private String getFeature(int wordId, int... fields) { String[] allFeatures = getAllFeaturesArray(wordId); if (allFeatures == null) { return null; } StringBuilder sb = new StringBuilder(); if (fields.length == 0) { // All features for (String feature : allFeatures) { sb.append(CSVUtil.quoteEscape(feature)).append(","); } } else if (fields.length == 1) { // One feature doesn't need to escape value sb.append(allFeatures[fields[0]]).append(","); } else { for (int field : fields) { sb.append(CSVUtil.quoteEscape(allFeatures[field])).append(","); } } return sb.deleteCharAt(sb.length() - 1).toString(); }