calendar日期类常用操作
package com.ruoyi.receipt.utils;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.*;public class DateUtil {public static void main(String[] args) throws ParseException
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package com.ruoyi.receipt.utils;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;
public class DateUtil {
public static void main(String[] args) throws ParseException {
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
//获取本月的天数
Calendar calendar1 = Calendar.getInstance();
calendar1.set(Calendar.DATE, 1);
calendar1.roll(Calendar.DATE, -1);
System.out.println("本月有:=>"+calendar1.get(Calendar.DATE));
int month1 = calendar1.get(Calendar.MONTH);
int resultMonth1=month1+1;
System.out.println("本月的月份为:=>"+resultMonth1);
//根据年月获取对应的天数
Calendar calendar2 = Calendar.getInstance();
// 指定一个日期
Date date2 = dateFormat.parse("2021-05-31 00:00:00");
calendar2.setTime(date2);
calendar2.set(Calendar.DATE, 1);
calendar2.roll(Calendar.DATE, -1);
System.out.println("指定日期月的天数:=>"+calendar2.get(Calendar.DATE));
//--------------------
Calendar calendar3 = Calendar.getInstance();
// 指定一个日期
Date date3 = dateFormat.parse("2021-05-31 00:00:00");
calendar3.setTime(date3);
//获取年份
System.out.println("获取年份:=>"+calendar3.get(Calendar.YEAR));
int month3 = calendar3.get(Calendar.MONTH);
int resultMonth3=month3+1;
System.out.println("获取月份:=>"+resultMonth3);
//获取当前天数
System.out.println("获取当前天数:=>"+calendar3.get(Calendar.DAY_OF_MONTH));
//获取本月最小天数
System.out.println("获取本月最小天数:=>"+calendar3.getActualMinimum(Calendar.DAY_OF_MONTH));
//获取本月最大天数
System.out.println("获取本月最大天数:=>"+calendar3.getActualMaximum(Calendar.DAY_OF_MONTH));
//获取指定日期是本周几
int week = calendar3.get(Calendar.DAY_OF_WEEK);
int resultWeek=week-1;
System.out.println("获取指定日期是本周几:=>" + resultWeek);
//获取指定日期是当前月的第几天
System.out.println("获取指定日期是当前月的第几天:=>" + calendar3.get(Calendar.DAY_OF_MONTH));
//获取指定日期是当前年的第几天
System.out.println("获取指定日期是当前年的第几天:=>" + calendar3.get(Calendar.DAY_OF_YEAR));
//指定日期+1天
calendar3.add(Calendar.DATE, 1); //增加一天
System.out.println("指定日期+1天:=>"+dateFormat.format(calendar3.getTime()));
//指定日期-2天
calendar3.add(Calendar.DATE, -2); //减小两天
System.out.println("指定日期-2天:=>"+dateFormat.format(calendar3.getTime()));
//格式化日期
System.out.println("格式化日期:=>"+dateFormat.format(calendar3.getTime()));
//将当前日期设置为11号
calendar3.set(Calendar.DATE,11);
System.out.println("将当前日期设置为11号:=>"+dateFormat.format(calendar3.getTime()));
}
}
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