1.string格式转化为Date对象

public Date format(String date){
    DateFormat fmt =new SimpleDateFormat("yyyy-MM-dd");
    Date date1=null;
    try {
//String转date
        date1 = fmt.parse(date);
    } catch (ParseException e) {
       // e.printStackTrace();
    }
    return date1;
}

2.Date格式转化为String对象

Date date=new Date();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        String startTime = sdf.format( date.getTime());
        System.out.println(startTime);