如何正确使用Java 8 Optional可以有条件地返回值或抛出异常？

Question

我想实现类似下面的代码来验证我的输入,@RestController以便我可以避免显式空检查,但是我被卡住了.

public @ResponseBody Response getCityDetails(@RequestParam("city") final String city) {
    Optional.of(city).ifPresent(name -> {
        // return value
        return service.getDetails(name);
    }).orElseThrow(//some Exception);
}

Answer 1

试试这个

Optional.ofNullable(city)
        .map(name ->service.getDetails(name))
        .orElseThrow(//some Exception);