public void init(BytesRefArrayWritable cols) {
    for (int i = 0; i < prjColIDs.length; ++i) {
      int fieldIndex = prjColIDs[i];
      if (fieldIndex < cols.size()) {
        fieldInfoList[fieldIndex].init(cols.unCheckedGet(fieldIndex));
      } else {
        // select columns that actually do not exist in the file.
        fieldInfoList[fieldIndex].init(null);
      }
    }
  }
create the lazy object for this field

@param objectInspector
         the object inspector for the field
@return the lazy object for the field
serde/src/java/org/apache/hadoop/hive/serde2/columnar/ColumnarStructBase.java