JUTableSortModel class model problem?

Hi, I somtimes get empty lines and other anomaly when scrolling down in a JTable, after rows sorting performance. I fix this problems in the my UI model. I increase Iterator's RangeSize, but this is not good idea.
I using Oracle jDeveloper Version 10.1.2.0.0 .
Anybody heard of this before?
Regards
Desislav

Hi Frank,
sorry but I havn't HR schema, otherwise I reproducable this testcase.
Desislav

Similar Messages

Eight-Class Model QoS for voice and video

One of the QoS recomendation in the SRND "Enterprise QoS" is to create a Eight-Class QoS Model utilizing a seperate priority queue for voice and video.
It says that even though you have only one physical priority queue, that LLQ has an implicit policer that allows for time-division multiplexing of the single priority queue. This implicit policer abstract the fact that there is essentially a single LLQ within the algorithm and, thus, allows for the "provisioning" of multiple LLQs.
My question is if anyone has tried this and if there are any limitations on the platforms that can support this "dual-LLQ design."

Design guide which is basically the QoSDesign recommendation bible.
http://www.cisco.com/univercd/cc/td/doc/solution/esm/qossrnd.pdf
It has a large section for WAN recommendations...while you may not
need to follow one of these Based on my understanding what what you
have for a link (DS3) and what you are trying to accomplish, I
believe the following section would be a good place to start.
- WAN Aggregator QoS Design
- WAN Edge Classification and Provisioning Models
- High Link Speed QoS Class Model
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Five Class Model QoS Design?

Hi all,
I work for a company with a medium-sized network. There are about seven MPLS WAN sites. One of them is a data-center. The rest are sites with mostly users. The sites are dispersed through-out the continental United States.
Currently, the network is a basic data IP network with no QoS. There are a few projects slated for 2010. One involves implementing VoIP between just two sites. The other project calls for implementing IP-Video-Conferencing between the majority of the sites.
Should I start out with just a five-class model?
        - voice
        - call-signalling
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        - default-traffic (all data)
Is there really need to break down the data traffic into QoS classes as well?
As always, thanks an advance for your help.
-Mike

msrohman wrote:Hi all,I work for a company with a medium-sized network. There are about seven MPLS WAN sites. One of them is a data-center. The rest are sites with mostly users. The sites are dispersed through-out the continental United States.Currently, the network is a basic data IP network with no QoS. There are a few projects slated for 2010. One involves implementing VoIP between just two sites. The other project calls for implementing IP-Video-Conferencing between the majority of the sites.Should I start out with just a five-class model?        - voice        - call-signalling        - IP video-conferencing        - streaming video        - default-traffic (all data)Is there really need to break down the data traffic into QoS classes as well?As always, thanks an advance for your help.-Mike
Mike
The answer is - it depends
Cisco recommend using the full model even if you don't actually use them or allocate bandwidth to them. That way you then don't have to go back and change all your configs if you need to add another class.
Weigh this against where you intend to use QOS primarily ie. on the WAN or LAN or both. The key thing is to talk to your WAN provider to understand what classes they provide ie. how many, how much each class costs etc. If they only provide 5 classes for example you could in theory simply use 5 classes internally and map these to the provider classes.
However there is nothing to stop you using 11 classes internally within your LAN and then mapping multiple internal classes to a single provider WAN class.
The other thing to bear in mind is the applications that make up the company data. Are there a few recognisable critical apps to the business of the company compared to the majority which are not critical. If so it may be worth reserving a class for these apps, even if you don't use it at the moment. If the time comes that the company then needs better performance for these apps you have already provisoned for it (makes you look good !), and you can simply map it to either a new provider class or an existing provider class with increased bandwidth.
It is basically a trade off between complexity of QOS configs and making things easier in the future and a lot depends on the apps that the company runs.
Jon

RMI class file problem

I have already write a RMI example for self-study successfully, but there are a little class file problem that I'm not able fix it.
In my RMI example there are 3 .java files (RMIServer.java, RMIClient.java and a MethodImpl.java)
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In order to run the RMI in a local envirnment, I divide them into 2 folders as listed below:
Server - RMIServer_Skel.class, RMIServer_Stub.class and the MethodImpl.class
Client - RMIServer_Stub.class, RMIClient.class and the MethodImpl.class
Then when I start to run them in a DOC envirnment...
start rmiregistry........(run successful and another rmiregistry DOC window created)
java RMIServer.........Exception in thread "main" java.lang.NoClassDefFoundError: RMIServer
Oops? Class not found? How can that be? And after that, I tried something.......to add the RMIServer.class into the Server folder.
Again, I start to run them in a DOC envirnment...
start rmiregistry........(run successful and another rmiregistry DOC window created)
java RMIServer.........The server is instantiated(run successful and print out a String)
Um...is the RMI have to run with a RMIServer.class file? But the RMI notes I refered from is not seems to be telling me to do this, are there any one can give me a helping hand?

please, go here, read thoroughly
http://java.sun.com/docs/books/tutorial/getStarted/cupojava/index.html

Generate Data model from Class model

I am using JDeveloper uml features for a first time, so I am interested if there is a option that I can generate class model to the data model.
If I have class model and than when right-click select Generate , there is a option to generate data model from it.
But it is dimmed. Is there any precondition to achieve before this option become possible.
Thanks in advance .

