy as it seems to be able to create a cookie using the plugin I have not been able to do some successfully and the only thing that I can think of is the way that I am submitting my parameters is not correct. So with that, here is is my code:


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Programming :: After USB Boot - Detect Which Device The Ramfs Was Loaded From - Bash Or Python

Sep 22, 2010

How one could determine (for use in a Bash or Python script) which device (eg /dev/sda1, /dev/hda1... etc) a ramfs was loaded from when booting from a USB drive.

I have a RIPLinux/Tinycore live USB disk that automatically needs to run a script that is stored on the same USB drive but not part of the RIPLinux/Tinycore image. (Please note that I do not want to put this script into the RIPLinux image.) I therefore would like to remix the RIPLinux/Tinycore ISO to automatically run this script once it has started up. After RIP linux has booted I would like to automatically mount the USB drive that RIPLinux/Tinycore was booted from. I need help detecting which device this is.

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Programming :: Groovy Scripting - An Object-oriented Programming Language For The Java Platform ?

Mar 7, 2010

Groovy is an object-oriented programming language for the Java platform. I do not have experience in Java, only perl and shell scripts. Recently I have been asked to maintain a software written in groovy (also to make enhancements). So can I learn groovy without knowing java language. or isit I have to learn java before venturing into groovy.

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General :: How To Connect Two Different Ip Classes In Lan In System

Jun 14, 2010

In our LAN connection setup. having and how do i connected intermediately. server are RHEL5.

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Ubuntu :: Send .docx For College Classes?

Apr 2, 2011

I started taking CIT 101 (computer classes 101 LOL i know) as I am strict linux, in my house, purchasing office 2007 yes they require 2007 not 2010. Columbus State is tough on that, I need to be able to send documents in 2007 .docx in openoffice 3.3. The only computer that uses windows, is my grandparents and I don't want to buy Office if at all possible. I have like no money after all the text books. Teacher is strict it can not be .doc, odt. or other, needs to be .docx

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General :: Cups Implicit Classes And Windows

Oct 20, 2010

To foster from the failover concept of Cups I have set up 2 servers with the same printers and settings to enable the implicit classes.

Server A

I added first aprinter defined with the name myprinter (a Ricoh MP5000)

Server B

On Server B i did no printer definition

That is working fine on Cups web interface of Server B i see queuename Server A.myprinter(and vice versa).

Now I add the printer (without samba via ipp) to my windows client with the parameters [url]. I can print that way all ok. The job appears and will be printed on Server A

When I disable myprinter on A. I cannot print. I expected with the implicit classes that it switches to Server B. Is the idea wrong ? Or is Windows limited here ? Or is there another way of defintion I have to do.

My both servers are running on different platforms Suse SLES 10 and Red Hat. CUPS version 1.4.4

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Server :: Tomcat 7.0.8 Not Finding Packaged Classes?

Mar 11, 2011

I'm trying to set up Apache Tomcat with virtual hosting. I've used Caucho Resin before but not Tomcat...and I've run into what appears to be (from Google at least) a rather common problem with Tomcat in that any properly packaged classes under WEB-INF of the default virtual host or the named host are not found and Tomcat complains of a class that "cannot be resolved to a type". I researched this error on Google and the consensus seems to be that: -

- You need properly packaged classes as classes in the default package are no longer allowed. I have done this.

- You need to either fully declare the packaged class to make an instance of it within the JSP or include the via an import statement at the top of the JSP. I have done this.

- In the web.xml for the Tomcat server instance (under $CATALINA_HOME/conf/web.xml) you need to set the servlet mapping for JSPs fork init-param to "true". I have done this also.

Yet the problem persists and I have found no solution. So I can only assume I'm missing something obvious and fundamental. My configuration is as follows: - I have two virtual hosts - one as the default virtual host and another as a named virtual host.

$CATALINA_HOME/webapps/localhost <--- Default host.
$CATALINA_HOME/webapps/ <--- Named host. The logic being that the URL IP address of the server will hit the default webapp and the URL hostname with hit the named webapp. This appears to work with just JSPs.

My $CATALINA_HOME/conf/server.xml looks like this: -


<?xml version='1.0' encoding='utf-8'?>
<Server port="8005" shutdown="SHUTDOWN">
<Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
<Listener className="org.apache.catalina.core.JasperListener" />


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Programming :: Using XML In Java?

Jan 6, 2011

how to implement this.

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