Java 操作日期，转换字符串格式，指定日期加减天数

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;/*** 日期操作工具类*/
public class DateUtil {private static final String dateFormat = "yyyy-MM-dd";/*** 格式化日期** @param date* @return*/public static String formatDate(Date date) {SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);return sdf.format(date);}/*** 在日期date上增加amount天 。* @param date   处理的日期，非null* @param amount 要加的天数，可能为负数*/public static Date addDays(Date date, int amount) {Calendar now =Calendar.getInstance();now.setTime(date);now.set(Calendar.DATE,now.get(Calendar.DATE)+amount);return now.getTime();}public static void main(String[] args) {System.out.println(DateUtil.formatDate(new Date()));//2020-07-04System.out.println(DateUtil.formatDate(DateUtil.addDays(new Date(), -2)));//2020-07-02}
}