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?

Answer 1

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);       } } 

Answer 2

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.