Interpreting abbreviations for days of the week such that they are consecutive days

Question

The code below works, but it seems it could be done better. Is there a better/more efficient way to do this?

Given:

1. All days off ("relief days") will be consecutive.
2. Relief days will be imported as a string. Days of week are represented by their first letter. "S" can represent Saturday or Sunday, "T" can represent Tuesday or Thursday. I.e., someone with Sat/Sun off would be "SS", someone with Tue/Wed/Thu off would be "TWT".
3. Depending on how many hours a day they work, they'll either have 2, 3, or 4 days off.

The existing code:

    public static String getReliefDays(){

        Map<String, String> user = new HashMap<>(); //test example user
        user.put("name", "Schmoe, Joe");
        user.put("employeeNo", "123456");
        user.put("startTime", "0800");
        user.put("endTime", "1700");
        user.put("reliefDays", "TF");

        String rd = (String) user.get("reliefDays");
        int rdLength = rd.length();
        String reliefDays = "";
        String fl = rd.substring(0, 1); //first letter in the days off string
        String sl = rd.substring(1, 2); //second letter in the days off string

        switch (fl) {
            case "S":
                if (sl.equalsIgnoreCase("M")) {
                    reliefDays = "SUN MON";
                if (rdLength == 3) {
                    reliefDays += " TUE";
                }
                if (rdLength == 4) {
                    reliefDays += " WED";
                }
            }else{
                reliefDays = "SAT SUN";
                if (rdLength == 3) {
                    reliefDays += " MON";
                }
                if (rdLength == 4) {
                    reliefDays += " TUE";
                }                    
            }
            break;
        case "M":
            reliefDays = "MON TUE";
            if (rdLength == 3) {
                reliefDays += " WED";
            }
            if (rdLength == 4) {
                reliefDays += " THU";
            }
            break;
        case "T":
            if (sl.equalsIgnoreCase("W")) {
                reliefDays = "TUE WED";
                if (rdLength == 3) {
                    reliefDays += " THU";
                }
                if (rdLength == 4) {
                    reliefDays += " FRI";
                }
            } else {
                reliefDays = "THU FRI";
                if (rdLength == 3) {
                    reliefDays += " SAT";
                }
                if (rdLength == 4) {
                    reliefDays += " SUN";
                }
            }
            break;
        case "W":
            reliefDays = "WED THU";
            if (rdLength == 3) {
                reliefDays += " FRI";
            }
            if (rdLength == 4) {
                reliefDays += " SAT";
            }
            break;
        case "F":
            reliefDays = "FRI SAT";
            if (rdLength == 3) {
                reliefDays += "SUN";
            }
            if (rdLength == 4) {
                reliefDays += " MON";
            }
            break;
        }
        return reliefDays;
    }

Answer 1

Your indentation has gone wrong here, and it's confusing:

             if (sl.equalsIgnoreCase("M")) {
                 reliefDays = "SUN MON";
             if (rdLength == 3) {
                 reliefDays += " TUE";
             }
             if (rdLength == 4) {
                 reliefDays += " WED";
             }
         }

Let your IDE help and auto-format your code as you work.

Other than that, you can get better feedback when you post not only the code you want feedback on but also the surrounding context, so that you can get feedback on how you are applying OOP and using the correct signatures.

My version is below, see how I've divided up the logic.

I figured that this job of creating a String with the weekday short names would belong to the User so I put it there.

I also thought that a Weekday class might know how to deal with the problem of disambiguating weekdays as single letters in a String that represents week days. But I can also see the argument for this to belong to User since that sort of String is known to be specifically used when creating Users. In the end, I decided that Weekday would expose the logic, and User will expose setReliefDays taking a String, which would delegate to the logic in Weekday, but then this can easily be changed if the implementation of User needs to change.

public class ReliefDays {

    public static void main(String[] args) {
        User joe = new User();
        joe.name = "Schmoe, Joe";
        joe.employeeNo = "123456";
        joe.startTime = "0800";
        joe.endTime = "1700";
        joe.setReliefDays("TFSS");
        System.out.println(joe.reliefDaysShortNames());
    }

    static class User {
        String name;
        String employeeNo;
        String startTime;
        String endTime;
        Weekday[] reliefDays;

        /**
         * Returns a string containing the short names of this user's relief days
         * seperated by spaces.
         * 
         * For example, "SAT SUN MON".
         */
        public String reliefDaysShortNames() {
            StringBuilder shortDays = new StringBuilder();
            for (int i = 0; i < reliefDays.length - 1; i++) {
                shortDays.append(reliefDays[i].shortName);
                shortDays.append(" ");
            }
            shortDays.append(reliefDays[reliefDays.length - 1].shortName);
            return shortDays.toString();
        }

        /**
         * Set this user's relief days based on a string of characters representing
         * consecutive days.
         * 
         * For example, when days is "MT", this user's relief days are set to
         * {Weekday.MONDAY, Weekday.TUESDAY}.
         */
        public void setReliefDays(String days) {
            reliefDays = Weekday.parseWeekdays(days);
        }
    }

    static enum Weekday {
        MONDAY('M', "MON"),
        TUESDAY('T', "TUE"),
        WEDNESDAY('W', "WED"),
        THURSDAY('T', "THU"),
        FRIDAY('F', "FRI"),
        SATURDAY('S', "SAT"),
        SUNDAY('S', "SUN");

        char letter;
        String shortName;

        Weekday(char letter, String shortName) {
            this.letter = letter;
            this.shortName = shortName;
        }

        /**
         * Given at least two characters representing consecutive week days, returns an
         * array of those weekdays of the same size and in the same order.
         */
        public static Weekday[] parseWeekdays(String s) {
            Weekday[] weekDays = new Weekday[s.length()];
            Weekday currentDay = firstWeekdayOfPair(s.substring(0, 2));
            Weekday nextDay;

            weekDays[0] = currentDay;
            for (int i = 1; i < s.length(); i++) {
                nextDay = currentDay.nextWeekday();
                if (s.charAt(i) != nextDay.letter) {
                    throw new IllegalArgumentException("Unexpected sequence of days: "
                            + currentDay.letter + s.charAt(i));
                }
                weekDays[i] = nextDay;
                currentDay = nextDay;
            }
            return weekDays;
        }

        private static Weekday firstWeekdayOfPair(String s) {
            switch (s) {
            case "MT":
                return MONDAY;
            case "TW":
                return TUESDAY;
            case "WT":
                return WEDNESDAY;
            case "TF":
                return THURSDAY;
            case "FS":
                return FRIDAY;
            case "SS":
                return SATURDAY;
            case "SM":
                return SUNDAY;
            default:
                throw new IllegalArgumentException("Unexpected weekday pair: " + s);
            }
        }

        private Weekday nextWeekday() {
            switch (this) {
            case MONDAY:
                return TUESDAY;
            case TUESDAY:
                return WEDNESDAY;
            case WEDNESDAY:
                return THURSDAY;
            case THURSDAY:
                return FRIDAY;
            case FRIDAY:
                return SATURDAY;
            case SATURDAY:
                return SUNDAY;
            case SUNDAY:
                return MONDAY;
            default:
                throw new IllegalArgumentException("Unexpected day: " + this.toString());
            }
        }

    }

}