// Check if file exist on ResultCollector listener before start the test

  		SearchByClass<ResultCollector> resultListeners = new SearchByClass<ResultCollector>(ResultCollector.class); 

        tree.traverse(resultListeners);

        Iterator<ResultCollector> irc = resultListeners.getSearchResults().iterator();

        while (irc.hasNext() ) { 

        	ResultCollector rc = irc.next();

        	File f = new File(rc.getFilename());

        	if (f.exists())

        	{

        		  int response = JOptionPane.showConfirmDialog(null, 

                          "Le fichier \"" + rc.getFilename() + "\" existe, voulez-vous continuer?", // $NON-NLS-1$

                          "Warning", // $NON-NLS-1$

                          JOptionPane.YES_NO_OPTION);

        		  if ( response == JOptionPane.NO_OPTION )

        		  {

        			  stop();

        			  return;

        		  }

        	}

        }

import java.io.File;

import javax.swing.JOptionPane;

import org.apache.commons.io.FileUtils;

import org.apache.jmeter.gui.GuiPackage;

import org.apache.jmeter.reporters.ResultCollector;

        SearchByClass<ResultCollector> resultListeners = new SearchByClass<ResultCollector>(ResultCollector.class); 

        test.traverse(resultListeners);

        Iterator<ResultCollector> irc = resultListeners.getSearchResults().iterator();

        while (irc.hasNext() ) { 

        	ResultCollector rc = irc.next();

        	File f = new File(rc.getFilename());

        	if (f.exists())

        	{

        		  int response = JOptionPane.showConfirmDialog(null, 

                          "Le fichier \"" + rc.getFilename() + "\" existe, voulez-vous continuer?", // $NON-NLS-1$

                          "Warning", // $NON-NLS-1$

                          JOptionPane.YES_NO_OPTION);

        		  if ( response == JOptionPane.NO_OPTION )

        		  {

        			  return;

        		  }

        	}

        }