Array with enumerated elements

Question

Java program uses the following construction: (provided mainly for context)

public class Utils {
  public static final byte PROVIDER_FOO = 0;
  public static final byte PROVIDER_MOO = 1;
  public static final byte PROVIDER_BAR = 2;
  public static final byte PROVIDER_FUR = 3;
  public static final byte PROVIDER_BOO = 4;
  public static final byte PROVIDER_ANOTHER_FOO = 5;
  public static final byte PROVIDER_YET_ANOTHER = 6;

  public static String [] PROVIDERS = {"FOO", "MOO", "BAR", "FUR", "BOO",
    "PROVIDER_ANOTHER_FOO", "PROVIDER_YET_ANOTHER"};

  ...

}

So, each element of array has a number. And each array index in range 0..6 has text representation. Text representation is using in outer world: reading configs, printing results. Number representation is using in internal tasks. So, there a problem to transform text representation to number and vice versa. Number is transferring to string as following:

// someObject.getProviderNumeric() returns numeric value for someObj's provider
String strProvider = Utils.PROVIDERS[someObj.getProviderNumeric()] 

String is transferring to number like this:

int getNumericByText(String strProvider) {
  for (int i = 0; i < Utils.PROVIDER_YET_ANOTHER; ++i) {
    if (strProvider.equals(Utils.PROVIDERS[i])) {
      return i;
  }
  return -1;
}

It looks pretty bulky. What is the best way to rewrite?

Answer 1

In my opinion, what you need is an enum.

Use an enum and I believe what you are looking for will be provided for you.

public enum Utils {
    PROVIDER_FOO, PROVIDER_MOO, PROVIDER_BAR, PROVIDER_FUR,
    PROVIDER_BOO, PROVIDER_ANOTHER_FOO, PROVIDER_YET_ANOTHER;
}

String to int:

Utils.valueOf(str).ordinal();

int to String:

Utils.values()[intValue].name();

Or if you want to be a bit more advanced, I suggest reading this answer of mine

Answer 2

The obvious solution is to use an enum with custom fields for the numeric value and the custom string representation, and a static map to cache the mapping of string values to the enumerated values. Something like this:

enum Provider {
    FOO(0, "Foo"),
    MOO(1, " Moo"),
    BAR(2, "Bar");

    private final byte value;
    private final String label;

    private static final Map<String, Provider> map;
    static {
        map = new HashMap<>();
        for (Provider provider : Provider.values()) {
            map.put(provider.label, provider);
        }
    }

    private Provider(byte value, String label) {
        this.value = value;
        this.label = label;
    }

    public static Provider fromString(String label) {
        return map.get(label);
    }
}