Dynamic class calling

Hi All,
I want to know the same class name which I am executing in the constructor of the class. Is there any system variable which stores this information. Like for example sy-repid for reports.
Then after getting the calss name in string how I am going instantiate the same.
Regards,
Guru Dutt

Hi,
There is a standard interface A with methods A1(Instance dependent), A2(static). There is a custom class B which uses the interface A. There is a sub-class C which inherits B as super-class.
A(Interface)->B(Super Class)->C(Sub Class)
Now method A2 can be modified in class B. So here I can create a object refernce of type B. But when the same method A2 is visible in class C I cannot create obejct reference for class C. in method A2.
So for the same reason I needed to know the calling class name so that I can make the object reference dynamic based on calling class.
Please let me know is there any way to handle this.
Regards,
Guru

Similar Messages

How to create a dynamic class

Hiya,
I want to create classes dynamically. I know that this can be done by extending ClassLoader and defineClass method. My problem is i dont know what goes in byte[] coz my program needs to get the class name, attributes and methods from the user.
For example something like visual modeler that loads up the UI than lets the user to create the classes, attributes and methods.
The generic class called gentity is as follows:
public class Gentity {
private String gname;
public Gentity(String mgname) {
gname=mgname;
public void setGname(String mgname)
gname=mgname;
public String getGname()
{return(gname);
This class will then be used in my main class which is as follows:
public class GentityClassLoader extends ClassLoader
Gentity customer=new Gentity("HSBC");
public static void main(String argv[])
byte b[]=new byte[1];
GentityClassLoader obj = new GentityClassLoader();
try{
// this is my problem here, i dont know what goes in bytes
Class cls = obj.defineClass(obj.customer.getGname(),b,0,b.length);
Class x=obj.loadClass(obj.obj.getGname());
obj.resolveClass(x);
System.out.println(x.toString()+"asdf");
}catch(Exception e)
System.out.println("Error");
Cheers,
Deepak

You start by reading the JVM spec.
http://java.sun.com/docs/books/vmspec/html/VMSpecTOC.doc.html

