code: public static List<Writable> rowToWritables(Schema schema, Row row) {
          List<Writable> ret = new ArrayList<>();
          for (int i = 0; i < row.size(); i++) {
              switch (schema.getType(i)) {
                  case Double:
                      ret.add(new DoubleWritable(row.getDouble(i)));
                      break;
                  case Float:
                      ret.add(new FloatWritable(row.getFloat(i)));
                      break;
                  case Integer:
                      ret.add(new IntWritable(row.getInt(i)));
                      break;
                  case Long:
                      ret.add(new LongWritable(row.getLong(i)));
                      break;
                  case String:
                      ret.add(new Text(row.getString(i)));
                      break;
                  default:
                      throw new IllegalStateException("Illegal type");
              }
          }
          return ret;
      }
docs: Convert a given Row to a list of writables, given the specified Schema
  
  @param schema Schema for the data
  @param row    Row of data