第六章第三十三题（当前日期和时间）(Current date and time)

**6.33（当前日期和时间）调用System.currentTimeMillis()返回从1970年1月1日0点开始至今为止的毫秒数。编写程序，显示当前日期和时间。 下面是运行示例： Current date and time is May 16, 2012 10:34:23 **6.33(Current date and time) Invoking System.currentTimeMillis() returns the elapsed time in milliseconds since midnight of January 1, 1970. Write a program that displays the date and time. Here is a sample run: Current date and time is May 16, 2012 10:34:23参考代码： package chapter06; public class Code_33 { public static void main(String[] args) { long totalMilliseconds = System.currentTimeMillis(); int totalDays = (int) (totalMilliseconds / 1000 / 60 / 60 / 24); long totalSeconds = totalMilliseconds / 1000; long currentSecond = totalSeconds % 60; long totalMinutes = totalSeconds / 60; long currentMinute = totalMinutes % 60; long totalHours = totalMinutes / 60; long currentHour = totalHours % 24; int currentYears = 1970, currentMonths = 1, currentDays; while (totalDays >= 365) { if (isLeapYear(currentYears)) totalDays -= 366; else totalDays -= 365; currentYears++; } while (totalDays >= 28) { if (currentMonths == 1 || currentMonths == 3 || currentMonths == 5 || currentMonths == 7 || currentMonths == 8 || currentMonths == 10 || currentMonths == 12) { totalDays -= 31; currentMonths++; } else if (currentMonths == 4 || currentMonths == 6 || currentMonths == 9 || currentMonths == 11) { totalDays -= 30; currentMonths++; } else if (isLeapYear(currentYears) && currentMonths == 2) { totalDays -= 29; currentMonths++; } else { totalDays -= 28; currentMonths++; } } if (totalDays == 0) currentDays = 1; else currentDays = totalDays + 1; // Display results System.out.printf("Current date and time is %s %d, %d %d:%d:%d", MonthEnglish(currentMonths), currentDays, currentYears, currentHour, currentMinute, currentSecond); } public static boolean isLeapYear(int year) { return (year % 400 == 0 || (year % 100 != 0 && year % 4 == 0)); } public static String MonthEnglish(int month) { String monthString; switch(month) { case 1: monthString = "January"; break; case 2: monthString = "February"; break; case 3: monthString = "March"; break; case 4: monthString = "April"; break; case 5: monthString = "May"; break; case 6: monthString = "June"; break; case 7: monthString = "July"; break; case 8: monthString = "August"; break; case 9: monthString = "September"; break; case 10: monthString = "October"; break; case 11: monthString = "November"; break; case 12: monthString = "December"; break; default: monthString = ""; } return monthString; } } 结果显示： Current date and time is October 21, 2020 15:10:33 Process finished with exit code 0