Adding values to HashMap

I want to add values to a HashMap, which would be used by methods in the same class. I have two solutions:

1. Adding all the values with static


2. When the first method is called, add the values

Solution #1:

private static Map<Character, String> codes = new HashMap<>();

static {
    codes.put('A', ".-");
    codes.put('B', "-...");
    codes.put('C', "-.-.");
    codes.put('D', "-..");
    codes.put('E', ".");
    codes.put('F', "..-.");
    // ...
}

Solution #2:

boolean methodIsCalled = false;

public static char decode(String s) {
    if(!methodIsCalled) {
        addValues();
    }
    // ...
}

private static void addValues() {
    codes.put('A', ".-");
    codes.put('B', "-...");
    codes.put('C', "-.-.");
    codes.put('D', "-..");
    codes.put('E', ".");
    codes.put('F', "..-.");
    // ...
}

Which one is the most efficient? Which one is the best practice?