import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class HelloWorld {     public static void main(String[] args) {         //指定时间输出格式         SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");         Date dt = new Date();         System.out.println("当前时间：" + sdf.format(dt));         Calendar rightNow = Calendar.getInstance();         rightNow.setTime(dt);                 rightNow.add(Calendar.YEAR,-1);//当时日期减1年         System.out.println("减1年：" + sdf.format(rightNow.getTime()));         rightNow.add(Calendar.MONTH,3);//(在刚才的结果上)再加3个月         System.out.println("再加3个月：" + sdf.format(rightNow.getTime()));         rightNow.add(Calendar.DAY_OF_YEAR,10);//(在刚才的结果上)再加10天                 System.out.println("再加10天：" + sdf.format(rightNow.getTime()));       } }