The link you mentioned has the Prerequisites,
Do include all the jar in you path.
It will resolve all your issues.

Problem during call java class (model layer) from jsp page (view layer)

I created new Fusion web application so I have now to parts in the application navigator (model, viewcontroller)
I want to write java class in the Model part as following:
package persistence;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DBManager {
Connection connection = null;
public DBManager() {
super();
public void init() {
try {
// Load the JDBC driver
String driverName = "oracle.jdbc.driver.OracleDriver";
Class.forName(driverName);
// Create a connection to the database
String serverName = Constant.DB_SERVER_NAME;
String portNumber = Constant.DB_PORT_NUMBER;
String sid = Constant.DB_SID;
String url =
"jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" +
sid;
String username = Constant.DB_USER_NAME;
String password = Constant.DB_PASSWORD;
connection = DriverManager.getConnection(url, username, password);
System.out.println("*");
System.out.println(connection.getCatalog());
} catch (ClassNotFoundException e) {
System.out.println("Could not find the database driver");
} catch (SQLException e) {
System.out.println("Could not connect to the database");
e.printStackTrace();
and wrote JSP page in the view controller part as following :
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<%@page import="persistance.*"%>
<% persistance.DBManager manager = new DBManager(); %>
<%@ page contentType="text/html;charset=windows-1252"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252"/>
<title>Browse</title>
</head>
<body>
<table>
</table>
</body>
</html>
but this I have the following error in the jsp page :type persistance.DBManager not found
my job is to build simple ADF application using JSF and java without any ADF faces or JPA or any another technology
thanks

Duplicate message.
type persistance.DBManager not found
Add a Dependency on the Model project in the View project. In Project Properties select the Dependencies node to add dependencies.
Edited by: dvohra16 on Jun 19, 2011 8:37 AM

Model Problem In webdynpro java

Hi all,
I am facing a differnent problem with model classes in my webdynpro application.
I have a componenet where in i am using standard BAPIs.The problem here is i am getting the latest data from the bapi only when the application is loded first.
If i add a new record and want to know the size of output node it is not giving the latest one.It is showing the size it has when the application is loded,But in the backend it is getting updated everytime.
What might me the problem for this??Is it that the model proxy classes that are loded when the application is loded is not getting refreshed??
Edited by: chandrashekar chandrashekar on Dec 10, 2008 7:30 AM

Hi,
This is the code i am using...
My problem in brief is if i try to add a record it is getting updated in SAP but if i try to display the output node it is giving the size it has when the application is loded.
If i restart the application it is giving the updated sise of the output node
Bapi_Class_Getdetail_Input inputGetDetail = null;
inputGetDetail = new Bapi_Class_Getdetail_Input();
wdContext.nodeBapi_Class_Getdetail_Input().bind(inputGetDetail);
inputGetDetail.setClassnum(className);
inputGetDetail.setClasstype("300");
     try
          executeBapi_Class_GetDetail();
     catch(WDDynamicRFCExecuteException ex)
          return false;
executeBapi_Class_GetDetail()
try
wdContext.currentBapi_Class_Getdetail_InputElement().modelObject().execute();
wdContext.nodeOutput().invalidate();
catch(WDDynamicRFCExecuteException ex)
     ex.printStackTrace();

Invalid Class Exception problem

Hi whenever i try to run this method from a different class to the one it is declared in it throws invalid class exception, (in its error it says the class this method is written in is the problem) yet when i run it from its own class in a temporary main it works fine, perhaps someone can see the problem in the method code. All its doing is reading from a few different txt files, deserializing the objects and putting them into arraylists for future access.
public void readCourseData()
          CourseArrayLengths cal;
          try
               FileInputStream fis = new FileInputStream("arraylengths.txt");
               ObjectInputStream ois = new ObjectInputStream(fis);
               cal = ((CourseArrayLengths) ois.readObject());
               ois.close();
               FileInputStream fis1 = new FileInputStream("units.txt");
               ObjectInputStream ois1 = new ObjectInputStream(fis1);
               for(int i=0;i<cal.getUnitArrayLength();i++)
                    units.add((Unit) ois1.readObject());
               ois1.close();
               FileInputStream fis2 = new FileInputStream("sections.txt");
               ObjectInputStream ois2 = new ObjectInputStream(fis2);
               for(int i=0;i<cal.getSectionArrayLength();i++)
                    sections.add((Section) ois2.readObject());
               ois2.close();
               FileInputStream fis3 = new FileInputStream("files.txt");
               ObjectInputStream ois3 = new ObjectInputStream(fis3);
               for(int i=0;i<cal.getFileArrayLength();i++)
                    files.add((Filetype) ois3.readObject());
               ois3.close();
          catch(FileNotFoundException exception)
          System.out.println("The File was not found");
          catch(IOException exception)
          System.out.println(exception);
          catch(ClassNotFoundException exception)
          System.out.println(exception);
     }

