例如,我有日期:“23/2/2010”(2010年2月23日)。我想把它传递给一个返回星期几的函数。我该怎么做呢?

在这个例子中,函数应该返回String "Tue"。

此外,如果只需要日期顺序,如何检索?


当前回答

这是正确的…

java.time.LocalDate; //package related to time and date

它提供了内置方法getDayOfWeek()来获取特定星期的日期:

int t;
Scanner s = new Scanner(System.in);
t = s.nextInt();
s.nextLine();
 while(t-->0) { 
    int d, m, y;
    String ss = s.nextLine();
    String []sss = ss.split(" ");
    d=Integer.parseInt(sss[0]);
    m = Integer.parseInt(sss[1]);
    y = Integer.parseInt(sss[2]);

    LocalDate l = LocalDate.of(y, m, d); //method to get the localdate instance
    System.out.println(l.getDayOfWeek()); //this returns the enum DayOfWeek

要将枚举l.getDayOfWeek()的值赋给一个字符串,您可能会使用enum中名为name()的方法,该方法返回enum对象的值。

其他回答

对于Java 8或更高版本,Localdate更可取

import java.time.LocalDate;

public static String findDay(int month, int day, int year) {

    LocalDate localDate = LocalDate.of(year, month, day);

    java.time.DayOfWeek dayOfWeek = localDate.getDayOfWeek();
    System.out.println(dayOfWeek);

    return dayOfWeek.toString();
}

注意:如果输入是字符串/用户定义的,那么你应该把它解析成int。

public class TryDateFormats {
    public static void main(String[] args) throws ParseException {
        String month = "08";
        String day = "05";
        String year = "2015";
        String inputDateStr = String.format("%s/%s/%s", day, month, year);
        Date inputDate = new SimpleDateFormat("dd/MM/yyyy").parse(inputDateStr);
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(inputDate);
        String dayOfWeek = calendar.getDisplayName(Calendar.DAY_OF_WEEK, Calendar.LONG, Locale.US).toUpperCase();
        System.out.println(dayOfWeek);
    }
}

可以使用以下代码片段进行输入,如(day = "08", month = "05", year = "2015",输出将是"WEDNESDAY")

Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.DAY_OF_MONTH, Integer.parseInt(day));
calendar.set(Calendar.MONTH, (Integer.parseInt(month)-1));
calendar.set(Calendar.YEAR, Integer.parseInt(year));
String dayOfWeek = calendar.getDisplayName(Calendar.DAY_OF_WEEK, Calendar.LONG, Locale.US).toUpperCase();

是的。根据具体情况:

You can use java.util.Calendar: Calendar c = Calendar.getInstance(); c.setTime(yourDate); int dayOfWeek = c.get(Calendar.DAY_OF_WEEK); if you need the output to be Tue rather than 3 (Days of week are indexed starting at 1 for Sunday, see Calendar.SUNDAY), instead of going through a calendar, just reformat the string: new SimpleDateFormat("EE").format(date) (EE meaning "day of week, short version") if you have your input as string, rather than Date, you should use SimpleDateFormat to parse it: new SimpleDateFormat("dd/M/yyyy").parse(dateString) you can use joda-time's DateTime and call dateTime.dayOfWeek() and/or DateTimeFormat. edit: since Java 8 you can now use java.time package instead of joda-time

通过使用java.util.scanner包给用户输入日期、月和年来查找星期几的程序:

import java.util.Scanner;

public class Calender {
    public static String getDay(String day, String month, String year) {

        int ym, yp, d, ay, a = 0;
        int by = 20;
        int[] y = new int[]{6, 4, 2, 0};
        int[] m = new int []{0, 3, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5};

        String[] wd = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

        int gd = Integer.parseInt(day);
        int gm = Integer.parseInt(month);
        int gy = Integer.parseInt(year);

        ym = gy % 100;
        yp = ym / 4;
        ay = gy / 100;

        while (ay != by) {
            by = by + 1;
            a = a + 1;

            if(a == 4) {
                a = 0;
            }
        }

        if ((ym % 4 == 0) && (gm == 2)) {
            d = (gd + m[gm - 1] + ym + yp + y[a] - 1) % 7;
        } else
            d = (gd + m[gm - 1] + ym + yp + y[a]) % 7;

        return wd[d];
    }

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        String day = in.next();
        String month = in.next();
        String year = in.next();

        System.out.println(getDay(day, month, year));
    }
}