[Java] Java Calendar类使用总结及使用实例

public abstract class calendar implements serializable, cloneable, comparable<calendar>

public static calendar getinstance()
{
 return createcalendar(timezone.getdefault(), locale.getdefault(locale.category.format));
}

calendar calendar = calendar.getinstance();

package com.zwwhnly.springbootdemo;
 
import java.util.calendar;
 
public class calendardemo {
 public static void main(string[] args) {
 calendar calendar = calendar.getinstance();
 
 int year = calendar.get(calendar.year);
 // 月份的下标是从0开始的，即0~11分别代表1~12月，因此需要+1
 int month = calendar.get(calendar.month) + 1;
 int day = calendar.get(calendar.day_of_month);
 int hour = calendar.get(calendar.hour_of_day); // 24小时制
 int minute = calendar.get(calendar.minute);
 int second = calendar.get(calendar.second);
 
 system.out.println("现在是：" + year + "年" + month + "月" + day + "日" + hour + "时" + minute + "分" + second + "秒");
 }
}

现在是：2019年2月21日15时36分38秒

calendar calendar = calendar.getinstance();
calendar.set(2019, calendar.february, 21, 23, 59, 59);
 
system.out.println(calendar.gettime());

calendar calendar = calendar.getinstance();
calendar.set(calendar.year, 2019);
calendar.set(calendar.month, calendar.february);
calendar.set(calendar.day_of_month, 21);
calendar.set(calendar.hour_of_day, 23);
calendar.set(calendar.minute, 59);
calendar.set(calendar.second, 59);
 
system.out.println(calendar.gettime());

thu feb 21 23:59:59 cst 2019

public static void main(string[] args) {
 calendar calendar = calendar.getinstance();
 calendar.set(2019, calendar.february, 21, 23, 59, 59);
 calendar.add(calendar.second, 1);
 system.out.println(calendar.gettime());
}

fri feb 22 00:00:00 cst 2019

calendar calendar = calendar.getinstance();
 
calendar.set(2019, calendar.january, 31);
system.out.println(calendar.gettime());
calendar.add(calendar.month, 1);
system.out.println(calendar.gettime());
calendar.add(calendar.month, 2);
system.out.println(calendar.gettime());

thu jan 31 15:58:03 cst 2019
thu feb 28 15:58:03 cst 2019
sun apr 28 15:58:03 cst 2019

package com.zwwhnly.springbootdemo;
 
import java.text.simpledateformat;
import java.util.calendar;
 
public class calendardemo {
 public static void main(string[] args) {
 system.out.println(getfirstdayofmonth(2019, 2));
 system.out.println(getlastdayofmonth(2019, 2));
 
 system.out.println(getfirstdayofmonth(2019, 3));
 system.out.println(getlastdayofmonth(2019, 3));
 }
 
 public static string getlastdayofmonth(int year, int month) {
 calendar calendar = calendar.getinstance();
 calendar.set(calendar.year, year);
 calendar.set(calendar.month, month - 1);
 calendar.set(calendar.day_of_month, calendar.getactualmaximum(calendar.date));
 
 return new simpledateformat("yyyy-mm-dd").format(calendar.gettime());
 }
 
 public static string getfirstdayofmonth(int year, int month) {
 calendar calendar = calendar.getinstance();
 calendar.set(calendar.year, year);
 calendar.set(calendar.month, month - 1);
 calendar.set(calendar.day_of_month, calendar.getminimum(calendar.date));
 
 return new simpledateformat("yyyy-mm-dd").format(calendar.gettime());
 }
}

2019-02-01
2019-02-28
2019-03-01
2019-03-31