Cannot get a value from a map with enum key

Question

Write a code and find the get operation fails to obtain the value from a map with enum key.

For example, the checkers is initilized, then the get operations always return null. Why

class Test {
    static void main(String[] args){
        Map<CHANA_OPERATION, Closure> checkers = [VIDEO_GENERATION: (userId) -> {
            System.out.println("..............")
        }, TEXT_API_CALL: (userId)->{
            return false
        }]

        checkers.get(CHANA_OPERATION.VIDEO_GENERATION).call(1)
    }


    enum CHANA_OPERATION{
        VIDEO_GENERATION(0),
        TEXT_API_CALL(1),
        TEXT_VIDEO_API_CALL(2)

        int code
        CHANA_OPERATION(int code){
            this.code = code
        }
    }

}

Exception in thread "main" java.lang.NullPointerException: Cannot invoke method call() on null object
    at org.codehaus.groovy.runtime.NullObject.invokeMethod(NullObject.java:110)
    at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:44)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
    at org.codehaus.groovy.runtime.callsite.NullCallSite.call(NullCallSite.java:34)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:139)
    at com.chana.application.service.impl.Test.main(Test.groovy:11)

Answer 1

You are not actually using the enum here. The map literal in Groovy uses String keys and the quotes are optional (if the key can be parsed as one token).

To use proper values for the keys, you have to put the value inside parenthesis. You also have to reference the enum-class.

E.g.

Map<CHANA_OPERATION, Closure> checkers = [
    (CHANA_OPERATION.VIDEO_GENERATION): { userId ->
//  X~~~~~~~~~~~~~~~~                X
        println "userId=$userId"
    }, //...
]