import java.util.ArrayList;
import java.io.*;
import javax.swing.*;
public class Unit implements Serializable
ArrayList units = new ArrayList();
ArrayList sections = new ArrayList();
ArrayList files = new ArrayList();
String unitName;
int sStart=0,sEnd=0,sIndex=0,fIndex=0,subIndex=0;
     public Unit(String unitNamec,int sStartc,int sEndc)
          unitName = unitNamec;
          sStart = sStartc;
          sEnd = sEndc;
     public Unit()
     public String getUnitName()
          return unitName;
     public Unit getUnit(int i)
          return (Unit)units.get(i);
     public Section getSection(int i)
          return (Section)sections.get(i);
     public ArrayList getUnitArray()
          return units;
     public int getSectionStart()
          return sStart;
     public int getSectionEnd()
          return sEnd;
     public void setSectionStart(int i)
          sStart = i;
     public void setSectionEnd(int i)
          sEnd = i;
     public void addUnit(String uName)
          units.add(new Unit(uName,sections.size(),sIndex));
          sIndex++;
     public void addSection(String sName,Unit u)
          //problem lies with files.size()
          sections.add(new Section(sName,files.size(),files.size()));
          u.setSectionEnd(u.getSectionEnd()+1);
          //fIndex++;
     public void addFile(String fName,File fPath,Section s)
          files.add(new Filetype(fName,fPath));
          s.setFileEnd(s.getFileEnd()+1);
     public void display(Unit u)
          System.out.println(u.getUnitName());
          for(int i=u.getSectionStart();i<u.getSectionEnd();i++)
               System.out.println(((Section)sections.get(i)).getSectName());
               for(int j=((Section)(sections.get(i))).getFileStart();j<((Section)(sections.get(i))).getFileEnd();j++)
                    System.out.println(((Filetype)files.get(j)).getFileName());
     public void writeCourseData()
     //writes 3 arrays to 3 different files
try
FileOutputStream fos = new FileOutputStream("units.txt");
ObjectOutputStream oos = new ObjectOutputStream(fos);
     for(int i=0;i<units.size();i++)
     oos.writeObject((Unit)units.get(i));
     oos.close();
catch (Exception e)
System.err.println ("Error writing to file");
try
FileOutputStream fos = new FileOutputStream("sections.txt");
ObjectOutputStream oos = new ObjectOutputStream(fos);
     for(int i=0;i<sections.size();i++)
     oos.writeObject((Section)sections.get(i));
     oos.close();
catch (Exception e)
System.err.println ("Error writing to file");
try
FileOutputStream fos = new FileOutputStream("files.txt");
ObjectOutputStream oos = new ObjectOutputStream(fos);
     for(int i=0;i<files.size();i++)
     oos.writeObject((Filetype)files.get(i));
     oos.close();
catch (Exception e)
System.err.println ("Error writing to file");
try
FileOutputStream fos = new FileOutputStream("arraylengths.txt");
ObjectOutputStream oos = new ObjectOutputStream(fos);
     oos.writeObject(new CourseArrayLengths(units.size(),sections.size(),files.size()));
     oos.close();
catch (Exception e)
System.err.println ("Error writing to file");
     public void readCourseData()
          CourseArrayLengths cal;
          try
               FileInputStream fis = new FileInputStream("arraylengths.txt");
               ObjectInputStream ois = new ObjectInputStream(fis);
               cal = ((CourseArrayLengths) ois.readObject());
               ois.close();
               FileInputStream fis1 = new FileInputStream("units.txt");
               ObjectInputStream ois1 = new ObjectInputStream(fis1);
               for(int i=0;i<cal.getUnitArrayLength();i++)
                    units.add((Unit) ois1.readObject());
               ois1.close();
               FileInputStream fis2 = new FileInputStream("sections.txt");
               ObjectInputStream ois2 = new ObjectInputStream(fis2);
               for(int i=0;i<cal.getSectionArrayLength();i++)
                    sections.add((Section) ois2.readObject());
               ois2.close();
               FileInputStream fis3 = new FileInputStream("files.txt");
               ObjectInputStream ois3 = new ObjectInputStream(fis3);
               for(int i=0;i<cal.getFileArrayLength();i++)
                    files.add((Filetype) ois3.readObject());
               ois3.close();
          catch(FileNotFoundException exception)
          System.out.println("The File was not found");
          catch(IOException exception)
          System.out.println(exception);
          catch(ClassNotFoundException exception)
          System.out.println(exception);
     /*public static void main(String args[])
          Unit u1 = new Unit();
          u1.addUnit("Cmps2a22");
          u1.addSection("Section1",u1.getUnit(0));
          //u1.addSubSection("Subsect1",u1.getSection(0));
          u1.addFile("File1",null,u1.getSection(0));
          u1.addFile("File2",null,u1.getSection(0));
          u1.addSection("Section2",u1.getUnit(0));
          u1.addFile("NF",null,u1.getSection(1));
          u1.addFile("NF2",null,u1.getSection(1));
          u1.addFile("NF3",null,u1.getSection(1));
          u1.addSection("Section3",u1.getUnit(0));
          u1.addFile("NF",null,u1.getSection(2));
          u1.addFile("NF2",null,u1.getSection(2));
          u1.addFile("NF4",null,u1.getSection(2));
          u1.display(u1.getUnit(0));
          u1.writeCourseData();
          u1.readCourseData();
          u1.display(u1.getUnit(0));
import java.util.ArrayList;
import java.io.*;
public class Section implements Serializable
private String sectName,subSectName;
private int fpStart=0,fpEnd=0,subSectStart=0,subSectEnd=0;
private Section s;
private boolean sub;
     public Section(String sectNamec,int fpStartc,int fpEndc,int subSectStartc,int subSectEndc,Section sc,boolean subc)
          sectName = sectNamec;
          fpStart = fpStartc;
          fpEnd = fpEndc;
          subSectStart = subSectStartc;
          subSectEnd = subSectEndc;
          s = sc;
          sub = subc;
     public Section(String sectNamec,int fpStartc,int fpEndc)
          sectName = sectNamec;
          fpStart = fpStartc;
