java Enum valueOf has two parameters?

Question

Why does valueOf have two parameters?

in Java documentation for valueOf

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

Parameters:

enumType - the Class object of the enum type from which to return a constant

name - the name of the constant to return

But most examples I read online says:

enum WorkDays {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY;
}

Test:

WorkDays day1 = WorkDays.valueOf("MONDAY");
System.out.println(day1); // >>>  MONDAY

It seems that the method used only one parameter?

Answer 1

As you indicated in previous comments that you find the text in the documentation confusing, and since your profile indicates you are a novice programmer:

Enum is the superclass of all enums you will declare. In your example, WorkDays can be seen as a specific case of the Enum class. The valueOf() static method documentation is writen for this parent Enum class. Meaning that in your case, it would be called as: Enum.valueOf(WorkDays.class, "MONDAY").

Now, since you made your own Enum (i.e. WorkDays), you don't need to use this static parent method. You can just use the method that is exposed by your self-created enum.

WorkDays.valueOf("Monday")

This is "implicitly declared" meaning that there it will be there for every one of your self-created enums.