private String getStringFromBytesColumnVector(BytesColumnVector resultV, int i) {
    String result;
    byte[] resultBytes = Arrays.copyOfRange(resultV.vector[i], resultV.start[i],
        resultV.start[i] + resultV.length[i]);
    result = new String(resultBytes, StandardCharsets.UTF_8);
    return result;
  }
Tests vectorized type cast udfs CastDateToStringWithFormat, CastTimestampToStringWithFormat,
CastStringToDateWithFormat, CastStringToTimestampWithFormat.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/expressions/TestVectorTypeCastsWithFormat.java