Calculating number bonds to value in Java-CodePudding

As part of my application, the database stores "badges" in a user's record in the database. I use the bitwise operator as (as far as I know) no two additions of them can have the same solution. Here are the values:

enum Badge {
        SUPPORTER(1),
        ALPHA(1 << 1),
        BETA_OWNER(1 << 2),
        BOOSTER(1 << 3),
        ONE_MONTH(1 << 4),
        THREE_MONTH(1 << 5),
        SIX_MONTH(1 << 6),
        ONE_YEAR(1 << 7),
        TWO_YEAR(1 << 8),
        ;

        public int value;
        
        public int resolve() {
            return value;
        }

        Badge(int i) {
            value = i;
        }
    }

The method of storing them is as simple as adding up the values of each badge corresponding to the user. However, decoding this value is more tricky.

How would I go about decoding the value from the database into a list of badges that I can manipulate?

CodePudding user response：

Use an EnumSet.The EnumSet can hold each item only once (it's a set). Have a look here for storing values in a database. There are solutions for decoding manually, or you can use Apache Commons for that.

CodePudding user response：

Lets try something like this:

public enum BADGES {SUPPORTER, ALPHA, BETA_OWNER, BOOSTER, ONE_MONTH, THREE_MONTH, SIX_MONTH, ONE_YEAR, TWO_YEAR};

public HashMap<BADGES, Integer> badgesToIntegerMap = /* initialize map where integers are mapped to badges */

public HashMap<Integer, BADGES> integerToBadgesMap = /* initialize map where badges are mapped to their integers */

public List<BADGES> getUserBadges(int userStatus) {
    List<BADGES> retVal = new ArrayList<BADGES>();
    // Start from highest one, being TWO_YEAR at time of writing
    int currentBadge = 1 << 8;  //
    while (currentBadge > 0) {  // These two should be replaced by iterating the badgesToIntegerMap's values
        if (userStatus && currentBadge == 1) {
            retVal.add(integerToBadgesMap.get(currentBadge));
        }
        currentBadge = currentBadge >> 1;
    }
    
    return retVal;
}

Or you know, just pass these integers into a constructor of each individual badge, and you can avoid one lookup.