java 年月和年周转化为年月日的转换

package com.sophon.szc.service.util;

没错我喜欢直接上代码： 
两个方法传入格式分别是： 

MONTH 2018-08    WEEK 2018-33
MONTH 201808     WEEK 201833
import com.sophon.szc.service.struct.enums.TimeGranularity;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.Date;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.List;

public class DateHelper {
    private static Logger logger = LoggerFactory.getLogger(DateHelper.class);

    public static String changeDate(String timeType ,String timeValue){
        String dateString =null;
        String[] arr = timeValue.split("-");
        //根据传入参数和格式转换为日期
        Date date;
        if (timeType.equals(TimeGranularity.MONTH.toString())){
            date = Date.valueOf(String.format("%s-%s-%s", arr[0], arr[1], 1));
            dateString = date.toString();
        }else if (timeType.equals(TimeGranularity.WEEK.toString())) {
            Calendar cal = Calendar.getInstance();
            cal.setFirstDayOfWeek(Calendar.MONDAY);
            cal.set(Calendar.YEAR, Integer.valueOf(arr[0]));
            cal.set(Calendar.WEEK_OF_YEAR, Integer.valueOf(arr[1]));
            cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
            date = Date.valueOf(new SimpleDateFormat("yyyy-MM-dd").format(cal.getTime()));
            dateString =date.toString();
        }
       return dateString;
    }

    public static String transtlateDate(String timeType ,String timeValue){
        String dateString =null;
        StringBuilder dateToStringBuilder = new StringBuilder(timeValue);
        dateToStringBuilder.insert(4,"-");
        String dateToString = new String (dateToStringBuilder);
        String[] arr = dateToString.split("-");
        //根据传入参数和格式转换为日期
        Date date;
        if (timeType.equals(TimeGranularity.MONTH.toString())){
            date = Date.valueOf(String.format("%s-%s-%s", arr[0], arr[1], 1));
            dateString = date.toString();
        }else if (timeType.equals(TimeGranularity.WEEK.toString())) {
            Calendar cal = Calendar.getInstance();
            cal.setFirstDayOfWeek(Calendar.MONDAY);
            cal.set(Calendar.YEAR, Integer.valueOf(arr[0]));
            cal.set(Calendar.WEEK_OF_YEAR, Integer.valueOf(arr[1]));
            cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
            date = Date.valueOf(new SimpleDateFormat("yyyy-MM-dd").format(cal.getTime()));
            dateString =date.toString();
        }
        return dateString;
    }
}