          fpEnd = fpEndc;
     public Section getParent()
          return s;
     public boolean isSub()
          return sub;
     public String getSubName()
          return subSectName;
     public int getSubStart()
          return subSectStart;
     public int getSubEnd()
          return subSectEnd;
     public void setSubStart(int i)
          subSectStart = i;
     public void setSubEnd(int i)
          subSectEnd = i;
     public int getFileStart()
          return fpStart;
     public int getFileEnd()
          return fpEnd;
     public String getSectName()
          return sectName;
     public void setFileStart(int i)
          fpStart = i;
     public void setFileEnd(int i)
          fpEnd = i;
     public void addSection(String sectName)
     /*public static void main(String args[])
import java.io.*;
public class Filetype implements Serializable
     private String name;
     private File filepath;
     public Filetype(String namec, File filepathc)
          name = namec;
          filepath = filepathc;
     public String getFileName()
          return name;
     public File getFilepath()
          return filepath;
import java.io.*;
public class CourseArrayLengths implements Serializable
private int ul,sl,fl;
     public CourseArrayLengths(int ulc,int slc,int flc)
          ul = ulc;
          sl = slc;
          fl = flc;
     public int getUnitArrayLength()
          return ul;
     public int getSectionArrayLength()
          return sl;
     public int getFileArrayLength()
          return fl;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.io.*;
public class OrganiserGui implements ActionListener
int width,height;
JFrame frame;
     public OrganiserGui()
          width = 600;
          height = 500;
     public void runGui()
          //Frame sizes and location
          frame = new JFrame("StudentOrganiser V1.0");
frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
          frame.setSize(width,height);
          frame.setLocation(60,60);
          JMenuBar menuBar = new JMenuBar();
          //File menu
          JMenu fileMenu = new JMenu("File");
          menuBar.add(fileMenu);
          fileMenu.addSeparator();
          JMenu addSubMenu = new JMenu("Add");
          fileMenu.add(addSubMenu);
          JMenuItem cwk = new JMenuItem("Coursework assignment");
          addSubMenu.add(cwk);
          JMenuItem lecture = new JMenuItem("Lecture");
          lecture.addActionListener(this);
          addSubMenu.add(lecture);
          JMenuItem seminar = new JMenuItem("Seminar sheet");
          addSubMenu.add(seminar);
          //Calendar menu
          JMenu calendarMenu = new JMenu("Calendar");
          menuBar.add(calendarMenu);
          calendarMenu.addSeparator();
          JMenu calendarSubMenu = new JMenu("Edit Calendar");
          calendarMenu.add(calendarSubMenu);
          JMenuItem eventa = new JMenuItem("Add/Remove Event");
          eventa.addActionListener(this);
          calendarSubMenu.add(eventa);
          JMenuItem calClear = new JMenuItem("Clear Calendar");
          calClear.addActionListener(this);
          calendarSubMenu.add(calClear);
          JMenu calendarSubMenuView = new JMenu("View");
          calendarMenu.add(calendarSubMenuView);
          JMenuItem year = new JMenuItem("By Year");
          year.addActionListener(this);
          calendarSubMenuView.add(year);
          JMenuItem month = new JMenuItem("By Month");
          month.addActionListener(this);
          calendarSubMenuView.add(month);
          JMenuItem week = new JMenuItem("By Week");
          week.addActionListener(this);
          calendarSubMenuView.add(week);
          //Timetable menu
          JMenu timetableMenu = new JMenu("Timetable");
          menuBar.add(timetableMenu);
          timetableMenu.addSeparator();
          JMenu stimetableSubMenu = new JMenu("Social Timetable");
          timetableMenu.add(stimetableSubMenu);
          JMenu ltimetableSubMenu = new JMenu("Lecture Timetable");
          timetableMenu.add(ltimetableSubMenu);
          frame.setJMenuBar(menuBar);
frame.setVisible(true);
     public void actionPerformed(ActionEvent e)
          JMenuItem source = (JMenuItem)(e.getSource());
          System.out.println(source.getText());
          Calendar c = new Calendar();
          if(source.getText().equalsIgnoreCase("By Year"))
               System.out.println("INSIDE");
               c.buildArray();
               c.calendarByYear(Calendar.calendarArray);
          if(source.getText().equalsIgnoreCase("Add/Remove Event"))
               c.eventInput();
          if(source.getText().equalsIgnoreCase("clear calendar"))
               c.buildYear();
               c.writeEvent(Calendar.calendarArray);
               c.buildArray();
          if(source.getText().equalsIgnoreCase("lecture"))
               System.out.println("Nearly working");
               //JFileChooser jf = new JFileChooser();
               //jf.showOpenDialog(frame);
               FileManager fm = new FileManager();
               //choose unit to add file to
               JOptionPane unitOption = new JOptionPane();
               Unit u = new Unit();
               u.readCourseData();
               //u.display(u.getUnit(0));
               System.out.println((u.getUnit(0)).getUnitName());
               String[] unitNames = new String[u.getUnitArray().size()];
               for(int i=0;i<unitNames.length;i++)
                    //unitNames[i] = (((Unit)u.getUnitArray().get(i)).getUnitName());
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                    System.out.println((u.getUnit(i)).getUnitName());
               //unitOption.showInputDialog("Select Unit to add lecture to",unitNames);
               //needs to select where to store it
               //fm.openFile(jf.getSelectedFile());
     public static void main(String args[])
          OrganiserGui gui = new OrganiserGui();
          gui.runGui();
java.io.invalidclassexception: Unit; local class incompatible: stream classdesc serialversionUID = 3355176005651395533, local class serialversionUID = 307309993874795880

