简单地使用SimpleDateFormat。

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy", java.util.Locale.ENGLISH);
Date myDate = sdf.parse("28/12/2013");
sdf.applyPattern("EEE, d MMM yyyy");
String sMyDate = sdf.format(myDate);

结果是:2013年12月28日星期六

默认构造函数接受“默认”区域设置，因此在需要特定模式时要小心使用它。

public SimpleDateFormat(String pattern) {
    this(pattern, Locale.getDefault(Locale.Category.FORMAT));
}

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。

简单地使用SimpleDateFormat。

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy", java.util.Locale.ENGLISH);
Date myDate = sdf.parse("28/12/2013");
sdf.applyPattern("EEE, d MMM yyyy");
String sMyDate = sdf.format(myDate);

结果是:2013年12月28日星期六

默认构造函数接受“默认”区域设置，因此在需要特定模式时要小心使用它。

public SimpleDateFormat(String pattern) {
    this(pattern, Locale.getDefault(Locale.Category.FORMAT));
}

//to get day of any date

import java.util.Scanner; 
import java.util.Calendar; 
import java.util.Date;

public class Show {

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


            String input_date = month+"/"+day+"/"+year;

            Date now = new Date(input_date);
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(now);
            int final_day = (calendar.get(Calendar.DAY_OF_WEEK));

            String finalDay[]={"SUNDAY","MONDAY","TUESDAY","WEDNESDAY","THURSDAY","FRIDAY","SATURDAY"};

            System.out.println(finalDay[final_day-1]);

    }

    public static void main(String[] args) { 
            Scanner in = new Scanner(System.in); 
            String month = in.next(); 
        String day = in.next();
            String year = in.next();

            getDay(day, month, year);
    }

}

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;
}

添加了另一种完全符合OP要求的方法，而不使用最新的内置方法:

public static String getDay(String inputDate) {
    String dayOfWeek = null;
    String[] days = new String[]{"Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"};

    try {
        SimpleDateFormat format1 = new SimpleDateFormat("dd/MM/yyyy");
        Date dt1 = format1.parse(inputDate);
        dayOfWeek = days[dt1.getDay() - 1];
    } catch(Exception e) {
        System.out.println(e);
    }

    return dayOfWeek;
}