Get the name of enum based on the value

Question

I have the following enum

public enum AppointmentSlotStatusType {

    INACTIVE(0), ACTIVE(1);

    private int value;

    private AppointmentSlotStatusType(int value) {
        this.value = value;
    }

    public int getValue() {
        return value;
    }

    public String getName() {
        return name();
    }
}

How do I get the enum name if a value is known for instance 1 ?

Implement a `valueOf`-style method. – Sotirios Delimanolis Oct 15 '13 at 15:41 — Sotirios Delimanolis, Oct 15 '13 at 15:41

score 6 · Accepted Answer · answered Oct 15 '13 at 15:43

6

For this specific enum it's easy

String name = TimeUnit.values()[1].name();

answered Oct 15 '13 at 15:43

Evgeniy Dorofeev

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I would add that the `number` field is useless as there is an `ordinal` field already. – Boris the Spider Oct 15 '13 at 15:44
@BoristheSpider It's a bad idea to use `ordinals` for various reasons. – Rohit Jain Oct 15 '13 at 15:56

Rohit Jain · Answer 2 · 2013-10-15T15:52:04.327

1

You can implement a public static method inside the enum, which will give you the enum instance for that id:

public static AppointmentSlotStatusType forId(int id) {
    for (AppointmentSlotStatusType type: values()) {
        if (type.value == id) {
            return value;
        }
    }
    return null;
}

Probably you would also like to cache the array returned by values() in a field:

public static final AppointmentSlotStatusType[] VALUES = values();

then use VALUES instead of values().

Or you can use a Map instead.

private static final Map<Integer, AppointmentSlotStatusType> map = new HashMap<>();

static {
    for (AppointmentSlotStatusType type: values()) {
        map.put(type.value, type);
    }
}

public static AppointmentSlotStatusType forId(int id) {
    return map.get(id);
}

edited Oct 15 '13 at 15:52

answered Oct 15 '13 at 15:42

Rohit Jain

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In your opinion, should the method really return `null` or throw an `Exception`? – Sotirios Delimanolis Oct 15 '13 at 15:43
If you're going to cache then use a `Map` - that's O(1) instead of O(n)... – Boris the Spider Oct 15 '13 at 15:45
@SotiriosDelimanolis I guess there is no issue with returning `null` here. – Rohit Jain Oct 15 '13 at 15:45

score 0 · Answer 3 · edited May 23 '17 at 12:10

You can maintain a Map to hold name for Integer key.

public enum AppointmentSlotStatusType {
    INACTIVE(0), ACTIVE(1);

    private int value;

    private static Map<Integer, AppointmentSlotStatusType> map = new HashMap<Integer, AppointmentSlotStatusType>();

    static {
        for (AppointmentSlotStatusType item : AppointmentSlotStatusType.values()) {
            map.put(item.value, item);
        }
    }

    private AppointmentSlotStatusType(final int value) { this.value = value; }

    public static AppointmentSlotStatusType valueOf(int value) {
        return map.get(value);
    }
}

Take a look at this answer.

Why not just vote to close this as a duplicate? Where do you see the difference between this question and the one you linked to? — Jon Skeet, Oct 15 '13 at 15:43

Get the name of enum based on the value

3 Answers3