同一个美丽而聪慧的人相处，能使人紧张的神经放松，感情变得柔和——巴尔扎尔
引入依赖：
<!-- https://search.maven.org/artifact/io.github.vampireachao/stream-query --> <dependency> <groupId>io.github.vampireachao</groupId> <artifactId>stream-core</artifactId> <version>1.1.12</version> </dependency>
编写代码：
@Test void test() { class User { public GenderEnum getGender() { return null; } } String exceptionMessage = null; User user = new User(); try { require(user::getGender); } catch (IllegalArgumentException e) { exceptionMessage = e.getMessage(); } Assertions.assertEquals("'gender'需要'MALE|FEMALE'其一", exceptionMessage); } @SuppressWarnings("unchecked") public static <T extends Enum<T>> void require(SerSupp<T> enumSupp) { LambdaExecutable executable = LambdaHelper.resolve(enumSupp); Enum<T>[] enumConstants = ((Class<Enum<T>>) executable.getReturnType()).getEnumConstants(); Sf.of(enumSupp.get()).require(() -> new IllegalArgumentException( "'" + BeanHelper.getPropertyName(executable.getName()) + "'需要'" + Steam.of(enumConstants).map(Enum::name).join("|") + "'其一")); }
当你使用require(user::getGender)时，如果gender为null，则会抛出异常，并提示：'gender'需要'MALE|FEMALE'其一
这里获取了getGender的lambda方法名称，以及返回值枚举类型，通过遍历枚举的name列举选项，拼接为字符串