Web Service From Java class, serialization problem

Hi,
I want to create Web Service from Java class, I made java project, generated web service from it, create web service archive project and deployed it to WAS 6.40.
My class have 2 methods,
public int add(int a, int b);
public MyResponse doSomthing(MyRequest req);
I can succesfully call add method from Web Service Navigator, it works fine but when I call doSomthing methods I get the following error:
<b>
Deserializing fails. Nested message: XML Deserialization Error. Result class [com.mycomp.sap_tech.ws.MyRequest] does not have property [Amount] of type [java.lang.String]. It is required to load XML..
</b>
Any ideas how to resolve it?
P.S. MyRequest class is exposed throw VI, has default constractor and public getters and setters for all properties. It implements Serializable as well. Any guesses?
Thanks in advance,
Victor.

Hi Bhavik, thanks for response.
as I already mentioned it implements Serializable, so it is not the problem.
Thanks Avi but it didn't helps iether
Victor

Class visibility problems in deployed OC4J application

I have an entity, autogenerated from a database table by JDeveloper, which has the form:
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import ...
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@NamedQuery( ... )
@Table( ... )
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}Then I have a stateless session bean, also autogenerated by JDeveloper, which has the form:
SessionEJBBean.java:
package a.b.c;
import ...
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    private EntityManager em;
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package a.b.c;
import ...
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<?xml version="1.0" encoding="windows-1252" ?>
<persistence
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0" xmlns="http://java.sun.com/xml/ns/persistence">
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11-Jun-2007 16:32:17 oracle.j2ee.rmi.RMIMessages
EXCEPTION_ORIGINATES_FROM_THE_REMOTE_SERVER
WARNING: Exception returned by remote server: {0}
javax.ejb.EJBException: Exception [TOPLINK-28006]
(Oracle TopLink Essentials - 2006.8 (Build 060829)):
oracle.toplink.essentials.exceptions.EntityManagerSetupException
Exception Description: ClassNotFound: [a.b.c.Customizer]
specified in [toplink.session.customizer] property.
Internal Exception: oracle.classloader.util.AnnotatedClassNotFoundException:
       Missing class: com.logicacmg.security.Customizer
     Dependent class: oracle.toplink.essentials.internal.security.PrivilegedAccessHelper
              Loader: oracle.persistence:1.0
         Code-Source: /usr/oc4j/toplink/jlib/toplink-essentials.jar
       Configuration: <code-source> in /usr/oc4j/j2ee/home/config/server.xml
This load was initiated at oracle.persistence:1.0 using the Class.forName() method.
The missing class is available from the following locations:
     1. Code-Source: /usr/oc4j/j2ee/home/applications/SimpleApp/SimpleApp.jar
(from <ejb> in /usr/oc4j/j2ee/home/applications/SimpleApp)
        This code-source is available in loader SimpleApp.root:0.0.0.
This is the current thread's context loader, and it appears that Class.forName()
was used to load the dependent class. If a loader was not explicitly passed to
Class.forName(), try passing the result of calling
Thread.currentThread().getContextClassLoader()So, my question is: what is the correct way for me to configure the system so that my Customizer class is picked up?
Apologies if this is obvious - I'm still rather new to working in this area (so if anything else I've written doesn't make sense - please don't be afraid to point it out!).
Regards,
Alistair.

