CODEWITHSUNDEEP
javagenerics
Inquisitive
Inquisitive

Reputation: 7856

Why compiler is failing to infer return type of my method?

Here's my code .Basically I trying to return a Map from my intToEnumMap method.But compiler is not allowing this.Why can't the compiler infer the return type for my method?

  public enum  INVALIDTHRESHOLDSTATE{
        ONE(0,GAUGE_MIN_LOWER_THRESHOLD1_MESSAGE),
        TWO(1,GAUGE_THRESHOLD1_LOWER_THRESHOLD2_MESSAGE),
        THREE(2,GAUGE_THRESHOLD2_LOWER_MAX_MESSAGE);

        private static final Map<Integer,INVALIDTHRESHOLDSTATE> intToEnum = new HashMap<Integer, INVALIDTHRESHOLDSTATE>();
        static {

            int i=0;
            for (INVALIDTHRESHOLDSTATE invalidState : values()){
                i++;
                intToEnum.put(Integer.valueOf(i), invalidState);
            }      
        }

        private int value;
        private String message;

        private INVALIDTHRESHOLDSTATE(int value,String message){
            this.value = value;
            this.message = message;
        }
        public int getValue() {
             return value;
          }
        public String getString() {
             return message;
          }

        // Generic method
        public static <K,V> Map<K,V> intToEnumMap() {
           return intToEnum;  //doesn't compile
                 ^^^^^^^^^
        }


    }

Upvotes: 3

Views: 109

Answers (1)

Jon Skeet
Jon Skeet

Reputation: 1504172

You've created a generic method, so anyone could call:

Map<String, Long> map = INVALIDTHRESHOLDSTATE.<String, Long> intToEnumMap();

I assume that's not what you intended - if you're returning intToEnum it looks to me like you don't want the callers to specify generic type arguments at all, and it should just be:

public static Map<Integer, INVALIDTHRESHOLDSTATE> intToEnumMap() {
    return intToEnum;
}

(I'd also strongly suggest renaming your enum to follow normal Java naming conventions, but that's a different matter.)

Upvotes: 8

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