Get Enum Instance from Class<? extends Enum> using String value?

java class reflection enums instantiation
Craig Otis picture Craig Otis · Jul 20, 2011 · Viewed 35.9k times · Source

I'm finding it difficult to put the exact question into words, so I'll just give an example.

I have two Enum types:

enum Shape {
    CAT, DOG;
}

enum Color {
    BLUE, RED;
}

I have a method:

public Object getInstance(String value, Class<?> type);

I would like to use the method like:

// someValue is probably "RED", and someEnumClass is probably Color.class
Color c = getInstance(someValue, someEnumClass);

I've been having trouble determining exactly how to implement getInstance(). Once you know the exact Enum class that you want to instantiate, it's easy:

Color.valueOf("RED");

But how can this above line be accomplished with an unknown Class? (It is, however, known that the someEnumClass is a subclass of Enum.)

Thanks!

Answer

chahuistle picture chahuistle · Jul 20, 2011 
 public static <T extends Enum<T>> T getInstance(final String value, final Class<T> enumClass) {
     return Enum.valueOf(enumClass, value);
 }

And the method is to be used as:

final Shape shape = getInstance("CAT", Shape.class);

Then again, you can always use

final Shape shape = Shape.valueOf("CAT");

which is a shortcut for 

Enum.valueOf(Shape.class, "CAT");

Related questions

How to read the value of a private field from a different class in Java?

I have a poorly designed class in a 3rd-party JAR and I need to access one of its private fields. For example, why should I need to choose private field is it necessary? class IWasDesignedPoorly { private Hashtable stuffIWant; } IWasDesignedPoorly obj = ...; …

Read More
Check if a Class Object is subclass of another Class Object in Java

I'm playing around with Java's reflection API and trying to handle some fields. Now I'm stuck with identifying the type of my fields. Strings are easy, just do myField.getType().equals(String.class). The same applies for other non-derived classes. …

Read More
Getting Class type from String

I have a String which has a name of a class say "Ex" (no .class extension). I want to assign it to a Class variable, like this: Class cls = (string).class How can i do that?

Read More