解决 java.text.ParseException: Unparseable date

java.text.ParseException: Unparseable date: "2023-03-07"
  at java.text.DateFormat.parse(DateFormat.java:366)
  at com.hidata.hidbm.Test11.getWeeksInMonthOfDate(Test11.java:27)
  at com.hidata.hidbm.Test11.main(Test11.java:14)
2023年3月第2周
Process finished with exit code 0

SimpleDateFormat df=new SimpleDateFormat();

SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");

package com.hidata.hidbm;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
/**
 * @Description :
 * @Date: 2023-03-07 10:05
 */
public class Demo{
    public static void main(String[] args) {
        System.out.println(getWeeks("2023-03-07"));
    }
    /**
     * 获取指定日期-XXXX年X月第X周
     */
    public static String getWeeks(String dateStr){
        SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");
        Calendar calendar = Calendar.getInstance();
        try {
            calendar.setTime(df.parse(dateStr));
        } catch (ParseException e) {
            e.printStackTrace();
        }
        //设置每周第一天为周一 默认每周第一天为周日
        calendar.setFirstDayOfWeek(Calendar.MONDAY);
        //获取当前日期所在周周日
        calendar.set(Calendar.DAY_OF_WEEK,Calendar.SUNDAY);
        return String.valueOf(calendar.get(Calendar.YEAR)).concat("年").
                concat(String.valueOf(calendar.get(Calendar.MONTH)+1)).concat("月第").
                concat(String.valueOf(calendar.get(Calendar.WEEK_OF_MONTH))).concat("周");
    }
}