我已经编写了下面的pig udf来测试chararray列是否具有有效的'yyyy-mm-dd'日期格式。但是当使用下面的脚本进行测试时，我得到了下面的错误。数据是否有问题，因为我处理空元组是为了考虑数据中的空值以及不存在的值。另外，我应该删除数据文件中的空行吗？

Caused by: org.apache.pig.backend.executionengine.ExecException: ERROR 2114: Expected input to be chararray, but got NULL
        at IsValidDateTime.exec(IsValidDateTime.java:41)
        at IsValidDateTime.exec(IsValidDateTime.java:18)

日期.txt

2019-12-27,2020-08-20
2017-05-09,2018-10-04
2016-09-25,2020-01-19
,2020-08-20
NULL,2017-09-28
2016-11-15,NULL
2018-04-17,Thu Aug-20 2020
2017-05-09,2020-08-20
Mon Jan-20 2020,2020-08-20
<empty line>
------------------------------------------

有效日期（应为所有有效的“yyyy-mm-dd”开始日期和结束日期）

2019-12-27,2020-08-20
2017-05-09,2018-10-04
2016-09-25,2020-01-19
2017-05-09,2020-08-20

Pig手稿

REGISTER 'IsValidDateTime.jar'

DEFINE IsValidDateTime IsValidDateTime();

dates = LOAD 'dates.txt' USING PigStorage(',') AS (start_dt:chararray, end_dt:chararray);
DUMP dates;
dates_valid = FILTER dates BY (IsValidDateTime(start_dt) AND IsValidDateTime(end_dt));
DUMP dates_valid;

isvaliddatetime筛选器自定义项

import org.apache.pig.FilterFunc;
import org.apache.pig.PigException;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.data.DataType;
import org.apache.pig.data.Tuple;

import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
public class IsValidDateTime extends FilterFunc {
    private static String datePattern = "yyyy-MM-dd";
    public Boolean exec(Tuple input) throws IOException {
        if (input == null || input.size() == 0)
            return false;
        try {
            Object date = input.get(0);
            if(DataType.findType(date) == DataType.CHARARRAY){
                String dateStr = String.valueOf(date);
                if(dateStr != null && dateStr.length() != 0) {
                    try {
                        SimpleDateFormat format = new SimpleDateFormat(datePattern);
                        format.setLenient(false);
                        format.parse(dateStr);
                    } catch (ParseException | IllegalArgumentException e) {
                        return false; //date string does not match 'yyyy-MM-dd' format
                    }
                    return true; //date string is of valid format 'yyyy-MM-dd'
                }
                return false; //empty or null date string
            } else {
                int errCode = 2114;
                String msg = "Expected input to be chararray, but got " +  DataType.findTypeName(date) ;
                throw new ExecException(msg, errCode, PigException.BUG);
            }
        } catch(ExecException ee) {
            throw ee;
        }
    }
}