指定为non-null的参数在Kotlin中为空

Question

我创建了一个UserWork Entity类，它包含5个元素，其中5个2元素是枚举类型。但当我试图访问那个实体类时插入它的时候会在枚举上抛出空指针异常数据。获取以下错误类型

java.lang.NullPointerException: Parameter specified as non-null is null: method com.nilmani.workmanagement.model.request.ReqWork.<init>, parameter fIxWork
at com.nilmani.workmanagement.model.request.ReqWork.<init>(ReqWork.kt) ~[main/:na]
at com.nilmani.workmanagement.model.request.ReqWork.<init>(ReqWork.kt:10) ~[main/:na]
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500) ~[na:na]
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481) ~[na:na]
at kotlin.reflect.jvm.internal.calls.CallerImpl$Constructor.call(CallerImpl.kt:41) ~[kotlin-reflect-1.5.31.jar:1.5.31-release-548(1.5.31)]
at kotlin.reflect.jvm.internal.KCallableImpl.callDefaultMethod$kotlin_reflection(KCallableImpl.kt:173) ~[kotlin-reflect-1.5.31.jar:1.5.31-release-548(1.5.31)]
at kotlin.reflect.jvm.internal.KCallableImpl.callBy(KCallableImpl.kt:112) ~[kotlin-reflect-1.5.31.jar:1.5.31-release-548(1.5.31)]
at org.springframework.beans.BeanUtils$KotlinDelegate.instantiateClass(BeanUtils.java:867) ~[spring-beans-5.3.12.jar:5.3.12]
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:196) ~[spring-beans-5.3.12.jar:5.3.12]
at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.constructAttribute(ModelAttributeMethodProcessor.java:332) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.createAttribute(ModelAttributeMethodProcessor.java:220) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor.createAttribute(ServletModelAttributeMethodProcessor.java:85) ~[spring-webmvc-5.3.12.jar:5.3.12]
at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:147) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:179) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:146) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.12.jar:5.3.12]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.3.12.jar:5.3.12]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:681) ~[tomcat-embed-core-9.0.54.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.12.jar:5.3.12]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.54.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.54.jar:9.0.54]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.12.jar:5.3.12]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1722) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]

Userwork.kt

package com.nilmani.workmanagement.entity
import com.nilmani.workmanagement.enum.FIxWork
import com.nilmani.workmanagement.enum.MaterialType
import java.time.LocalDate
import java.time.LocalDateTime
import javax.persistence.*
@Entity
data class UserWork(
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
val id:Long=-1,
//    @OneToOne(mappedBy = "userWork")
//    val user: User,
val userId:Long=-1,
@Enumerated(EnumType.STRING)
@Column(nullable = false)
val materialType: MaterialType,
@Enumerated(EnumType.STRING)
@Column(nullable = false)
val fIxWork: FIxWork,
val pieces:Int=0,
val workDate:LocalDateTime= LocalDateTime.now()
)

ReqWork.kt

package com.nilmani.workmanagement.model.request
import com.nilmani.workmanagement.enum.FIxWork
import com.nilmani.workmanagement.enum.MaterialType
import java.time.LocalDateTime
import javax.persistence.Column
import javax.persistence.EnumType
import javax.persistence.Enumerated
data class ReqWork (
val userId:Long=-1,
@Enumerated(EnumType.STRING)
@Column(nullable = false)
val materialType: MaterialType,
@Enumerated(EnumType.STRING)
@Column(nullable = false)
val fIxWork: FIxWork ,
val pieces:Int=0,
val workDate: LocalDateTime = LocalDateTime.now(),
)

UserWorkService.kt

package com.nilmani.workmanagement.service
import com.nilmani.workmanagement.entity.UserWork
import com.nilmani.workmanagement.model.request.ReqWork
import com.nilmani.workmanagement.repository.UserWorkRepository
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.stereotype.Service
import java.time.LocalDateTime
@Service
class UserWorkService {
@Autowired
private lateinit var userWorkRepository: UserWorkRepository
fun addWork(request:ReqWork):UserWork{
val newWork = UserWork(
userId = request.userId,
materialType = request.materialType,
fIxWork = request.fIxWork,
pieces = request.pieces,
workDate = LocalDateTime.now(),
)
return userWorkRepository.save(newWork)
}
}

AdminWorkController.kt

package com.nilmani.workmanagement.controller
import com.nilmani.workmanagement.entity.UserWork
import com.nilmani.workmanagement.model.request.ReqWork
import com.nilmani.workmanagement.model.response.RespWork
import com.nilmani.workmanagement.service.UserWorkService
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.http.HttpStatus
import org.springframework.http.ResponseEntity
import org.springframework.web.bind.annotation.ModelAttribute
import org.springframework.web.bind.annotation.PostMapping
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RestController
@RestController
@RequestMapping("/work")
class AdminWorkController {
@Autowired
private lateinit var workService: UserWorkService
@PostMapping("/add")
fun addWork(@ModelAttribute request:ReqWork):ResponseEntity<*>{
val newWork = workService.addWork(request)
val respWork = RespWork(
newWork.userId,
newWork.materialType,
newWork.fIxWork,
)
return ResponseEntity(respWork,HttpStatus.OK)
}
}

我在服务类中得到空指针错误。默认值是多少?枚举类型

的值

Answer 1

您提供的堆栈跟踪显示，当尝试调用控制器时，异常实际上不会在服务类中发生，而是在Spring的机制中发生。

AdminWorkController.addWork接受request: ReqWork作为输入，因此spring必须将请求数据映射到ReqWork实例，这就是失败的原因。

失败意味着您的请求不包含fIxWork的值，因此您应该检查/add端点的调用者。很可能表单数据不包含fIxWork的值。

Answer 2

发生崩溃是因为val fIxWork被声明为非空类型FIxWork而不是空类型FIxWork?

请检查为什么UserWorkService从方法

返回fIxWork的null

fun addWork(request:ReqWork):UserWork

如果从上述方法中获得fIxWork的null是正常的，那么请将变量的声明修改为

val fIxWork: FIxWork?