Best practice to look up Java Enum

Question

We have a REST API where clients can supply parameters representing values defined on the server in Java Enums.

So we can provide a descriptive error, we add this

Answer 1

Why do we have to write that 5 line code ?

public class EnumTest {
public enum MyEnum {
    A, B, C, D;
}

@Test
public void test() throws Exception {
    MyEnum.valueOf("A"); //gives you A
    //this throws ILlegalargument without having to do any lookup
    MyEnum.valueOf("RADD"); 
}
}