Dynamic class loading problem using unknown JAR archive and directory names

I read the following article, which enlightened me a lot:
Ted Neward: Understanding Class.forName().
However, it took me some while to understand that my problem is the other way around:
I know the name of the class, I know the name of the method,
but my program/JVM does not know where to load the classes from.
Shortly, my problem is that the server engine that I am writing
uses two different versions of the same library.
So I am trying out the following solution:
My program is named TestClassPathMain.java
Assume the two libraries are named JAR1.jar and JAR2.jar
and the class/instance method that should
be exposed to TestClassPathMain.java by them is named
TestClass1.testMethod().
As long as I was depending on just one library,
I put JAR1.jar in the classpath before starting java,
and I was happy for a while.
At the moment I got the need to use another version of
TestClass1.testMethod() packaged in JAR2.jar,
a call would always access JAR1.jar's
TestClass1.testMethod().
I then decided to remove JAR1.jar from the classpath,
and programmatically define two separate ClassLoaders, one for use
with JAR1.jar and the other for use with JAR2.jar.
However, the problem is only partly solved.
Please refer to the enclosed code for details.
(The code in the JAR1.jar/JAR2.jar is extremely simple,
it just tells (by hardcoding) the name of the jar it is packaged in
and instantiates another class packaged in the same jar using
the "new" operator and calls a method on it. I don't enclose it.)
The TestClassPathMain.java/UC1.java/UC2.java code suite was
successfully compiled with an arbitrary of JAR1 or JAR2 in the classpath,
however removed from the classpath at runtime.
(I know that this could have been done (more elegantly...?) by producing an Interface,
but I think the main problem principle is still untouched by this potential lack of elegancy(?))
1) This problem should not be unknown to you experts out there,
how is it generally and/or most elegantly solved?
The "*** UC2: Variant 2" is the solution I would like best, had it only worked.
2) And why arent "*** UC2: Variant 2" and
"*** static UC2: Variant 2" working,
while "*** Main: Variant 2" is?
3) And a mal-apropos:
Why can't I catch the NoClassDefFoundError?
The output:
*** Main: Variant 1 JAR 1 ***:
Entering TestClass1.testMethod() packaged in JAR1.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR1.jar
*** Main: Variant 1 JAR 2 ***:
Entering TestClass1.testMethod() packaged in JAR2.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR2.jar
*** Main: Variant 2 JAR 1 ***:
Entering TestClass1.testMethod() packaged in JAR1.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR1.jar
*** Main: Variant 2 JAR 2 ***:
Entering TestClass1.testMethod() packaged in JAR2.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR2.jar
*** UC1: Variant 1 JAR 1 ***:
Entering TestClass1.testMethod() packaged in JAR1.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR1.jar
*** UC1: Variant 1 JAR 2 ***:
Entering TestClass1.testMethod() packaged in JAR2.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR2.jar
*** static UC2: Variant 2 JAR 1 ***:
Exception in thread "main" java.lang.NoClassDefFoundError: TestClass1
        at UC2.runFromJarVariant2_static(UC2.java:56)
        at TestClassPathMain.main(TestClassPathMain.java:52)
TestClassPathMain.java
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
public class TestClassPathMain {
    public static void main(final String args[]) throws MalformedURLException, ClassNotFoundException, InstantiationException, SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
            // Commented out because I cannot catch the NoClassDefFoundError.
            // Why?
            try {
                final TestClass1 testClass1 = new TestClass1();
                System.out.println(
                    "\nThe class TestClass1 is of some unexplicable reason available." +
                    "\nFor the purpose of the test, it shouldn't have been!" +
                    "\nExiting");
                System.exit(1);
            } catch (NoClassDefFoundError e) {
                System.out.println("\nPositively confirmed that the class TestClass1 is not available:\n" + e);
                System.out.println("\n\nREADY FOR THE TEST: ...");
            // Works fine
            System.out.println("\n*** Main: Variant 1 JAR 1 ***:");
            runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** Main: Variant 1 JAR 2 ***:");
            runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
            // Works fine
            System.out.println("\n*** Main: Variant 2 JAR 1 ***:");
            runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** Main: Variant 2 JAR 2 ***:");
            runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
            // Works fine
            final UC1 uc1 = new UC1();
            System.out.println("\n*** UC1: Variant 1 JAR 1 ***:");
            uc1.runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** UC1: Variant 1 JAR 2 ***:");
            uc1.runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
            // Crashes
            System.out.println("\n*** static UC2: Variant 2 JAR 1 ***:");
            UC2.runFromJarVariant2_static("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** static UC2: Variant 2 JAR 2 ***:");
            UC2.runFromJarVariant2_static("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
            // Crashes
            final UC2 uc2 = new UC2();
            System.out.println("\n*** UC2: Variant 2 JAR 1 ***:");
            uc2.runFromJarVariant2("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** UC2: Variant 2 JAR 2 ***:");
            uc2.runFromJarVariant2("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
    private static void runFromJarVariant1(final String jarFileURL)
        throws MalformedURLException,
               ClassNotFoundException,
               InstantiationException,
               IllegalArgumentException,
               IllegalAccessException,
               InvocationTargetException,
               SecurityException,
               NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final Object testClass1 = clazz.newInstance();
        final Method testMethod1 = clazz.getMethod("testMethod", null);
        testMethod1.invoke(testClass1, null);
    private static void runFromJarVariant2(final String jarFileURL)
        throws MalformedURLException,
               ClassNotFoundException,
               InstantiationException,
               IllegalArgumentException,
               IllegalAccessException,
               InvocationTargetException,
               SecurityException,
               NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final TestClass1 testClass1 = new TestClass1();
        testClass1.testMethod();
UC1.java
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
public class UC1 {
    public void runFromJarVariant1(final String jarFileURL)
        throws MalformedURLException,
               ClassNotFoundException,
               InstantiationException,
               IllegalArgumentException,
               IllegalAccessException,
               InvocationTargetException,
               SecurityException,
               NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final Object testClass1 = clazz.newInstance();
        final Method testMethod1 = clazz.getMethod("testMethod", null);
        testMethod1.invoke(testClass1, null);
UC2.java
import java.lang.reflect.InvocationTargetException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
public class UC2 {
    public void runFromJarVariant2(final String jarFileURL)
    throws MalformedURLException,
           ClassNotFoundException,
           InstantiationException,
           IllegalArgumentException,
           IllegalAccessException,
           InvocationTargetException,
           SecurityException,
           NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final TestClass1 testClass1 = new TestClass1();
        testClass1.testMethod();
     * Identic to the "runFromJarVariant2" method,
     * except that it is static
    public static void runFromJarVariant2_static(final String jarFileURL)
    throws MalformedURLException,
           ClassNotFoundException,
           InstantiationException,
           IllegalArgumentException,
           IllegalAccessException,
           InvocationTargetException,
           SecurityException,
           NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final TestClass1 testClass1 = new TestClass1();
        testClass1.testMethod();
}

2. i need to load the class to the same JVM (i.e. to
the same environment) of the current running
aplication, so that when the loaded class is run, it
would be able to invoke methods on it!!!
ClassLoader(s) do this. Try the URLClassLoader.
(I was talking about relatively esoteric "security"
issues when I mentioned the stuff about Class objects
"scope".) You might use the URLClassLoader kind of
like this.
Pseudo-code follows:
// setup the class loader
URL[] urls = new URL[1];
urls[0] = new URL("/path/to/dynamic/classes");
URLClassLoader ucl = new URLClassLoader(urls);
// load a class & use make an object with the default constructor
Object tmp = ucl.loadClass("dynamic.class.name").newInstance();
// Cast the object to a know interface so that you can use it.
// This may be used to further determine which interface to cast
// the class to. Or it may simply be the interface to which all
// dynamic classes have to conform in your program.
InterfaceImplementedByDynamicClass loadedObj =
    (InterfaceImplementedByDynamicClass)tmp;It's really not as hard as it sounds, just write a little test of
this and you will see how it works.

Dynamic class loading when CODEBASE is unreachable. A bug?

