Question

Suppose I have an interface…

public interface Feature
{
    public abstract void doSmth();
}

… and multiple enums implementing that interface:

// First enum

public enum FeatureA implements Feature
{
    A1
    {
        @Override public void doSmth() { System.out.println("A ==== A1"); }
    },

    A2
    {
        @Override public void doSmth() { System.out.println("A ==== A2"); }
    };

    @Override public abstract void doSmth();
}

//Second enum

public enum FeatureB implements Feature
{
    B1 
    {
        @Override public void doSmth() { System.out.println("B ==== B1"); }
    },

    B2
    {
        @Override public void doSmth() { System.out.println("B ==== B2"); }
    },

    B3
    {
        @Override public void doSmth() { System.out.println("B ==== B3"); }
    };

    @Override public abstract void doSmth();
}

// and many other enums implementing Feature

Now suppose I assemble a set of Strings corresponding to the names of enum constants like this (this is necessary for the third party code)…

Set<String> singleEnum = new LinkedHashSet<String>();
singleEnum.add("A2");
singleEnum.add("A1");

… and later I need to convert each String in such a set to the enum constant and then apply the doSmth() method. singleEnum contains names of FeatureA constants only, so I’m able to apply the valueOf(String) method in this case:

for (String s : singleEnum)
{
    FeatureA.valueOf(s).doSmth();
}

But what if the Strings in the set correspond to varying enum constants? E.g.:

Set<String> multipleEnums = new LinkedHashSet<String>();
multipleEnums.add("A1");
multipleEnums.add("B2");
multipleEnums.add("A2");

I would like to do something like this:

for (String s : multipleEnums)
{
    Feature./* convert s to the correct enum */.doSmth();
}

Is there an easy way to do that? The only method Eclipse allows to apply to Feature is Feature.class, and I don’t really know how to proceed from there.
I’m dealing with huge datasets, so performance is important.

Thank you.

Answer 1

You can create a Map with the name of every enum

static final Map<String, Feature> map = ...
static <F extends Enum & Feature> void addEnums(F... features) {
    for(F f: features)
       map.put(f.name(), f);
}

addEnums(FeatureA.values());
addEnums(FeatureB.values());