So in C++/C# you can create flags enums to hold multiple values, and storing a single meaningful integer in the database is, of course, trivial.
In Java you have Enu
// From Adamski's answer
public static > int encode(EnumSet set) {
int ret = 0;
for (E val : set) {
ret |= 1 << val.ordinal();
}
return ret;
}
@SuppressWarnings("unchecked")
private static > EnumSet decode(int code,
Class enumType) {
try {
E[] values = (E[]) enumType.getMethod("values").invoke(null);
EnumSet result = EnumSet.noneOf(enumType);
while (code != 0) {
int ordinal = Integer.numberOfTrailingZeros(code);
code ^= Integer.lowestOneBit(code);
result.add(values[ordinal]);
}
return result;
} catch (IllegalAccessException ex) {
// Shouldn't happen
throw new RuntimeException(ex);
} catch (InvocationTargetException ex) {
// Probably a NullPointerException, caused by calling this method
// from within E's initializer.
throw (RuntimeException) ex.getCause();
} catch (NoSuchMethodException ex) {
// Shouldn't happen
throw new RuntimeException(ex);
}
}