Let us suppose that we have a large-scale distributed application with ca. 1000 participants communicating via RMI and utilizing dynamic class loading. As we all know, a HTTP code server must be available for this purpose in order to provide dynamically downloaded code, usually the communication proxy code of remote objects. In a real-world scenario, the HTTP server will never be 100% available, so that we will have cases that a Java process will not be able to download the necessary Java classes, causing the RMI communication to fail with a ClassNotFoundException or similar exception. In such a case, a robust application would perform some recovery activities and retry the remote call. Eventually, the HTTP server becomes available again and the distributed system recovers automatically. This seems to work fine with J2SE 1.4.2_10, but not with 1.4.2_11 and newer versions. Considering Java 5, the Update 9 exhibits the same problem.
For tracking down the problem, I've written a simple distributed test application, consisting of a client and a server. A server listens on a port, and sends a MarshalledObject to the client. The code of the MarshalledObject is annotated with the value of the "java.rmi.server.codebase" system property. The annotation contains an URL of the JAR file containing the code of the original object. The client connects to the server, reads data form the socket and unmarshalls the original object. This is basically the same procedure as when objects are accross the wire as arguments/return values/exceptions by the RMI/JRMP engine. This procedure is repeated forever in the loop. Due to the fact that the client's CLASSPATH doesn't contain the code of the original object, this code should dynamically be loaded from the HTTP server using the appropriate annotation provided by the server.
If we start the client while the HTTP server is down, the client will keep generating the ClassNotFoundException over and over again, as expected. So far, so good. If we now start the HTTP server while the client is still running, we will observe different behaviors, depending on the version of the client's JVM:
1. In J2SE 1.4.2_10, the client will download the code from the HTTP server and successfully unmarshal the original object sent by the server. ClassNotFoundExceptions will not be generated again.
2. In J2SE 1.4.2_11, 1.4.2_12 and 1.4.2_13 as well as in J2SE 5.0 Update 9, the client will continue generating ClassNotFoundExceptions. Analysis of the HTTP server's access log shows that there were no attempts to download the JAR file required for unmarshaling the object sent by the server.
It seems that in the newer JVM versions the RMI engine remembers URLs which have failed and does not attempt to access them anymore. Althogh this may have some advantages considering the overall network load, the dynamical class loading becomes practically useless in productive large distributed systems. The very first attempt to load the codebase of the communication peer must succeed, otherwise the whole process must be restarted for the communication to work, which is a very expensive (and for most customers unacceptable) operation in terms of preformance and resources usage.
Should this be seen as a bug or a feature of the JVM? What do you think?
Regards,
Miran
Here is the code to reproduce:
Server code
package server;
import java.net.*;
import java.rmi.*;
import java.io.*;
public class Server implements Serializable {
private int value = 42;
public Server() {
public String toString() {
    return "The Answer is " + value;
public static void main( String[] args ) {
    if( args.length!=1 ) {
      System.out.println( "Usage: server.Server <port>" );
      System.exit( 1 );
    try {
      MarshalledObject data = new MarshalledObject( new Server() );
      int port = Integer.parseInt( args[0] );
      ServerSocket serverSocket = new ServerSocket( port );
      System.out.println( "Accepting connections..." );
      while( true ) {
        Socket s = serverSocket.accept();
        new Thread( new SocketHandler( s, data ) ).start();
    } catch( Exception ex ) {
      ex.printStackTrace();
    System.exit( 0 );
public static class SocketHandler implements Runnable {
    private Socket s;
    private Serializable data;
    public SocketHandler( Socket s, Serializable data ) {
      this.s = s;
      this.data = data;
    public void run() {
      try {
        OutputStream os = s.getOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream( os );
        oos.writeObject( data );
        oos.close();
        os.close();
        s.close();
        System.out.println( "Serving socket succeeded" );
      } catch( Exception ex ) {
        System.out.println( "Serving socket failed" );
        ex.printStackTrace();
Client code
package client;
import java.rmi.*;
import java.net.*;
import java.io.*;
public class Client {
public static void main( String[] args ) {
    if( args.length!=1 ) {
      System.out.println( "Usage: client.Client <port>" );
      System.exit( 1 );
    try {
      if( System.getSecurityManager()==null ) {
        System.setSecurityManager( new RMISecurityManager() );
      int port = Integer.parseInt( args[0] );
      for( int i = 1; true; ++i ) {
        try {
          Socket s = new Socket( "localhost", port );
          InputStream is = s.getInputStream();
          ObjectInputStream ois = new ObjectInputStream( is );
          Object o = ois.readObject();
          ois.close();
          is.close();
          s.close();
          Object umo = ((MarshalledObject) o).get();
          System.out.println( i + ". Retreiving MarshalledObject succeeded: "
                              + umo );
        } catch( Exception ex ) {
          System.out.println( i + ". Retreiving MarshalledObject failed" );
          ex.printStackTrace();
        System.out.println( i + ". Waiting for 10 sec" );
        Thread.sleep( 10000 );
    } catch( Exception ex ) {
      ex.printStackTrace();
    System.exit( 0 );
Start command for the server
java -cp server.jar -Djava.rmi.server.codebase="http://localhost/playground/server.jar" server.Server 33933
Start command for the client
java -cp client.jar -Djava.security.policy=all.policy client.Client 33933
The policy.all file should look as follows
// All permissions
grant {
   permission java.security.AllPermission;
};The server.jar file should only contain the classes from the server package. This file should also be made accessible via HTTP (e.g. by using the Apache HTTP server).
The client.jar file should only contain the classes from the client package.

no body know about this??

