java enum getter setter

Question

I'm consuming data from web service, will be storing that data into data holder classes and then get that data at some other place.

For a particular field, most suitable data type is enum and hence I've created following enum:

public enum EventStatus {
    PENDING(1), OPEN(2), DISPATCHED(3), APPENDED(4), CLOSED(5), REQUESTED_TO_CLOSE(
            6), ACTION_REQUESTED_FROM_POLICE_STATION(7), ACTION_REQUESTED_FROMD_ISPATCHER(
            8), ACTION_REQUESTED_FROM_SUPERVISOR(9);
    private int value;

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

    public int getValue() {
        return value;
    }
    //Just for testing from some SO answers, but no use
    public void setValue(int value) {
        this.value = value;
    }
}

This enum is used within another class as follows:

public EventStatus getEventStatus() {
    return eventStatus;
}

public void setEventStatus(EventStatus eventStatus) {
    this.eventStatus = eventStatus;
}

Now when I try to set value like following:

event.setEventStatus(getAttributeValueInt(linkedEventElement, "status"));

which equivalents to

event.setEventStatus(1);

I'm getting compilation error that method is not applicable for arguments(int)

One way I can do this is by something like this:

switch(getAttributeValueInt(linkedEventElement, "status")){
   case 1:eventLinkedEvent.setEventStatus(EventStatus.PENDING); 
      //and so on...
}

But this ruins the sole purpose of enum.

Also how to get event status value in integer form?

Can anyone please guide me how to go ahead?

Solution 1

You can create enum like this

public enum EventStatus {
    PENDING(1), OPEN(2), DISPATCHED(3), APPENDED(4), CLOSED(5), REQUESTED_TO_CLOSE(
            6), ACTION_REQUESTED_FROM_POLICE_STATION(7), ACTION_REQUESTED_FROMD_ISPATCHER(
            8), ACTION_REQUESTED_FROM_SUPERVISOR(9);
    private int value;

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

    public int getValue() {
        return value;
    }
    //Just for testing from some SO answers, but no use
    public void setValue(int value) {
        this.value = value;
    }

    public static EventStatus getEventStatusById(int id) {

        EventStatus event = null;

        switch (id) {
        case 1:
            event = PENDING;
            break;
        case 2:
            event = OPEN;
            break;
        case 3:
            event = DISPATCHED; 
            break;
        case 4:
            event = APPENDED;
            break;
        case 5:
            event = CLOSED;
            break;
        case 6:
            event = REQUESTED_TO_CLOSE;
            break;
        case 7:
            event = ACTION_REQUESTED_FROM_POLICE_STATION;
            break;
        case 8:
            event = ACTION_REQUESTED_FROMD_ISPATCHER;
            break;
        case 9:
            event = ACTION_REQUESTED_FROM_SUPERVISOR;
            break;

        default:
            break;
        }
        return event;
    }
}

after you can try below line to set EventStatus

event.setEventStatus(EventStatus.getEventStatusById(getAttributeValueInt(linkedEventElement, "status")));

I think its useful..

Solution 2

Create a mapping in enum itself from value to enum constant. And then a static method, which takes an int type and returns the enum type.

public enum EventStatus {
    // constants
    ;
    private final static Map<Integer, EventStatus> REVERSE_MAP = new HashMap<>();

    static {
        for (EventStatus status: values()) {
            REVERSE_MAP.put(status.value, status);
        }
    }

    public static EventStatus forValue(int value) {
        return REVERSE_MAP.get(value);
    }
}

Solution 3

An enum is a class. It's not a simple alias to an int as it is in C for example. 1 is an integer, not an instance of EventStatus, and your method expects an instance of EventStatus, so that doesn't compile.

Just provide a factory method in the enum to transform an int value to the enum:

public static EventStatus fromIntValue(int value) {
    // iterate through the enum constants, returned by EventStatus.value(), 
    // and find the one with the given value
}

You could also store the enum constants in a Map<Integer, EventStatus> to make the lookup O(1).

Solution 4

Quick solution, since your ordinals (Enum indexes) match your values (with a difference of 1), modify your Enum EventStatus to include new array of EventStatus:-

public enum EventStatus {
    PENDING(1), OPEN(2), DISPATCHED(3), APPENDED(4), CLOSED(5), REQUESTED_TO_CLOSE(
            6), ACTION_REQUESTED_FROM_POLICE_STATION(7), ACTION_REQUESTED_FROMD_ISPATCHER(
            8), ACTION_REQUESTED_FROM_SUPERVISOR(9);
    private int value;

    public static final EventStatus values[] = values();

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

    public int getValue() {
        return value;
    }
    //Just for testing from some SO answers, but no use
    public void setValue(int value) {
        this.value = value;
    }
}

Now instead of this:-

event.setEventStatus(getAttributeValueInt(linkedEventElement, "status"));

Use this:-

event.setEventStatus(EventStatus.values[(getAttributeValueInt(linkedEventElement,"status"))-1)]);

This will return Enum value for corresponding ordinal value, For example:-

EventStatus.values[1-1]; //this will return EnumStatus.PENDING

-1 is because you have provided your ordinal values starting from 1.

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