private String getOutputWritableType(String primitiveType) throws Exception {
    if (primitiveType.equals("long")) {
      return "LongWritable";
    } else if (primitiveType.equals("double")) {
      return "DoubleWritable";
    } else if (primitiveType.equals("decimal")) {
      return "HiveDecimalWritable";
    } else if (primitiveType.equals("interval_year_month")) {
      return "HiveIntervalYearMonthWritable";
    } else if (primitiveType.equals("interval_day_time")) {
      return "HiveIntervalDayTimeWritable";
    } else if (primitiveType.equals("date")) {
      return "DateWritableV2";
    } else if (primitiveType.equals("timestamp")) {
      return "TimestampWritable";
    }
    throw new Exception("Unimplemented primitive output writable: " + primitiveType);
  }
Return the argument with the first letter capitalized
vector-code-gen/src/org/apache/hadoop/hive/tools/GenVectorCode.java