Dynamic class & property

Hi there!
I would like to know, if it is possible to mimic the behavior of XML dynamic class:
var xm:XML =
    <question idAttr="atribute xml">
    </question>;
trace(xm.attributes());
trace("Attributes: "+xm["attributes"]);
xm["attributes"] = {a:"atr1", b:"atr2"}; (in my dynamic class with attributes function, I get ReferenceError: Error #1037)
trace("Attributes: "+xm["attributes"]);
trace(xm.attributes());
So I can call:
     xm.attributes() method which gives me XML attributes
and use
     xm["attributes"] = {a:"atr1", b:"atr2"};
which writes to the "attributes" property and not references the XML class function.
My question:
How can I do the same in my custom dynamic class ?
Gregory

As you might noticed some syntaxes of XML class' properties and methods are not conventional to AS3. This, perhaps, hints to the fact that XML class is not an AS3 class in its purest sense. In other words it is probably written in a different language (C? C++?...).
In AS3, unlike in other languages, you cannot name property and method the same. So, there is no way to have both "attributes" property and "attributes()" method.
Nevertheless, if you want to emulate XML functionality to some extend and enumerate/return dynamically set properties, you can definitely do that. This is an excellent case for using accessors (setters and getters):
package
     public dynamic class DynamicClass
          public function DynamicClass()
          public function get attributes():Object {
               var obj:Object = { };
               for (var prop:String in this) {
                    obj[prop] = this[prop];
               return obj;
          public function set attributes(obj:Object):void {
               for (var prop:String in obj) {
                    this[prop] = obj[prop];
Usage:
var dc:DynamicClass = new DynamicClass();
dc.prop2 = "BLAH";
dc.attributes = { propA: "bbb", anotherProp: 456 };
trace(dc["attributes"]);
for (var prop:String in dc.attributes) {
     trace(prop, "=", dc.attributes[prop]);
Message was edited by: Andrei1

Dynamic Class Loading with interface

Hello
I would appreciate any help on the following problem.
I need to load all classes in a particular directory and its subdirectories (top directory is known but not in the classpath) which implement a predefined interface. At the moment I am using a lot of reflection to accomplish this and believe it can be avoided somehow using the fact that I know these classes have to implement a predefined interface.
At the moment, I am searching through the directory and subdirectory, loading all names of classes into a vector using a custom URLClassloader, and then load all classes in the vector into modulecontainers to populate a defaultmutabletree which is displayed on the gui.
I'm sure that knowing the interface means there's a more straightforward way.
Thanks in advance.

Finally i've found out myself, i've read some postings in this forum and put them all together, so that my webstart-application finally works the way i want...
That was the topic:
Downloading a jar-file and starting a class from this jar-file within a webstart application (dynamic class loading).
I'll post my final solution for this problem, may be it would be useful in future for anyone else.
//grant all permissions on the clientside
Policy.setPolicy( new Policy() {
public PermissionCollection getPermissions(CodeSource codesource) {
Permissions perms = new Permissions();
perms.add(new AllPermission());
return(perms);
public void refresh(){
//get the current classloader
ClassLoader cl = MyLoadedClass.class.getClassLoader();
//create a new url-classloader while using the current classloader
URL[] urls = new URL[1];
File f = new File(new String(jarName));
urls[0] = f.toURL();
URLClassLoader ul = new URLClassLoader(urls, cl);
//load a class from jarfile
Class c = ul.loadClass(new String(className));
//get an object from loaded class
Object o = c.newInstance();
/* Are we using a class we specifically know about? */
if (o instanceof KnownInterface){
// Yep, lets call a method we know about. */
KnownInterface client = (KnownInterface) o;
client.doAnything();

Dynamic class loading with Webstart

Hello !
//within the jar-file at the webstart-directory
public interface MyFrame{
public void createFrame();
//within the jar-file dynamically downloaded
public class MyExtFrame extends JFrame implements MyFrame{
String className = "MyExtFrame";
ClassLoader cl = ClassLoader.getSystemClassLoader();
JarClassLoader jarLoader = new JarClassLoader (cl, jarFile));
/* Load the class from the jar file and resolve it. */
Class c = jarLoader.loadClass (className, true);
/* Create an instance of the class.
Object o = c.newInstance();
/* Are we using a class we specifically know about? */
if (o instanceof MyFrame){
// Yep, lets call a method we know about. */
MyFrame client=(MyFrame) o;
//call a class-method (here creates the whole gui-object at once)
client.createFrame();
This is the code i'm using and i've encountered following problem, if i put this code into an application without webstart, anything works fine, but with webstart i'll get a: java.lang.NoClassDefFoundError
Then i've put the MyFrame-classes into the downloaded jar-file, but this won't work either, i'll get a ClassCastException.
What do i have to do, to become it working ?
Thanks for any conclusions and help.
Michael

Finally i've found out myself, i've read some postings in this forum and put them all together, so that my webstart-application finally works the way i want...
That was the topic:
Downloading a jar-file and starting a class from this jar-file within a webstart application (dynamic class loading).
I'll post my final solution for this problem, may be it would be useful in future for anyone else.
//grant all permissions on the clientside
Policy.setPolicy( new Policy() {
public PermissionCollection getPermissions(CodeSource codesource) {
Permissions perms = new Permissions();
perms.add(new AllPermission());
return(perms);
public void refresh(){
//get the current classloader
ClassLoader cl = MyLoadedClass.class.getClassLoader();
//create a new url-classloader while using the current classloader
URL[] urls = new URL[1];
File f = new File(new String(jarName));
urls[0] = f.toURL();
URLClassLoader ul = new URLClassLoader(urls, cl);
//load a class from jarfile
Class c = ul.loadClass(new String(className));
//get an object from loaded class
Object o = c.newInstance();
/* Are we using a class we specifically know about? */
if (o instanceof KnownInterface){
// Yep, lets call a method we know about. */
KnownInterface client = (KnownInterface) o;
client.doAnything();

Is it possible to remove properties from a dynamic class?

