Initializing enum variables in a comparison function

Question

I am having trouble comparing an Enum value to a predefined value within a function.
I have an Enum setup as

public enum SomeEnum {
    A, B, C
}

Then in another class, I have a method which compares a String to the Enum values, and returns the Enum value if they are equals according to the toString() method of the Enum value.

The Method:

 /**
 * Example
 * @param someString - A string which could be equivalent to an SomeEnum value.
 * @return SomeEnum Type
 */
private static ClassA someMethod(String someString) {
    SomeEnum letterType; // Problem
    for (SomeEnum letter : SomeEnum.values()) {
        if (someString.equals(letter.toString())) {
            letterType = letter;
        }
    }
    return letterType;
}

The above code gives me an error stating that:

the variable letterType may have not been initialized

Fair enough, just instantiate it!...

SomeEnum letterType = new SomeEnum(); // NO

However Enums (by definition) cannot be instantiated.

This leaves me with 2 options:

1. Initialize letterType on first use (within the if)

2. Initialize letterType by assigning it null

   /*Options*/
   //1. 
   if (someString.equals(letter.toString())){
       SomeEnum letterType = letter;
   }
   //2. 
   private static ClassA someMethod(String someString) {
       SomeEnum letterType = null;
       //...
   }
   

---

Option 1 restricts me returning letterType as it is now not reachable.
Option 2 works, however instantiating with null seems like it is not good practice - correct me if I am wrong.

Besides using a switch statement and changing the function, it seems I am only able to achieve this using Option 2.

Is there another way to achieve this?/missing something simple..?
Is my understanding of this concept incorrect...?
Should I just be using a switch statement instead?