private String getDay(Date date){

    SimpleDateFormat simpleDateFormat = new SimpleDateFormat("EEEE");
    //System.out.println("DAY "+simpleDateFormat.format(date).toUpperCase());                       
    return simpleDateFormat.format(date).toUpperCase();
}

private String getDay(String dateStr){
    //dateStr must be in DD-MM-YYYY Formate
    Date date = null;
    String day=null;

    try {
        date = new SimpleDateFormat("DD-MM-YYYY").parse(dateStr);

        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("EEEE");
        //System.out.println("DAY "+simpleDateFormat.format(date).toUpperCase());
        day = simpleDateFormat.format(date).toUpperCase();


    } catch (ParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }


    return day;
}

Calendar cal = Calendar.getInstance(desired date);
cal.setTimeInMillis(System.currentTimeMillis());
int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK);

通过提供当前时间戳获取日值。

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));
    }
}

...
import java.time.LocalDate;
...
//String month = in.next();
int mm = in.nextInt();
//String day = in.next();
int dd = in.nextInt();
//String year = in.next();
int yy = in.nextInt();
in.close();
LocalDate dt = LocalDate.of(yy, mm, dd);
System.out.print(dt.getDayOfWeek());

你可以使用下面的方法通过传递一个特定的日期来获取星期几，

这里对于Calendar类的set方法，难点在于month参数的索引将从0开始。

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

        Calendar cal = Calendar.getInstance();

        if(month==1){
            cal.set(year,0,day);
        }else{
            cal.set(year,month-1,day);
        }

        int dow = cal.get(Calendar.DAY_OF_WEEK);

        switch (dow) {
        case 1:
            return "SUNDAY";
        case 2:
            return "MONDAY";
        case 3:
            return "TUESDAY";
        case 4:
            return "WEDNESDAY";
        case 5:
            return "THURSDAY";
        case 6:
            return "FRIDAY";
        case 7:
            return "SATURDAY";
        default:
            System.out.println("GO To Hell....");
        }

        return null;
    }

日历类有内置的displayName功能:

Calendar.getInstance().getDisplayName(Calendar.DAY_OF_WEEK, Calendar.SHORT, Locale.getDefault()); // Thu   

Calendar.SHORT -> Thu
Calendar.LONG_FORMAT -> Thursday

Java 1.6以来可用。参见Oracle文档