I have a dynamic ActionScript Class that is used to send
parameters to a WebService. Some of these parameters are always
present, so they are public properties of the Class:
package
[Bindable]
public dynamic class WebServiceCriteria
public var property1:int;
public var property2:String;
public var property3:String;
public var property4:String;
But, I am also adding properties at runtime that can change
over time:
criteria.runTimeProperty = "1";
I'm not very familiar with using dynamic classes, so I was
wondering if it is possible to "remove" the new property. Let's say
the next time I call the WebService I don't want that property sent
- not even as a null. How can I remove it from the Class instance
without creating a new instance each time?

Hi,
Please try delete criteria.runTimeProperty. Please find more
details on the delete operator at the URL below.
http://livedocs.adobe.com/flex/3/langref/operators.html#delete
Hope this helps.

Dynamic method calls in bounded task flows?

Hi!
I have the following scenario:
We are developing a framework in which we would include modules as ADF libraries (as JAR files) with bounded task flows. This framework contains a bean class with bindings for some UI components in framework which I enable or disable (depends on user action). That is the main reason bean class should be present in framework application.
I have a bounded task flow in every module which needs to call a method in bean with UI component's bindings that would enable or disable that component.
How can I achieve that? To pass bean as a parameter into bounded task flow and then call its methods? That is dynamic method calls for bean.
I'm using JDeveloper 11.1.2.1.0
Thanks for your help
Regards, Marko

Hi,
I explained this; +"I have a bounded task flow in every module which needs to call a method in bean with UI component's bindings that would enable or disable that component. How can I achieve that? To pass bean as a parameter into bounded task flow and then call its methods?"+ a couple of times already (not sure if it was all for you) and don't think I change my position here. I also explained how to use a ValueExpression to lookp a managed bean containing component bindings (should be in requestscope).
Frank

Dynamic Class Loading (RMI)

Hi,
i have my rmi server, implementing objects,stubs and skeleton classes deployed in my Tomcat server and they are stored under the tomcat root folder.
In anoather jvm iam trying to load the classes thru the below code.
java -Djava.rmi.server.codebase=http://ssd8/tomcat-3.2.4/install_dir/webapps/ROOT/WEB-INF/rmicode stockMarketClient
ssd8 is the hostname(machine) which contains all my rmi server files.
and stockmarketclient is my rmi client.
Iam getting the java.lang.noclassdeffound error.
what may be the problem???
Should i have the security policy file in the client machine.

Please Do tell me if any of the following worked I'll be greatly obliged
1) Try this
java -Djava.rmi.server.codebase=http://servername/dir1/dir2/ RMIServer
This / thing at the end of the URL is very important
2) This is how I did it just Today
Dynamic Class Loading Using RMI
     Server Side
1) Main Interface
2) Implementing Class
3) Stub & Skel                    (RMI Server & Web Server)
4) All Other Classes used by the Server
     Web Server Side
1) Main Interface
2) Stub & Skel                    (RMI Server & Web Server)
3) All Other Classes (not Main Client Class)
     Client Side
1) Main Interface
2) Main Client Class
3) Stubs
4) Security Manager
     RUNNING
SERVER
     java DataServerImpl
CLIENT
     java DataClient xyz
Note
Make Calls as follows
System.setSecurityManager(new LaxSecurityManager());
DataServer server = (DataServer) Naming.lookup("rmi://localhost:1099/DataServer");
Runnable r = (Runnable)server.getNewClass();
r.run();
DON'T make Calls as follows
System.setSecurityManager(new LaxSecurityManager());
DataServer server = (DataServer) Naming.lookup("rmi://localhost:1099/DataServer");
NewClass obj = server.getNewClass();
obj.run();
if done as above provide the Class NewClass to the Client as well ( whole purpose defeated)
Code
     // SecurityManager
import java.rmi.*;
import java.security.*;
public class LaxSecurityManager extends RMISecurityManager
     // All Checks are routed through this method
     public void checkPermission(Permission p)
          // do nothing
     // Main Interface
import java.rmi.*;
public interface DataServer extends Remote
     public boolean login(String usr_name,char[] pass_wrd) throws RemoteException;
     public Object getNewClass() throws RemoteException;
     // Main Server
import java.rmi.*;
import java.rmi.server.*;
import java.rmi.registry.*;
public class DataServerImpl /*extends UnicastRemoteObject*/ implements DataServer
     static
          try
               LocateRegistry.createRegistry(1099);
          catch(Exception e)
               System.err.println("Static " + e);
     public boolean login(String usr_name,char[] pass_wd) throws RemoteException
          System.out.println("Welcome " + usr_name);
          if( pass_wd == null || pass_wd.length == 0 || pass_wd.length > 10 )
               return false;
          return true;
     public Object getNewClass() throws RemoteException
          System.out.println("Returning New Class");
          return new NewClass();
     public DataServerImpl() throws RemoteException
          try
               System.setProperty("java.rmi.server.codebase","http://localhost:8080/");
               UnicastRemoteObject.exportObject(this);
               Naming.rebind("DataServer",this);
          catch(java.net.MalformedURLException e)
               System.err.println("DataServerImpl " + e);
               return;
          System.out.println("Server Registered");
     public static void main(String[] args) throws Exception
          new DataServerImpl();
     // Class Moving Around the Network
public class NewClass implements java.io.Serializable,Runnable
     int num;
     public void run()
          System.out.println("Start the Server with Number = " + num);
     public NewClass()
          num = (int)(Math.random()*1000);
     public String toString()
          return num + "";
     // Client
import java.rmi.*;
public class DataClient
     public static void main(String[] args) throws Exception
          System.setSecurityManager(new LaxSecurityManager());
          String pass = new String();
          if(args.length == 0)
               System.err.println("usage: java DataClient PassWord");
               System.exit(1);
          else
               pass = args[0];
          DataServer server = (DataServer) Naming.lookup("rmi://localhost:1099/DataServer");
          Runnable r = (Runnable)server.getNewClass();
          r.run();
All the Best

