[Java] FileFilter vprasanje

import java.io.File;
import java.util.Vector;
import javax.swing.filechooser.*;

public class CustomFileFilter extends FileFilter {  
  Vector v;

  public CustomFileFilter() {    
    v=new Vector();
  }

  public void addExtension(String ext) {
    v.add(ext.toLowerCase());
  }

  public boolean accept(File f) {
      if(f != null) {
          if(f.isDirectory()) {
              return true;
          }
          String extension = getExtension(f);
          String ext;
          for (int i=0;i<v.size();i++) {
            ext=(String) v.get(i);
            if(extension != null && extension.equals(ext)) {
              return true;
            }
          }
      }
      return false;
  }

  private String getExtension(File f) {
     if(f != null) {
         String filename = f.getName();
         int i = filename.lastIndexOf('.');
         if(i>0 && i<filename.length()-1) {
             return filename.substring(i+1).toLowerCase();
         };
     }
     return null;
  }

  public String getDescription() {
    String s=new String();
    for (int i=0;i<v.size();i++) {
      s=s.concat(" "+(String) v.get(i));
    }
    return (s.toUpperCase()+" files");
  }  

}

  CustumFileFilter cff=new CustomFileFilter();
  cff.addExtension("jpg");
  //dobimo FileFilter, ki "spusti" cez le *.jpg datoteke