Java Null值判斷

1. Java8 Optional

Map<String, String> map = Optional.ofNullable(params).orElse(new HashMap<>());

Integer sum = userService.getUserSum(dto);
sum = Optional.ofNullable(sum).orElse(0);

BigDecimal total = userFreeService.getUserFreeSum(dto);
total = Optional.ofNullable(total).orElse(BigDecimal.ZERO);
           

2. Vavr try

用過Optional；那用過Try麼