@Override
            public void addDouble(final double value) {
              double absValue = (value < 0) ? (value * -1) : value;
              int exponent = Math.getExponent(value);
              if ((absValue >= minValue) && (absValue <= maxValue) &&
                  (exponent <= Float.MAX_EXPONENT) && (exponent >= Float.MIN_EXPONENT)) {
                parent.set(index, new FloatWritable((float) value));
              } else {
                parent.set(index, null);
              }
            }
ETypeConverter is an easy way to set the converter for the right type.
ql/src/java/org/apache/hadoop/hive/ql/io/parquet/convert/ETypeConverter.java