Type conflict during dynamic method call.

While executing the following program I get the error "Type conflict during dynamic method call.":
DATA: container_r TYPE REF TO object,
      grid_r       TYPE REF TO object,
      itab_saplane TYPE TABLE OF saplane.
* IMPORTANT NOTE: class names must be in UPPER CASE
DATA: str_cnt TYPE seoclsname VALUE 'CL_GUI_CUSTOM_CONTAINER',
      str_gui TYPE seoclsname VALUE 'CL_GUI_ALV_GRID',
      meth_name TYPE STRING VALUE 'SET_TABLE_FOR_FIRST_DISPLAY'.
TYPE-POOLS abap.
DATA: ptab    TYPE abap_parmbind_tab,
      wa_ptab LIKE LINE OF ptab,
      ref     TYPE REF TO data.
CREATE OBJECT container_r TYPE (str_cnt)
EXPORTING container_name = 'CUSTOM_CONTROL1'. " Name of the custom control area (UC!)
* Construct parameter itab
GET REFERENCE OF container_r INTO ref.
wa_ptab-name = 'I_PARENT'. " Must be upper-case
wa_ptab-value = ref.
INSERT wa_ptab INTO TABLE ptab.
*   EXPORTING i_parent = container_r.
CREATE OBJECT grid_r TYPE (str_gui)
PARAMETER-TABLE ptab.
SELECT * FROM saplane INTO CORRESPONDING FIELDS OF TABLE itab_saplane.
* Cannot call set_table_for_first_display directly...
CALL METHOD grid_r->(meth_name)
EXPORTING I_STRUCTURE_NAME = 'SAPLANE' " Type of the rows in the internal table (UC!)
CHANGING IT_OUTTAB = itab_saplane.     " The internal table itself
CALL SCREEN 100.
Any help would be appreciated!

Hi ...
Apologies ... for confusion ... actually both are required ...
the type 'E' as well as CL_GUI_CONTAINER.
The below code worked for me ...
check out how I cast it to the parent class type ...
DATA : lv_container   TYPE seoclsname VALUE 'CL_GUI_CUSTOM_CONTAINER',
         lv_control     TYPE seoclsname VALUE 'CL_GUI_ALV_GRID',
         lv_method      TYPE string VALUE 'SET_TABLE_FOR_FIRST_DISPLAY',
         lt_par_tab     TYPE abap_parmbind_tab,
         ls_param       LIKE LINE OF lt_par_tab,
         lref_cont      TYPE REF TO cl_gui_container,
         lv_data        TYPE REF TO data.
CREATE OBJECT lref_container
      TYPE
        (lv_container)
      EXPORTING
        container_name = 'ALV_AREA'.
    ls_param-name = 'I_PARENT'.
    ls_param-kind = 'E'.
    lref_cont ?= lref_container.
    GET REFERENCE OF lref_cont INTO lv_data.
    ls_param-value = lv_data.
    INSERT ls_param INTO TABLE lt_par_tab.
** Now create ALV Control.
    CREATE OBJECT lref_alv_ctrl
      TYPE
        (lv_control)
      PARAMETER-TABLE
        lt_par_tab.
** Set table for 1st display
    DATA : lv.
    lv = lref_alv_ctrl->mc_fc_print.
    CALL METHOD lref_alv_ctrl->(lv_method)
      EXPORTING
        i_structure_name = 'T001'
      CHANGING
        it_outtab        = lt_company.
Cheers
Edited by: Varun Verma on Aug 12, 2008 4:19 PM

