Efficiently converting java string to its equivalent enum

Question

Given a string i want to get the enum equivalent of it in constant time. I have a enum defined like the one shown in the question. Best way to create enum of strings?

Answer 1

Since Enum.valueOf operates on the built-in name of the enum (i.e. "STRING_ONE" and "STRING_TWO") you would need to roll your own "registry" of name-to-enum, like this:

public enum Strings {
    STRING_ONE("ONE"),
    STRING_TWO("TWO")
    ;
    private static final Map byName = new HashMap();
    private final String text;

    private Strings(final String text) {
        this.text = text;
    }
    static {
        for (Strings s : Strings.values()) {
            byName.put(s.toString(), s);
        }
    }
    @Override
    public String toString() {
        return text;
    }
    public static Strings forName(String name) {
        return byName.get(name);
    }
}

Demo.

Above, a map from string name to enum Strings is used to do the translation. If the name is not there, null would be returned from the Strings.forName method.