Hi, you all seem highly intelligent so I'll give this a shot.
We're having a similar problem, but TopLink is not involved. Axis2 is, but in our case, the Axis2 application runs fine, it's the other applications that fail.
We have three applications, Login, Candle, and Webservices (the one with Axis2). When we first start up the applications, they all instantiate fine. We can run Login pages and Candle pages fine. We can also run non-Axis2 Webservices servlets without breaking Login and Candle. But when we run a webservices servlet that uses Axis2, something happens that causes all future Login and Candle class loading to fail! From the error message, OC4J indicates that it is trying to load classes for Login and Candle using the classloader for Webservices.
So, to summarize, once the webservices app runs an Axis2 servlet, OC4J tries to use the webservices' classloader to load classes for the other applications instead of using their classloaders. The example error message I give below is for the Candle application, but the same problem occurs for Login.
Please help, even if it's just a suggestion for something to try!! We've been trying to understand this for 2 days and we're still as stumped as ever.
[java] 2007-06-15 14:59:59,159 ERROR [org.apache.struts.action.RequestProcessor] - No action instance for path /adpThrowableHandler could be created
[java] oracle.classloader.util.AnnotatedClassNotFoundException:
[java] Missing class: com.adp.candle.core.ui.struts.exceptionhandler.AdpThrowableHandlerAction
[java] Dependent class: org.apache.struts.util.RequestUtils
[java] Loader: default.web.candle:0.0.0
[java] Code-Source: /C:/build/javaroot/candle/WEB-INF/lib/struts.jar
[java] Configuration: WEB-INF/lib/ directory in C:\build\javaroot\candle\WEB-INF\lib
[java] This load was initiated at default.web.webservices:0.0.0 using the loadClass() method.
[java] The missing class is available from the following locations:
[java] 1. Code-Source: /C:/build/javaroot/candle/WEB-INF/classes/ (from WEB-INF/classes/ in C:\build\javaroot\candle\WEB-INF\classes)
[java] This code-source is available in loader default.web.candle:0.0.0.
-- Brad

Application Class Loader problem calling virtual function

Hello everyone
I have run in to very strange behavior of JVM
I have created a class loader which allows my to load classes from
jar file, regardless that URLClassLoader supplies this functionality.
I am using this class loader to load some classes and call their virtual functions. The class diagram looks like that:
public interface I {
   public void init();
public class AAA implements
   public void init(){
public class BBB extends AAA{
   public void init(){
      //here comes implementation
}Interface I and class AAA are loaded with System Class loader and Class BBB is loaded using my class loader from jar file.
ByteStreamClassLoader classLoader = new ByteStreamClassLoader ();
Class cl = classLoader. loadClass(�com.product.BBB�,true);
I myInterface = cl.newInstance();
myInterface.init();The problem is that from some unknown reason java class AAA.init() instead of BBB.init().
Can somebody help me what am I doing wrong?
Class Loader code attached below
public class ByteStreamClassLoader   extends ClassLoader {
    protected HashMap m_cache = new HashMap();
    public void clearCashe() {
      m_cache = new HashMap();
    private String definePackage(String className) {
      StringBuilder strB = new StringBuilder();
      //Class name must be removed from the URI in order to define a package
      String[] packageArray = className.split("\\.");
      for (int i = 0; i < packageArray.length - 1; i++) {
        strB.append(packageArray).append(".");
String packageName = strB.toString();
packageName = packageName.substring(0, packageName.length() - 1);
if (getPackage(packageName) == null) {
m_logger.log(Level.FINEST, "Defining package '" + packageName + "'");
definePackage(packageName, null, null, null, null, null, null, null);
return packageName;
public synchronized Class loadClass(String name, boolean resolve) throws
ClassNotFoundException {
name = name.replaceAll("/", ".").replaceAll(".class", "");
//Try to locate the Class in cashe
Class c = (Class) m_cache.get(name);
//Try to locate the Class in the System Class Loader
if (c == null) {
try {
c = ClassLoader.getSystemClassLoader().loadClass(name);
catch (Exception ex) {}
else {
m_logger.log(Level.FINEST, "Class '" + name + "' found in cache");
//Load the class from byte array
if (c == null) {
String resourceName = name;
if (!resourceName.endsWith(".class")) {
resourceName = resourceName.concat(".class");
//Retrieve class byte representation
if (resourceName.indexOf(".") != -1) {
resourceName =
resourceName.replaceAll("\\.", "/").replaceAll("/class", ".class");
//Use the ByteStreamClassLoader to load the class from byte array
byte[] classByteArray = null;
try {
classByteArray = getResourceBytes(resourceName);
catch (IOException ex1) {
throw new ClassNotFoundException(
"Could not load class data." + ex1.getMessage());
m_logger.log(
Level.FINEST, "Loading class '" +
name + "' Byte Length: " + classByteArray.length);
String p = definePackage(name);
c = defineClass(
name,
classByteArray,
0,
classByteArray.length,
ByteStreamClassLoader.class.getProtectionDomain());
m_cache.put(name, c);
if (resolve) {
resolveClass(c);
return c;