Help with loading dynamic classes ..need help please

i'm trying to design a program where by i can load dynamic classes
the problem i'm getting is that only one class is loading.
classes are loaded by their names,and index numbers of public methods from a linklist
.When the program runs only the first class is ever loaded and only the methods of that class ..
help please
//class loader
import java.lang.reflect.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
public class Test2 extends Thread
     public Class c;
     public Class Ray;
     public Class[] x;
     public static Object object = null;
     public Method[] theMethods;
     public static Method[] method,usemethod;
     public int methodcount;
     public static int MethodCt;
     public static JList list;
public Method[] startClass(String SetMethodName)
     try
          c = Class.forName(SetMethodName);
          object = c.newInstance();
          theMethods = c.getDeclaredMethods();
          // number of methods
          //methodcount = theMethods.length;
     catch (Exception e)
          e.printStackTrace();
// return the array then invoke the particular method later
return theMethods ;
public void RunMethod(Method[] SomeMethod, int methodcount)
     try
          SomeMethod[methodcount].invoke( object,null );
     catch (Exception e)
          e.printStackTrace();
// end class loader
//main calling program
import java.awt.*;
import java.awt.event.*;
import javax.swing .*;
import java.lang.reflect.*;
public class JFMenu extends JFrame
     public static JMenu pluginMenu;
     public static JMenuBar bar;
     public static final Test2 w = new Test2();
public static Method[] setmethod;
private static ClassLinkList startRef = null;
private static ClassLinkList linkRef3 = null;
private static ClassLinkList startRef2 = null;
private String ClassName,ShortCut;
private int MethodNumber;
private JMenuItem PluginItem;
     JFMenu()
          super (" JFluro ");
          JMenu fileMenu = new JMenu("File");
          fileMenu.setMnemonic('F');
          JMenuItem exitItem = new JMenuItem("Exit");
          exitItem.setMnemonic('X');
          fileMenu.add(exitItem);
          exitItem.addActionListener
               new ActionListener()
                    public void actionPerformed(ActionEvent event )
                         System.exit(0);
          JMenu pluginMenu = new JMenu("Plugins");
          pluginMenu.setMnemonic('P');
          startRef = new ClassLinkList ("Hello","Hello ",2,1926,"Painter");
          addToList("Foo","Foo ",0,1930,"Author");
          while (startRef.linkRef5 != null)
               //pluginMenu.addSeparator();
               ClassName = startRef.linkRef5.className;
               ShortCut = startRef.linkRef5.shortcutName;
MethodNumber = startRef.linkRef5.methodNumber;
AddMenuItem(pluginMenu,ShortCut,ClassName,MethodNumber);
               startRef.linkRef5 = startRef.linkRef5.next;
          // create menu bar and add JFMenu window to it
          JMenuBar bar = new JMenuBar();
          setJMenuBar(bar);
          bar.add(fileMenu);
          bar.add(pluginMenu);
          //attributes for JFMenu frame
          setSize(500,200);
          setVisible(true);
     }// end JFMenu constructor
     public void AddMenuItem(JMenu MainMenu, String shortcut,String className, final int methodCount )
          if (MainMenu==null)
               return;
          //JMenuItem item;
          JMenuItem item = new JMenuItem(shortcut);
          MainMenu.add(item);
          setmethod = w.startClass(className);
          item.addActionListener
               new ActionListener()
                    public void actionPerformed(ActionEvent event )
                         w.RunMethod(setmethod,methodCount);
          //item.addActionListener(ij);
     public JMenuItem AddMenuItem2(JMenu MainMenu, String shortcut)
          //if (MainMenu==null)
          //     return Main;
          //JMenuItem item;
          JMenuItem item = new JMenuItem(shortcut);
          MainMenu.add(item);
          //setmethod = w.startClass(className);
          //item.addActionListener(this);
               new ActionListener()
                    public void actionPerformed(ActionEvent event )
                         w.RunMethod(setmethod,methodCount);
          //item.addActionListener(ij);
     return item;
     public void ReloadMenu(JMenuBar Bar, JMenu PluginMenu)
          if (Bar==null)
               return;
          //     setJMenuBar(Bar);
          Bar.add(PluginMenu);
          //item.addActionListener(ij);
public static void main (String args[])
          JFMenu menapp = new JFMenu();
public static void addToList(String clname, String shcutname, int metnumber, int year2,
                              String description) {
     // Create instance of class ClassLinkList
ClassLinkList newRef = new ClassLinkList(clname,shcutname,metnumber,year2,
                                   description);
// Add to linked list;
     startRef = startRef.addRecordToLinkedList(newRef);
// end main calling program
class Hello extends Thread
public int getNum()
System.out.println("I can be ");
return 5;
public void rayshowName()
System.out.println("anything i want ");
public void rayshowName3()
System.out.println("to be ");
class Foo extends Thread
public int getNum()
System.out.println("IMHOFF");
return 5;
public void rayshowName()
System.out.println("raYMOND");
// FAMOUS PERSONS LINKED LIST EXAMPLE
// Frans Coenen
// Saturday 15 January 2000
// Depaertment of Computer Science, University of Liverpool
class ClassLinkList {
/* FIELDS */
public String className;
public String shortcutName;
public int methodNumber;
public int yearOfDeath;
public String occupation;
public ClassLinkList next = null;
public ClassLinkList linkRef5 = this;
public ClassLinkList startRef = null;
/* CONSTRUCTORS */
/* FamousPerson constructor */
public ClassLinkList(String classname, String shortcutname, int methodnumber, int year2,
                              String description) {
     className = classname;
     shortcutName = shortcutname;
     methodNumber = methodnumber;
     yearOfDeath = year2;
     occupation = description;
     next = null;
/* METHODS */
/* Output famous person linked list */
public void outputClassLinkedList()
     //public ClassLinkList outputClassLinkedList() {
     ClassLinkList linkRef = this;
     // Loop through linked list till end outputting each record in turn
while (linkRef != null)
     //System.out.println(linkRef5);
     System.out.println(linkRef.className + ", " + linkRef.shortcutName +
               " (" + linkRef.methodNumber + "-" + linkRef.methodNumber +
               "): " + linkRef.occupation);
     linkRef = linkRef.next;
//return linkRef;
//public String ShowCasname()
//return String ;
/* Add a new record to the linked list */
public ClassLinkList addRecordToLinkedList(ClassLinkList newRef) {
     ClassLinkList tempRef, linkRef;
     // Test if new person is to be added to start of list if so return
if (newRef.testRecord(this) ) {
     newRef.next = this;
     return(newRef);
     // Loop through remainder of linked list
     tempRef = this;
     linkRef = this.next;
     while (linkRef != null) {
     if (newRef.testRecord(linkRef)) {
     tempRef.next = newRef;
          newRef.next = linkRef;
          return(this);
     tempRef = linkRef;
     linkRef = linkRef.next;
// Add to end
tempRef.next = newRef;
     return(this);
/* Delete a record from the linked list given the first and last name. Four
posibilities:
1) Record to be deleted is at front of list
2) Record to be deleted is at end of list
3) Record to be deleted is in middle of list
4) Record not found. */
public ClassLinkList deleteRecord(String lName, String fName) {
ClassLinkList tempRef, linkRef;
// Record at start of list
if ((this.className == lName) & (this.shortcutName == fName))
     return(this.next);
     // Loop through linked list to discover if record is in middle of list.
     tempRef = this;
linkRef = this.next;
while (linkRef != null) {
     if ((linkRef.className == lName) & (linkRef.shortcutName == fName)) {
tempRef.next = linkRef.next;
return(this);
tempRef = linkRef;
linkRef = linkRef.next;
// Record at end of list, or not found
if ((linkRef.className == lName) & (linkRef.shortcutName == fName))
                    linkRef = null;
     else System.out.println("Record: " + lName + " " + fName + " not found!");
     return(this);
/* TEST METHODS */
/* Test whether new record comes before existing record or not. If so return
true, false otherwise. */
private boolean testRecord(ClassLinkList existingRef) {
     int testResult = className.compareTo(existingRef.className);
     if (testResult < 0) return(true);
     else {
     if ((testResult == 0) & (shortcutName.compareTo(existingRef.shortcutName) < 0 ))
                         return(true);
     // Return false
     return(false);
     public void addToList(String clname, String shcutname, int metnumber, int year2,
                              String description)
     // Create instance of class Famous Person
ClassLinkList newRef = new ClassLinkList(clname,shcutname,metnumber,year2,
                                   description);
// Add to linked list;
     startRef = startRef.addRecordToLinkedList(newRef);

