CODEWITHSUNDEEP
javaenums
Roam
Roam

Reputation: 4949

valueOf method of Enum

Enum has a valueOf method:

public static <T extends Enum<T>> T valueOf(Class<T> enumType, String name)

So, when i have the enum:

public enum Basket {
    APPLES, ORANGES, FLOWERS 
}

the code 

Basket b = Basket.valueOf(Basket.class, "APPLES");

brings me the same object as does 

Basket b2 = Basket.APPLES;

i.e., b.equals(b2) is true out of the two lines above.

What i'm wondering is-- what is 

public static <T extends Enum<T>> T valueOf(Class<T> enumType, String name)

good for.

There may be a use of it in the reflect API-- one that i can't put together right now. outside of that, does this method has a specific use? what would be missing, if the class Enum didn't have this method?

Same for the valueOf-with-single parameter-- defined implicitly in Enum:

Basket.valueOf("APPLES");

is doing the same thing as 

Basket.valueOf(Basket.class, "APPLES");

What's the use?

Upvotes: 2

Views: 1324

Answers (1)

Adisesha
Adisesha

Reputation: 5258

public static <T extends Enum<T>> T valueOf(Class<T> enumType, String name)

is used when you don't know exact Enum type. This is the case if you are writing a generic code. One example is deserializing json to java object. You can get the 'enumType' of a field though reflection and invoke,

Enum.valueOf(enumClass,fieldValue)

If you want to see real usage, check, 

java.io.ObjectInputStream#readEnum

Upvotes: 3

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