Hello everyone
I have run in to very strange behavior of JVM
I have created a class loader which allows my to load classes from
jar file, regardless that URLClassLoader supplies this functionality.
I am using this class loader to load some classes and call their virtual functions. The class diagram looks like that:
public interface I {
   public void init();
public class AAA implements
   public void init(){
public class BBB extends AAA{
   public void init(){
      //here comes implementation
}Interface I and class AAA are loaded with System Class loader and Class BBB is loaded using my class loader from jar file.
ByteStreamClassLoader classLoader = new ByteStreamClassLoader ();
Class cl = classLoader. loadClass(�com.product.BBB�,true);
I myInterface = cl.newInstance();
myInterface.init();The problem is that from some unknown reason java class AAA.init() instead of BBB.init().
Can somebody help me what am I doing wrong?
Class Loader code attached below
public class ByteStreamClassLoader   extends ClassLoader {
    protected HashMap m_cache = new HashMap();
    public void clearCashe() {
      m_cache = new HashMap();
    private String definePackage(String className) {
      StringBuilder strB = new StringBuilder();
      //Class name must be removed from the URI in order to define a package
      String[] packageArray = className.split("\\.");
      for (int i = 0; i < packageArray.length - 1; i++) {
        strB.append(packageArray).append(".");
String packageName = strB.toString();
packageName = packageName.substring(0, packageName.length() - 1);
if (getPackage(packageName) == null) {
m_logger.log(Level.FINEST, "Defining package '" + packageName + "'");
definePackage(packageName, null, null, null, null, null, null, null);
return packageName;
public synchronized Class loadClass(String name, boolean resolve) throws
ClassNotFoundException {
name = name.replaceAll("/", ".").replaceAll(".class", "");
//Try to locate the Class in cashe
Class c = (Class) m_cache.get(name);
//Try to locate the Class in the System Class Loader
if (c == null) {
try {
c = ClassLoader.getSystemClassLoader().loadClass(name);
catch (Exception ex) {}
else {
m_logger.log(Level.FINEST, "Class '" + name + "' found in cache");
//Load the class from byte array
if (c == null) {
String resourceName = name;
if (!resourceName.endsWith(".class")) {
resourceName = resourceName.concat(".class");
//Retrieve class byte representation
if (resourceName.indexOf(".") != -1) {
resourceName =
resourceName.replaceAll("\\.", "/").replaceAll("/class", ".class");
//Use the ByteStreamClassLoader to load the class from byte array
byte[] classByteArray = null;
try {
classByteArray = getResourceBytes(resourceName);
catch (IOException ex1) {
throw new ClassNotFoundException(
"Could not load class data." + ex1.getMessage());
m_logger.log(
Level.FINEST, "Loading class '" +
name + "' Byte Length: " + classByteArray.length);
String p = definePackage(name);
c = defineClass(
name,
classByteArray,
0,
classByteArray.length,
ByteStreamClassLoader.class.getProtectionDomain());
m_cache.put(name, c);
if (resolve) {
resolveClass(c);
return c;

Plz help me out with class loader problem

hai forum members,
I have a code which loads class files from local disk.
It works fine with some classes ,
But i get this exception when i am selecting certain other class files
I am using jdeveloper.
Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: Filter (wrong name: project1/Filter)
     at java.lang.ClassLoader.defineClass1(Native Method)
     at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
     at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
     at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
     at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
     at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
     at java.security.AccessController.doPrivileged(Native Method)
     at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
     at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
     at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
     at com.jutframe.JavaUnitTester.selectClass_actionPerformed(JavaUnitTester.java:449)
     at com.jutframe.JavaUnitTester$7.actionPerformed(JavaUnitTester.java:338)
     at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1849)
     at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2169)
     at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
     at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
     at javax.swing.AbstractButton.doClick(AbstractButton.java:302)
     at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1000)
     at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:1041)
     at java.awt.Component.processMouseEvent(Component.java:5488)
     at javax.swing.JComponent.processMouseEvent(JComponent.java:3093)
     at java.awt.Component.processEvent(Component.java:5253)
     at java.awt.Container.processEvent(Container.java:1966)
     at java.awt.Component.dispatchEventImpl(Component.java:3955)
     at java.awt.Container.dispatchEventImpl(Container.java:2024)
     at java.awt.Component.dispatchEvent(Component.java:3803)
     at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4212)
     at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3892)
     at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3822)
     at java.awt.Container.dispatchEventImpl(Container.java:2010)
     at java.awt.Window.dispatchEventImpl(Window.java:1766)
     at java.awt.Component.dispatchEvent(Component.java:3803)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:234)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
                    JFileChooser jfilechooser=new JFileChooser();
                    Filterclass filter=new Filterclass();
                    //Set selection mode for file chooser
                    jfilechooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
                    //set file filter
                    jfilechooser.setFileFilter(filter);
                    int returnVal = jfilechooser.showOpenDialog(this);
                    if(returnVal == JFileChooser.APPROVE_OPTION)
                        try
                                String str = jfilechooser.getSelectedFile().getName();
                                String parent=jfilechooser.getSelectedFile().getParent();
                                 // Create a File object on the root of the directory containing the class file
                                 File file = new File(parent);
                                 // Convert File to a URL
                                 URL url = file.toURL();
                                 URL[] urls = new URL[]{url};
                                 // Create a new class loader with the directory
                                 ClassLoader cl = new URLClassLoader(urls);
                                 StringTokenizer st = new StringTokenizer(str,".");
                                 String s = st.nextToken ();
                                 Class c = cl.loadClass(s); //ERROR IS SHOWN IN THIS PARTICULAR LINE
                                 Object instance=c.newInstance();
--------------------------------------------please help me trace my mistake.
thank you all.

i think the problem that i have set a particular class path for my class files and my application loads files from that alone.
So plz tell me if theres any way to access the class path of a particular file dynamically?
regards

WebLog 9 Class loader problem with an Inbound Resource Adapter

The following code
          MessageEndpoint messageEndPoint = null;
          InboundListener listener = null;
          messageEndPoint = this.messageEndpointFactory.createEndpoint(null);
          listener = (InboundListener) messageEndPoint;
          causes a ClassCastException as the Listener class is packaged both in the ResourceAdapter and in the EAR
          holding the MessageDrivenBean: same class but two
          different class loaders !
          How can I solve this problem ?

