Hive UDF’S addMonths

our project use hive 0.10 , and in the hiveql , we need use addMonths function builtin in hive-0.11.

so I write this udf and test.

java code:

package myudf;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

import org.apache.hadoop.hive.ql.exec.UDF;

public class addMonths extends UDF {
	final Calendar calendar = Calendar.getInstance();

	// String Year_month int numMonths
	// return date add
	public String evaluate(String _date, int numMonths) throws ParseException {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		addMonth(sdf.parse(_date), numMonths);
		int month = calendar.get(Calendar.MONTH) + 1;
		String strmonth = String.valueOf(month > 9 ? month : "0" + month);
		String strYearMon = calendar.get(Calendar.YEAR) + strmonth;
		return strYearMon;
	}

	Calendar addMonth(Date d, int numMonths) {
		calendar.setTime(d);
		boolean lastDatOfMonth = isLastDayOfMonth(calendar);
		calendar.add(Calendar.MONTH, numMonths);
		if (lastDatOfMonth) {
			int maxDd = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
			calendar.set(Calendar.DAY_OF_MONTH, maxDd);
		}
		return calendar;
	}

	boolean isLastDayOfMonth(Calendar cal) {
		int maxDd = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
		int dd = cal.get(Calendar.DAY_OF_MONTH);
		return dd == maxDd;
	}

}

cd workspace and project folder. then 

jar cvf myudf.jar ./

move to proper folder: mv myudf.jar /home/hadoop/jar/myudf.jar

add jar /home/hadoop/jar/myudf.jar;
create temporary function addMonths as "myudf.addMonths";
select addMonths('2012-03-03',2) as newdate, addMonths('2012-03-03',-2) as newdate2  from nums where num<2;