填充可重用方法 Java 中使用的常量映射的最佳实践

Question

I am using a reusable method to map two codes, when we receive 'a' we want to use '01' in our code. This is a static method so is it right that it only gets created once and we reuse the method or is this bad practice and it is unnecessarily processing every time we call this method? this good practice or should I be creating this map somewhere else and just using the method for returning the values from it?

    private static String mapStatus(String duckStatus){

       
        Map<String, String> statusMap = new HashMap<String,String>();
        statusMap.put("a","01");
        statusMap.put("b","02");
        statusMap.put("c","03");

        if (!statusMap.containsKey(duckStatus)){
            throw new NullPointerException("Invalid Code does not map to status code");
        }
        return statusMap.get(duckStatus);
    }
    

Answer 1

As per the comments, enum can be a good choice but again as already mentioned by @kendavidson it is debatable. From the performance angle I don't see much of a difference between enum and HashMap here but in my opinion HashMap will be more appropriate and will provide better readability. Only difference I suggest in the code you have written is, make the HashMap statically populated so that HashMap build up time is avoided every time you want to lookup the statusMap whenever the call is made to mapStatus method. The modified code will look like below:

public class Test {
    private static final Map<String, String> STATUS_MAP = new HashMap<>();
    static {
        // Mapping the status values in Duck Creek to the Values used here
        STATUS_MAP.put("a", "01");
        STATUS_MAP.put("b", "02");
        STATUS_MAP.put("c", "03");
    }

    private static String mapStatus(String duckStatus) {
        if (!STATUS_MAP.containsKey(duckStatus)) {
            throw new IllegalArgumentException("Invalid code " + duckStatus + " does not map to status code");
        }
        return STATUS_MAP.get(duckStatus);
    }
}

Note:

1. Not sure if you wanted to check for duckStatus in duckCreekToEDMStatusMapper or STATUS_MAP , I am using STATUS_MAP
2. Instead of NullPointerException better to use IllegalArgumentException as it is appropriate here.