java calendar赋值_Java常用日期操作
//日期轉字符串,根據需要調整格式
@Testpublic voidDateToString(){
Date currentTime= newDate();
SimpleDateFormat formatter= new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateString=formatter.format(currentTime);
System.out.println(dateString);
}字符串轉日期
void StrToDate() throwsParseException {
String dateStr= "2019-01-19";
SimpleDateFormat format= new SimpleDateFormat("yyyy-MM-dd");
Date date= null;
date=format.parse(dateStr);
System.out.println(date);
}獲取本月第一天
void getMonthFirstDay() ParseException {
SimpleDateFormat format= );
Calendar cal=Calendar.getInstance();獲取當前日期
cal.set(Calendar.DAY_OF_MONTH,1);設置為1號,當前日期既為本月第一天
String monthFirstDay =format.format(cal.getTime());
System.out.println(monthFirstDay);
}獲取本月最后一天
void getMonthLastDay() 獲取當前日期
cal.set(Calendar.DAY_OF_MONTH,cal.getActualMaximum(Calendar.DAY_OF_MONTH));
String monthLastDay=format.format(cal.getTime());
System.out.println(monthLastDay);
}獲取上個月第一天。最后一天同理
void getLastMonthFirstDay() 獲取當前日期
cal.add(Calendar.MONTH,-1);
cal.set(Calendar.DAY_OF_MONTH,1);通過Calendar獲取年月日時分秒
void testCalendar() ParseException {
Calendar cal=Calendar.getInstance();賦值時年月日時分秒常用的6個值，注意月份下標從0開始，所以取月份要+1
System.out.println("年:" +cal.get(Calendar.YEAR));
System.out.println("月:" + (cal.get(Calendar.MONTH) + 1));
System.out.println("日:" +cal.get(Calendar.DAY_OF_MONTH));
System.out.println("時:" +cal.get(Calendar.HOUR_OF_DAY));
System.out.println("分:" +cal.get(Calendar.MINUTE));
System.out.println("秒:" +cal.get(Calendar.SECOND));
}得到兩個時間相隔的天數
void getBetweenDay() ParseException{
String dateStr1= "2019-01-01";
String dateStr2= "2019-01-19";
SimpleDateFormat format= );
Date date1=format.parse(dateStr1);
Date date2=format.parse(dateStr2);
Long inteverDay= (date2.getTime()-date1.getTime())/(1000*60*60*24);
System.out.println(inteverDay);
}當前日期加一天
void addCurrentDay() ParseException {
String datess= "2019-02-28");
Date parse=format.parse(datess);
Calendar cal=Calendar.getInstance();cal.setTime(parse);
cal.add(Calendar.DAY_OF_YEAR,+1);
String monthFirstDay=Calendar轉換成date
void CalToDate() ParseException {
Calendar cal=Calendar.getInstance();
Date date=cal.getTime();
}date轉換成Calendar
void DateToCal() Calendar.getInstance();
Date date= Date();
cal.setTime(date);
}獲得當前周周一的日期
getMonday(){
Date date= Date();
Calendar c=Calendar.getInstance();
c.setTime(date);monday可以替換成任意星期幾
c.set(Calendar.DAY_OF_WEEK,Calendar.MONDAY);
String dateStr= ).format(c.getTime());
System.out.println(dateStr);
}判斷兩個時間是否在同一周
booleanisSameWeekDates(Date date1,Date date2) {
Calendar cal1=Calendar.getInstance();
Calendar cal2=Calendar.getInstance();
cal1.setTime(date1);
cal2.setTime(date2);int subYear = cal1.get(Calendar.YEAR) -cal2.get(Calendar.YEAR);if (0 ==subYear) {if (cal1.get(Calendar.WEEK_OF_YEAR) ==cal2.get(Calendar.WEEK_OF_YEAR)){return true;
}
}else if (1 == subYear && 11 ==cal2.get(Calendar.MONTH)) {如果12月的最后一周橫跨來年第一周的話則最后一周即算做來年的第一周
if (-1 == subYear && 11 ==cal1.get(Calendar.MONTH)) {;
}
}false;
}
總結
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