Turning on Debugging, found the problem:
          <[JCABindingManager] activationSpec=null>
          <[JCABindingManager] The activationSpec is null, deActivation is skipped>
          In the application.xml, I had
          1. ejb (mdb) module and then
          2. connector module
          Changed the application.xml to
          1. connector module and then
          2. ejb (mdb) module
          container then called endpointDeactivation on undeployment.

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 load problem..

Hello all,
I am rather new to this concept of creating class loaders.
I started on a simple test and landed into a problem right away. I have a Java class file stuffed away somewhere on m machine (at a location not on my CLASSPATH) . I just want to load that class dynamically. Here is my humble code :
import java.io.*;
public class DynamicClassLoadTest extends ClassLoader {
     String classFileName;
     String pathToClassFile;
     public static void main(String[] args) {
          try {
               if(args.length != 2) {
                    System.out.println("Usage : java DynamicClassLoadTest <path to class file> <name of class file>");
                    System.exit(0);
               System.out.println("MISSION: To dynamically load class " + args[1] + " from path : " + args[0]);
               DynamicClassLoadTest dcl = new DynamicClassLoadTest();
               Class cls = dcl.loadClass(args[1], args[0], true);
          catch(Exception e) {
               System.out.println("Mission failed with error : " + e);
               e.printStackTrace();
     public Class loadClass(String name, String path, boolean resolve)
          throws ClassNotFoundException
          this.pathToClassFile=path;
          this.classFileName= name;
          return (loadClass(name, resolve));
     public Class loadClass(String name, boolean resolve)
          throws ClassNotFoundException
          try {
               File f = new File(pathToClassFile, name + ".class");
               if(!f.exists())
                    throw new ClassNotFoundException("Specified class not found");
               FileInputStream fis = new FileInputStream(f);
               long fileSize = f.length();
               System.out.println("Size of class file = " + fileSize);
               byte[] classBytes = new byte[(int) fileSize];
               int r = fis.read(classBytes);
               System.out.println("Bytes read is " + r + " and file size is " + fileSize + " and byte array length is " + classBytes.length);
               Class c = defineClass(name, classBytes, 0, classBytes.length);
               System.out.println("CLASS created..");
               return c;
          catch(Exception e) {
               throw new ClassNotFoundException(e.getMessage());
When I execute as :
java DynamicClassLoadTest /Users/user1 JustTest
the below is printed on execution :
MISSION: To dynamically load class JustTest from path : /Users/user1
Size of class file = 421
Bytes read is 421 and file size is 421 and byte array length is 421
Exception in thread "main" java.lang.NoClassDefFoundError: java/lang/Object
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:502)
at java.lang.ClassLoader.defineClass(ClassLoader.java:431)
at DynamicClassLoadTest.loadClass(DynamicClassLoadTest.java:56)
at DynamicClassLoadTest.loadClass(DynamicClassLoadTest.java:33)
at DynamicClassLoadTest.main(DynamicClassLoadTest.java:18)
The class file has apparently been read fine - then why is this java/lang/object reference ?
Any tips would be of huge help.
Thanks.

An extension to this.
What should I do when I have to load a jar dynamically ? I manage to load the main class of the jar successfully. But what about classes in the jar which are invoked by this class. Say we have case as below :
JustAJar.jar contains :
sh-2.05a$ jar tvf JustAJar.jar
0 Fri May 23 14:41:14 PDT 2003 META-INF/
70 Fri May 23 14:41:14 PDT 2003 META-INF/MANIFEST.MF
567 Fri May 23 14:40:52 PDT 2003 InvokeTheNext.class
475 Fri May 23 14:40:52 PDT 2003 InvokeMe.class
Now, InvokeMe is the class I instantiate :
public class InvokeMe {
public static void main(String[] args) {
System.out.println("Welcome to InvokeMe");
InvokeTheNext itn = new InvokeTheNext("InvokeMe");
InvokeTheNext is :
public class InvokeTheNext {
public InvokeTheNext(String str) {
System.out.println("Welcome to InvokeTheNext");
System.out.println("Recd ur msg " + str);
Now I manage to define and resolve the class InvokeMe, but when the class is invoked, the foll error is thrown :
Resolved class with name InvokeMe successfully
Welcome to InvokeMe
Mission failed with error : java.lang.reflect.InvocationTargetException
java.lang.reflect.InvocationTargetException
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:324)
     at InvokeForClassLoad.main(InvokeForClassLoad.java:46)
Caused by: java.lang.NoClassDefFoundError: InvokeTheNext
     at InvokeMe.main(InvokeMe.java:4)
I tried loading the entire jar file into the CLASSPATH dynamically (using System.setProperty) but that doesnt help. Any inputs please ?
Thanks.

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