How to convert an Object to enum to use it in a switch statment

Question

Using Java 8, I have a Map that I need to convert to another Map replacing the key names and sometimes the value. E.g., when they turn out to be enums in which case I need to convert these enums to other constants (Strings and sometimes ints). I do not want to compare Strings, i.e. theEnum.name(), due to possible duplicates but would prefer to convert the Object to an enum and switch on it. However, I fail to find a way to convert the Object to a switchable enum. Enum.valueOf does not return something that can be switched upon (see the example below).

private void put(String key, Object value) {
  if (value != null && value.getClass().isEnum()) {
  Enum<?> val = (Enum<?>)value; 
  /* The below line has the following problem:
   * Cannot switch on a value of type Enum. 
   * Only convertible int values, strings or enum variables are 
   * permitted */
  switch (Enum.valueOf(val.getClass(), val.name())) {
    case EmploymentType.FULL_TIME_EMPLOYEE : value = "Fast anställd";
         break;
    case ResidenceType.TENANCY : value = "Hyresrätt";
         break;
    default : break;
  }
}
map.put(key, value);    

}

I am aware that I could do:

private void put(String key, Object value) {
  if (value != null && value.getClass().isEnum()) {
    if (value.equals(EmploymentType.FULL_TIME_EMPLOYEE) value = "Fast anställd";
    else if (value.equals(ResidenceType.TENANCY) value = "Hyresrätt";
  }
  map.put(key, value);    
}

But is find that to be much less elegant and as easy to read as a switch statement would be. Is there a way to do that?

Answer 1

It looks like you have to deal with multiple enum types. But you can't switch accross multiple enum types in one switch statement. I think you could just use a Map<Enum<?>, Object> instead.

You could setup an HashMap like this:

Map<Enum<?>, Object> enumMap = new HashMap<>();
enumMap.put(EmploymentType.FULL_TIME_EMPLOYEE, "Fast anställd");
enumMap.put(ResidenceType.TENANCY, "Hyresrätt");

and use it like this:

if (enumMap.containsKey(value)) {
    value = enumMap.get(value);
}
map.put(key, value);

Answer 2

One possibility would be to have the enums implement an interface with a getValue() or similar method. Even if it were possible to switch between different enums, that code isn't very elegant.

Then you could just write

if (value != null && value instanceof MyInterface) {
    MyInterface foo = (MyInterface) value;
    value = foo.getValue();   // Although it's a bit ugly to reassign a parameter
}
map.put(key, value);