SimpleDateFormat yyyy-MM-dd YYYY-MM-dd

import java.util.Calendar; import java.util.Date; import java.text.SimpleDateFormat; public class DateTest { public static void main(String[] args) { // 跨年边缘的时间 Calendar calendar = Calendar.getInstance(); calendar.set(2025, Calendar.DECEMBER, 31); Date date = calendar.getTime(); SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd");// 正确写法- 小写 yyyy SimpleDateFormat sdf2 = new SimpleDateFormat("YYYY-MM-dd");// 错误写法- 大写 YYYY System.out.println("yyyy: " + sdf1.format(date)); System.out.println("YYYY: " + sdf2.format(date)); } }