The method is undefined for the type T

Question

I am trying this example, but can't make it work; it throws The method getFromInt(int) is undefined for the type T

T is a generic enum type

public static <T> T deserializeEnumeration(InputStream inputStream) {
        int asInt = deserializeInt(inputStream);
        T deserializeObject = T.getFromInt(asInt);
        return deserializeObject;
    }

am calling the previous method as follows for example:

objectToDeserialize.setUnit(InputStreamUtil.<Unit>deserializeEnumeration(inputStream));

or

objectToDeserialize.setShuntCompensatorType(InputStreamUtil.<ShuntCompensatorType>deserializeEnumeration(inputStream));

or etc...

Answer 1

You can hack your way around this. As you've stated in the comments:

I have some enums which all have getFromInt method

With a slight adaptation to the method, by adding a new parameter, the type of the enum, you can use reflection to invoke said getFromInt method:

public static <T> T deserializeEnumeration(Class<? extends T> type, InputStream inputStream){
    try {
        int asInt = deserializeInt(inputStream);
        // int.class indicates the parameter
        Method method = type.getDeclaredMethod("getAsInt", int.class);
        // null means no instance as it is a static method
        return method.invoke(null, asInt);
    } catch(NoSuchMethodException, InvocationTargetException, IllegalAccessException e){
       throw new IllegalStateException(e);
    }
}