Loading a class via reflection without knowing the full qualified path ?

Question

Hi there
I d like to load a class via reflection and call the constructor of the class object. My problem is that I dont know the full qulified name e.g. org.xyz.Classname bur only the Classname.
I tried different things but none seem to work:
     1. Class c = Class.forName("Classname");  //does not suffice, full qualified name required
2. ClassLoader classloader = java.lang.ClassLoader.getSystemClassLoader();
         try {
           Class cl = classloader.loadClass(stripFileType(Filename));//if i do not pass the full qualified name i get a ClassNotFoundException
3. I tried to consruct a class object with my own classloader , calling:
          Class cl = super.defineClass(null, b, 0, b.length );     b is of type byte[]This almost works. I get a class Object without knowing the full qulified path. I can transform a filename into a raw array of bytes and I get the class out of it. But there is still a problem: If there are more than on classes defined in the same textfile I get an InvocationTargetException.
It looks like this:
package org.eml.adaptiveUI.demo;
import com.borland.jbcl.layout.*;
import java.awt.*;
import org.eml.adaptiveUI.layout.*;
import javax.swing.*;
import java.awt.event.*;
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2003</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
public class twoButtons extends JFrame {
  SPanel sPanel1 = new SPanel();
  JButton jButton1 = new JButton();
  GridBagLayout gridBagLayout1 = new GridBagLayout();
  GridBagLayout gridBagLayout2 = new GridBagLayout();
  public twoButtons() throws HeadlessException {
    try {
      jbInit();
    catch(Exception e) {
      e.printStackTrace();
  public static void main(String args[]){
    twoButtons twob = new twoButtons();
    twob.pack();
    twob.show();
  private void jbInit() throws Exception {
    this.getContentPane().setLayout(gridBagLayout1);
    jButton1.setText("button 1");
    jButton1.addActionListener(new TransformationDemo_jButton1_actionAdapter(this));
    this.getContentPane().add(sPanel1,  new GridBagConstraints(0, 0, 1, 1, 1.0, 1.0
            ,GridBagConstraints.CENTER, GridBagConstraints.BOTH, new Insets(57, 52, 94, 108), 35, 44));
    sPanel1.add(jButton1,  new GridBagConstraints(0, 0, 1, 1, 0.0, 0.0
            ,GridBagConstraints.CENTER, GridBagConstraints.NONE, new Insets(5, 41, 0, 0), 0, 0));
  void jButton1_actionPerformed(ActionEvent e) {
    System.out.println("button 1 source: " + e.getSource());
    System.out.println("d: " + e.getID());
   System.out.println("/n commmand: " + e.getActionCommand());
class TransformationDemo_jButton1_actionAdapter implements java.awt.event.ActionListener {
  twoButtons adaptee;
  TransformationDemo_jButton1_actionAdapter(twoButtons adaptee) {
    this.adaptee = adaptee;
  public void actionPerformed(ActionEvent e) {
    adaptee.jButton1_actionPerformed(e);
}As you can see there is the class TransformationDemo_jButton1_actionAdapter class defined in the same classfile. The problem is now that the twoButtons constructor calls the TransfomationDemo_jButton1_actionAdapter constructor and this leads to InvocationTargetException. I dont know if this is a java bug because it should be possible.
Can you help me?

Answer 1

hi thanks at first,
the thing you mentioned could be a problem, but I dont think it is.
If I have the full qualified name (which I havent) then everything goes normal. I only have to load the "twoButtons" class and not the other (actionadapter class), so I dont think this is the point. In this case the twoButtons constructor constructs an object of the actionadapter class and everything goes well. The bad thing is though that I do not have the full qulified name :(
Invocation target exception tells me (in own words): Tried to acces the constructor of the actionadapter class (which is not public) out of class reflectionTest class .
reflectionTest is the class where the reflection stuff happens and the twoButttons class is defineClass() ed.
The problem is, only twoButtons class has the rights to call methods from the actionadapter class, the reflection class does not. BUT: I do not call the actionadapter methods from the reflection class. I call them only from the twoButtons class.
I hope somebody understands my problem :)