查找上个月的最后一个星期五并检查当前日期之间的天数

Question

我需要找到上个月的最后一个星期五。这个月是六月。我需要五月的最后一个星期五。在这种情况下（5 月 29 日）。我只能找到当月的最后一个星期五。找到上个月的星期五后，我需要检查从多少天开始。如果距离上周五已经 5 天，则执行任务。希望这是清楚的。如果没有，请询问，我可以更详细地解释。

public class task {

static String lastFriday;
static String dtToday;

public static void main(String[] args) {
   //daysInBetween = current day - (last month's friday date)

   if (daysInBetween = 5) {
      //run program after 5 days
   } else { //quit program }
}

// Gets last Friday of the Month
// Need last Friday of previous Month...
public static String getLastFriday() {
    Calendar cal = new GregorianCalendar();
    cal.set(GregorianCalendar.DAY_OF_WEEK, Calendar.FRIDAY);
    cal.set(GregorianCalendar.DAY_OF_WEEK_IN_MONTH, -1);        
    SimpleDateFormat date_format = new SimpleDateFormat("yyyy/MM/dd");
    lastFriday = date_format.format(cal.getTime()); 
    return lastFriday;
}

// Gets today's date
public static String getToday() {
    Calendar cal = new GregorianCalendar();     
    SimpleDateFormat date_format = new SimpleDateFormat("yyyy/MM/dd");      
    dtToday = date_format.format(cal.getTime());    
    return dtToday;
}
}

Answer 1

使用方法找到 last Friday of any month -

public Date getLastFriday( int month, int year ) {
   Calendar cal = Calendar.getInstance();
   cal.set( year, month + 1, 1 );
   cal.add( Calendar.DAY_OF_MONTH, -( cal.get( Calendar.DAY_OF_WEEK ) % 7 + 1 ) );
   return cal.getTime();
}

您可以使用以下方法找出 2 天之间的差异 -

public int getDifferenceDays(Date d1, Date d2) {
   int daysdiff=0;

   long diff = d2.getTime() - d1.getTime();
   long diffDays = diff / (24 * 60 * 60 * 1000)+1;
   daysdiff = (int) diffDays;

   return daysdiff;
 }

Answer 2

您快到了，只需将以下行添加到您的 getLastFriday 方法中：

// Gets last Friday of the Month
// Need last Friday of previous Month...
public static String getLastFriday() {
    Calendar cal = new GregorianCalendar();
    // reduce the "current" month by 1 to get the "previous" month
    cal.set(GregorianCalendar.MONTH, cal.get(GregorianCalendar.MONTH) - 1); 
    cal.set(GregorianCalendar.DAY_OF_WEEK, Calendar.FRIDAY);
    cal.set(GregorianCalendar.DAY_OF_WEEK_IN_MONTH, -1);        
    SimpleDateFormat date_format = new SimpleDateFormat("yyyy/MM/dd");
    lastFriday = date_format.format(cal.getTime()); 
    return lastFriday;
}

然后您可以阅读其中一个问题及其答案以计算天数：Finding days difference in java or Calculating the difference between two Java date instances。

查找上个月的最后一个星期五并检查当前日期之间的天数

Find the last Friday of previous month and check how many days in between current date

java

calendar

date