public String toString() { if (isEmpty()) return DEPReader.BLANK_COLUMN; StringBuilder build = new StringBuilder(); List<String> keys = new ArrayList<String>(keySet()); Collections.sort(keys); for (String key : keys) { build.append(DELIM_FEATS); build.append(key); build.append(DELIM_KEY_VALUE); build.append(get(key)); } return build.toString().substring(DELIM_FEATS.length()); } }