How to get enum's numeric value?

Question

Suppose you have

public enum Week {
    SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
}

How can one get int representing that Sunday is 0, Wednesday is 3 etc?

Istvan Devai · Accepted Answer · 2012-07-18T20:59:50.307

93

Week week = Week.SUNDAY;

int i = week.ordinal();

Be careful though, that this value will change if you alter the order of enum constants in the declaration. One way of getting around this is to self-assign an int value to all your enum constants like this:

public enum Week 
{
     SUNDAY(0),
     MONDAY(1)

     private static final Map<Integer,Week> lookup 
          = new HashMap<Integer,Week>();

     static {
          for(Week w : EnumSet.allOf(Week.class))
               lookup.put(w.getCode(), w);
     }

     private int code;

     private Week(int code) {
          this.code = code;
     }

     public int getCode() { return code; }

     public static Week get(int code) { 
          return lookup.get(code); 
     }
}

edited Jul 18 '12 at 20:59

answered Jul 18 '12 at 20:52

Istvan Devai

3,962
23
21

2

+1 for providing a nice answer where a 1-liner would have been sufficient – avalancha Dec 02 '13 at 09:07
One liner: `final int i = Week.SUNDAY.ordinal();` – propatience Feb 08 '23 at 10:35

score 9 · Answer 2 · answered Jul 18 '12 at 20:54

You can call:

MONDAY.ordinal()

but personally I would add an attribute to the enum to store the value, initialize it in the enum constructor and add a function to get the value. This is better because the value of MONDAY.ordinal can change if the enum constants are moved around.

score 2 · Answer 3 · answered Jul 18 '12 at 20:54

2

Take a look at the API it is usually a decent place to start. Though I would not have guessed without having run into this before that you call ENUM_NAME.ordinal()

answered Jul 18 '12 at 20:54

John Kane

4,383
1
24
42

score 0 · Answer 4 · answered Sep 28 '17 at 06:37

Yeah, Simply use the ordinal method of enum object.

public class Gtry {
  enum TestA {
    A1, A2, A3
  }

  public static void main(String[] args) {
    System.out.println(TestA.A2.ordinal());
    System.out.println(TestA.A1.ordinal());
    System.out.println(TestA.A3.ordinal());
  }

}

API:

/**
     * Returns the ordinal of this enumeration constant (its position
     * in its enum declaration, where the initial constant is assigned
     * an ordinal of zero).
     *
     * Most programmers will have no use for this method.  It is
     * designed for use by sophisticated enum-based data structures, such
     * as {@link java.util.EnumSet} and {@link java.util.EnumMap}.
     *
     * @return the ordinal of this enumeration constant
     */
    public final int ordinal() {
        return ordinal;
    }

5 years late and not better than any of the previous answers — NoDataDumpNoContribution, Jan 03 '18 at 20:43
@Trilarion, Now you are 5+ years late do you have any better answers? ;) — Ganesa Vijayakumar, Jan 04 '18 at 04:55

How to get enum's numeric value?

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