java - 使用 Java GregorianCalendar 类打印正确的日期

Question

我正在尝试打印一些东西，例如今天的日期、星期几、从现在起 100 天后的日期、从现在起一百天后的星期几、我的生日和星期几一周的一周，以及我生日后的 10,000 天和一周的那一天。现在，我知道 GregorianCalendar 从一月份的 0 开始到十二月份的 11。我明白了，所以当我尝试打印日期时它说今天的日期是 2012 年 8 月 25 日而不是 2012 年 9 月 25 日是有道理的，但我不知道如何在不提前额外设置日期的情况下更正此问题月，然后实际上将月份放入十月而不是九月。

这是我目前正在处理的事情。

        GregorianCalendar cal = new GregorianCalendar();
        int dayOfMonth = cal.get(Calendar.DAY_OF_MONTH);
        int month = cal.get(Calendar.MONTH);
        int year = cal.get(Calendar.YEAR);
        int weekday = cal.get(Calendar.DAY_OF_WEEK);
        cal.add(Calendar.DAY_OF_MONTH, 100);
        int dayOfMonth2 = cal.get(Calendar.DAY_OF_MONTH);
        int month2 = cal.get(Calendar.MONTH);
        int year2 = cal.get(Calendar.YEAR);
        int weekday2 = cal.get(Calendar.DAY_OF_WEEK);
        GregorianCalendar birthday = new GregorianCalendar(1994, Calendar.JANUARY, 1);
        int dayOfMonth3 = birthday.get(Calendar.DAY_OF_MONTH);
        int month3 = birthday.get(Calendar.MONTH);
        int year3 = birthday.get(Calendar.YEAR);
        int weekday3 = birthday.get(Calendar.DAY_OF_WEEK);
        birthday.add(Calendar.DAY_OF_MONTH, 10000);
        int weekday4 = birthday.get(Calendar.DAY_OF_WEEK);
        int dayOfMonth4 = birthday.get(Calendar.DAY_OF_MONTH);
        int month4 = birthday.get(Calendar.MONTH);
        int year4 = birthday.get(Calendar.YEAR);
        System.out.printf("Todays date is " +month + "/" +dayOfMonth +"/" +year +".");
        System.out.printf(" It is day " +weekday +" of the week");
        System.out.println("");
        System.out.printf("In 100 days it will be " +month2 + "/" +dayOfMonth2 +"/" +year2 +". ");
        System.out.printf("Day " +weekday2 +" of the week");
        System.out.println("");
        System.out.printf("My Birthday is " +month3 + "/" +dayOfMonth3 +"/" +year3 +". "+"Day " +weekday3 +" of the week");
        System.out.println("");
        System.out.printf("10,000 days after my birthday is " +month4 + "/" +dayOfMonth4 +"/" +year4 +". " +"Day " +weekday4 +" of the week");

所以我需要帮助来更正今天日期、100 天后的日期、我的生日日期以及我生日后的 10,000 天的月份。非常感谢任何帮助或见解。

Answer 1

I get that, so it makes sense that when I attempt to print the date it says today's date is 8/25/12 rather than 9/25/12, but I have no idea how to correct this without setting the date ahead an extra month

如果你要通过做打印月份

int month = cal.get(Calendar.MONTH);
...
 System.out.printf("Todays date is " + month + ...

然后你想打印 month + 1，而不仅仅是 month。

尽管您最终会通过使用 SimpleDateFormat 来节省更多的时间和麻烦。用于将日期格式化为字符串。