DateProcessor.java

package io.konik.csv.processor;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.util.CsvContext;

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

/**
 * Custom {@link CellProcessor} for {@link Date} class.
 *
 * It uses proper {@link java.text.DateFormat} to convert object from and to a String value.
 */
public final class DateProcessor implements CellProcessor {

	private static final Logger log = LoggerFactory.getLogger(DateProcessor.class);

	private static final ThreadLocal<DateFormat> dateFormat = new ThreadLocal<DateFormat>() {
		@Override
		protected DateFormat initialValue() {
			return new SimpleDateFormat("yyyyMMdd");
		}
	};

	public DateFormat getDateFormat() {
		return dateFormat.get();
	}

	@Override
	public Object execute(Object value, CsvContext context) {

		if (value instanceof String) {
			String dateStr = (String) value;
			Date date = null;

			try {
				return dateFormat.get().parse(dateStr);
			} catch (ParseException e) {
				log.error("Parsing {} throws an exception: {}", value, e.getMessage());
				throw new RuntimeException(String.format("Value %s does not match valid date format (yyyyMMdd)", value));
			}
		}

		if (value instanceof Date) {
			return dateFormat.get().format(value);
		}

		return null;
	}
}