I have a similar problem. I am writing a program to read the class names from database and instantiate several classes which extends from ServiceThread (an abstract class extending from Thread).
rs = pStmt.executeQuery();
while(rs.next()) {
String threadclassname = rs.getString("classname").trim();
try{
ServiceThread threadinstance = (ServiceThread)Class.forName(threadclassname).newInstance();
}catch ...
So far, only the first class is ever instantiated and runs fine. But subsequent classes do not even get pass the "... ... Class.forName(...).newInstance();" line.
Funny thing is that there are also no exceptions. The JVM just seem to hang there.

Static verse dynamic dispatch call

I'm just getting started with creating my own lab view classes using the class object but I'm having trouble with some of the basic concepts. Are there any good tutorials or knowledge base articles which talk about how to create and use LabVIEW classes? I'm getting hung on static verses dynamic dispatch calls specifically.
Any help would be appreciated!
Thank you,
Craig

I'm still getting a handle on LVOOP myself.
Those two different methods control which VI actually gets called when your app is running.
THe static method is very similar to calling a normal sub-VI in LV except you are passing LVOOP data.
The dynamic comes into play when you have more than one class and one is a child of the other. In that case you can create a VI for the child that has the same name as a VI in the parent, but because it has different data, the data it accepts and return is different. This OTHER VI in the child will under the right condition be called instead of the VI in the parent. I understand this to be concidered over-riding. Which versino will be called? It is dicated by the data you pass to the sub_VI call. If you pass the parent data, the parent versino will be called and vise versa.
So the VI to call is determined at run-time depending on the data.
I hope I got that right!
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

How to populate CONTROLLER in proxy class call?

Hi All
While calling proxy class, i want to populate input variable CONTROLLER. I want to use the method GET_MESSAGE_ID to get the message guid.
CONTROLLER is TYPE REF TO IF_AI_POSTING_CONTROLLER.
How can i get this populated thru my proxy class call?
Sample code is highly appreciated.
Thanks
Chandra

Can you let me know little bit more details. Is this server proxy? If yes, you can use the proxy access class CL_PROXY_ACCESS to access the runtime variables of the proxy. Check http://help.sap.com/saphelp_nw70ehp1/helpdata/en/51/d5cd16235e4643ae8ec92395c4ad97/frameset.htm
Controller is used for controlling the attributes of the message, say for example controlling initial values for fields etc.
Let me know if you need more info.
KK

GET SET function in a dynamic Class?

Is it possible to add a GET SET function in a dynamic class, like we can add properties to a dynamic class?

correction :
MyObjectProxy extends ObjectProxy{
override callProperty(
// your dyna logic
and expose new MyObjectProxy(dynaInstance)

Dynamic class calling

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