Finding the Java Date of the next Monday 6:00, for example -
i trying create code in java can determine date of next recurring time of week specified. hard explain i'll give example. march 1st (a thursday) , user wants know when next saturday 5:00 code should output march 3rd, 5:00 date variable , if march 4th, program should output march 10th , on...
the user however, can specify time of week want. done long value offsets time of week thursday 0:00 in milliseconds. i'm having trouble wrapping head around got far:
public static long findnexttimeoftheweek(long offset) { return system.currenttimemillis() - ((system.currenttimemillis() - offset) % 604800000) + 604800000; } if help, appreciated. , if more clarification needed, ask. p.s. 604800000 number of milliseconds in week.
i suggest use calendar class, can manipulate , date object using calendar#gettime. see example below, want:
import java.util.calendar; import java.util.locale; import java.util.scanner; public class main { public static int dayofweekiwant(final string dayofweekiwantstring) throws exception { final int dayofweekiwant; if ("sunday".equalsignorecase(dayofweekiwantstring)) { dayofweekiwant = calendar.sunday; } else if ("monday".equalsignorecase(dayofweekiwantstring)) { dayofweekiwant = calendar.monday; } else if ("tuesday".equalsignorecase(dayofweekiwantstring)) { dayofweekiwant = calendar.tuesday; } else if ("wednesday".equalsignorecase(dayofweekiwantstring)) { dayofweekiwant = calendar.wednesday; } else if ("thursday".equalsignorecase(dayofweekiwantstring)) { dayofweekiwant = calendar.thursday; } else if ("friday".equalsignorecase(dayofweekiwantstring)) { dayofweekiwant = calendar.friday; } else if ("saturday".equalsignorecase(dayofweekiwantstring)) { dayofweekiwant = calendar.saturday; } else { throw new exception( "invalid input, must \"day_of_week hour\""); } return dayofweekiwant; } public static string getordinal(int cardinal) { string ordinal = string.valueof(cardinal); switch ((cardinal % 10)) { case 1: ordinal += "st"; break; case 2: ordinal += "nd"; break; case 3: ordinal += "rd"; break; default: ordinal += "th"; } return ordinal; } public static void printdate(calendar calendar) { string dayofweek = calendar.getdisplayname(calendar.day_of_week, calendar.long, locale.english); string dayofmonth = getordinal(calendar.get(calendar.day_of_month)); int hour = calendar.get(calendar.hour_of_day); int minute = calendar.get(calendar.minute); system.out.printf("%s %s %02d:%02d", dayofweek, dayofmonth, hour, minute); } public static void main(string[] args) { calendar calendar = calendar.getinstance(); scanner scanner = new scanner(system.in); final int today = calendar.get(calendar.day_of_week); system.out.println("please, input day of week want know:"); boolean inputok = false; while (!inputok) try { string input = scanner.nextline(); string[] split = input.split("\\s"); string dayofweekiwantstring = split[0]; string[] splithour = split[1].split(":"); int hour = integer.parseint(splithour[0]); int minute = integer.parseint(splithour[1]); int dayofweekiwant = dayofweekiwant(dayofweekiwantstring); int diff = (today >= dayofweekiwant) ? (7 - (today - dayofweekiwant)) : (dayofweekiwant - today); calendar.add(calendar.day_of_week, diff); calendar.set(calendar.hour_of_day, hour); calendar.set(calendar.minute, minute); calendar.set(calendar.second, 0); calendar.set(calendar.millisecond, 0); inputok = true; } catch (exception e) { // using generic exception explanation purpose // must create specific exception system.out .println("invalid input, must enter valid input in format: \"day_of_week hour\""); continue; } printdate(calendar); } } more information:
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