private Vector alreadyNotified = new Vector(); 
private boolean firstCall = true; 
private TreeParent root = null; 

private void recursivePluginDependencyWalker(PluginData pdObject,  
     TreeParent parentNode){ 

 try { 
  String path = pdObject.getPluginLocation(); 
  PluginParser pp = null; 
  File pluginDotXmlFile = new File(path + "/plugin.xml"); 
  if(pluginDotXmlFile.exists()){ 
   pp = new PluginParser(pluginDotXmlFile); 
  }else{ 
   File fragmentDotXmlFile = new File(path +  
    "/fragment.xml"); 
   if(fragmentDotXmlFile.exists()){ 
    pp = new PluginParser(fragmentDotXmlFile); 
   }else{ 
    return;//no plugin.xml or fragment.xml found 
   }  
  } 

  String displayName = pdObject.getDisplayName(); 
  System.out.println("\nPlugin ["+ displayName + "] 
   requires" + "\n"); 
  String requires[] = pp.getDependencyList(); 
  if(0 != requires.length ){  
   for(int i=0; i＜requires.length; i++){ 
    System.out.println("\t" + requires[i] ); 
    PluginData pd[] =  
    getPluginDataObjectsFromPluginID(requires[i]); 
    PluginData nextPlugin = null; 
    switch(pd.length){ 
    case 0: 
     //great, we know there is  
     //something missing 
     nextPlugin = null; 
     break; 
    case 1: 
     //best case, everything will be smooth 
     nextPlugin = pd[0]; 
     break; 
    default: 
     //worst case, there must be more  
     //than 1 plugin with the same id 
     //at different locations. 
     String msgLine1 =  
     "Plugin " + displayName +  
     " requires "  +  
     requires[i] + "\n"; 
     String msgLine2 =  
     "Duplicate plug-ins found for ID: \ 
     " " + requires[i] + 
     "\"" +  
     "\n Continuing with higher version... 
     " ; 
     
      //it is bad to give repeated  
      //reminders,  
      //so remind only once per plugin id. 
     if(! alreadyNotified.contains( 
      new String(requires[i]))){ 
     MessageDialog.openInformation(null, 
     "Dependency Walker", 
          msgLine1 +  
       msgLine2); 
     alreadyNotified.add( 
      new String(requires[i])); 
     } 

     //always take the better  
     //version anyway 
     nextPlugin =  
      getBetterVersionPlugin(pd); 
     break; 

    }//end of switch 
    if( null != nextPlugin ){ 
     TreeParent nextinLine =  
     new TreeParent( 
      nextPlugin.getDisplayName(), 
      nextPlugin.isPlugin 
      LoadedInRegistry() 
      ); 
     parentNode.addChild(nextinLine); 
     recursivePluginDependencyWalker( 
      nextPlugin,  
      nextinLine); 
    }else{ 
     TreeParent nextinLine =  
     new TreeParent( 
      requires[i] +  
      " [This plug-in is missing] 
      ", 
      false); 
     parentNode.addChild(nextinLine); 
     //obviously we can't recurse  
     //into a missing plugin... 
    } 
   }//end of for 
  }else{ 
   System.out.println("\t NOTHING:  
   No further dependency \n" ); 
   //no further dependency 
  } 
 } catch (Exception e) { 
  e.printStackTrace(); 
 } 

}