public ExtensionFileFilter(String description,String extension){
  this.description=description;
  this.extensions=new HashSet<String>();
  extensions.add(extension.toLowerCase());
  defaultExtension=extension;
}

public ExtensionFileFilter ( String description , String extension ) { this . description = description ; this . extensions = new HashSet < String > ( ) ; extensions . add ( extension . toLowerCase ( ) ) ; defaultExtension = extension ; }
creates a new instance .
