if (!fileNames.containsKey(key)){ fileNames.put(key, fileName);
if (!keys.contains(key)){ keys.add(key); fileNames.add(fileName); setChanged(true);
        public void addFileName(FileName fileName){            MapSetStringKey key = new MapSetStringKey(fileName.getDateiName());            if (!fileNames.containsKey(key)){                fileNames.put(key, fileName);            }            else{                FileName fileNameOld = (FileName)fileNames.get(key);                fileNameOld.setHaeufigkeit(fileName.getHaeufigkeit());            }        }