获取 spring 引导异常：java.lang.ClassCastException：class [Ljava.lang.Object；无法转换为 class
Getting spring boot Exception: java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class
我得到 java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class。无法理解此错误的根本原因以及解决方法。
这是我的查询代码：
Query query3 = manager.createNativeQuery
("SELECT * from trasactiondetail"
+ " WHERE orgidinsidercode = :orgid AND"
+ " shopkeeperid != :shopKeeperId "
+ " AND DATE_FORMAT(trasactiondetail.date, '%Y-%m') = :attendanceDateToRetrieve \n"
+" AND trasactiondetail.clientrole='Employee' GROUP BY clientmobno"
+ " ");
query3.setParameter("attendanceDateToRetrieve", attendanceDateToRetrieve);
query3.setParameter("shopKeeperId", shopKeeperId);
query3.setParameter("orgid", orgid);
@SuppressWarnings("unchecked")
List<Trasactiondetail> empWhoScannedMyQRCodeButNotMyEmployee = query3.getResultList();
显示 arraylist 中的值的代码：（列表中存在 2 个元素）
for(int i=0;i<empWhoScannedMyQRCodeButNotMyEmployee.size();i++) {
String EmployeeMob = empWhoScannedMyQRCodeButNotMyEmployee.get(i).getClientmobno();
System.out.println("empWhoScannedMyQRCodeButNotMyEmployee empName: "+ empName);
}
在 String EmployeeMob = empWhoScannedMyQRCodeButNotMyEmployee.get(i).getClientmobno(); 处出现以下错误：
java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class com.sloth.generated.model.Trasactiondetail ([Ljava.lang.Object; is in module java.base of loader 'bootstrap'; com.sloth.generated.model.Trasactiondetail is in unnamed module of loader 'app')
at com.sloth.generated.controller.webpage.MonthlyAttendancePageController.monthlyattendancedetails(MonthlyAttendancePageController.java:949) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1064) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.9.jar:5.3.9]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.52.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.9.jar:5.3.9]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.52.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.9.jar:5.3.9]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.9.jar:5.3.9]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.9.jar:5.3.9]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1726) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]
当您调用 manager.createNativeQuery("SQL code") 时，此方法不知道它应该将每一行从 DB 映射到 Trasactiondetail 对象。因此，当您将列表从 getResultList() 转换为 List<Trasactiondetail> - 它不会起作用，因为结果列表包含另一种类型的对象（更具体地说，它是 List<Object[]> 所以它显然不能转换为您的类型）。
改用 manager.createNativeQuery("SQL code", Trasactiondetail.class)，它应该将结果映射到此 class，因此 getResultList 将 return 按您的预期更正列表。
我可以推荐你在这里阅读更多相关信息：https://thorben-janssen.com/jpa-native-queries/
我得到 java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class。无法理解此错误的根本原因以及解决方法。
这是我的查询代码：
Query query3 = manager.createNativeQuery
("SELECT * from trasactiondetail"
+ " WHERE orgidinsidercode = :orgid AND"
+ " shopkeeperid != :shopKeeperId "
+ " AND DATE_FORMAT(trasactiondetail.date, '%Y-%m') = :attendanceDateToRetrieve \n"
+" AND trasactiondetail.clientrole='Employee' GROUP BY clientmobno"
+ " ");
query3.setParameter("attendanceDateToRetrieve", attendanceDateToRetrieve);
query3.setParameter("shopKeeperId", shopKeeperId);
query3.setParameter("orgid", orgid);
@SuppressWarnings("unchecked")
List<Trasactiondetail> empWhoScannedMyQRCodeButNotMyEmployee = query3.getResultList();
显示 arraylist 中的值的代码：（列表中存在 2 个元素）
for(int i=0;i<empWhoScannedMyQRCodeButNotMyEmployee.size();i++) {
String EmployeeMob = empWhoScannedMyQRCodeButNotMyEmployee.get(i).getClientmobno();
System.out.println("empWhoScannedMyQRCodeButNotMyEmployee empName: "+ empName);
}
在 String EmployeeMob = empWhoScannedMyQRCodeButNotMyEmployee.get(i).getClientmobno(); 处出现以下错误：
java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class com.sloth.generated.model.Trasactiondetail ([Ljava.lang.Object; is in module java.base of loader 'bootstrap'; com.sloth.generated.model.Trasactiondetail is in unnamed module of loader 'app')
at com.sloth.generated.controller.webpage.MonthlyAttendancePageController.monthlyattendancedetails(MonthlyAttendancePageController.java:949) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1064) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.9.jar:5.3.9]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.9.jar:5.3.9]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.52.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.9.jar:5.3.9]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.52.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.9.jar:5.3.9]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.9.jar:5.3.9]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.9.jar:5.3.9]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.9.jar:5.3.9]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1726) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.52.jar:9.0.52]
at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]
当您调用 manager.createNativeQuery("SQL code") 时，此方法不知道它应该将每一行从 DB 映射到 Trasactiondetail 对象。因此，当您将列表从 getResultList() 转换为 List<Trasactiondetail> - 它不会起作用，因为结果列表包含另一种类型的对象（更具体地说，它是 List<Object[]> 所以它显然不能转换为您的类型）。
改用 manager.createNativeQuery("SQL code", Trasactiondetail.class)，它应该将结果映射到此 class，因此 getResultList 将 return 按您的预期更正列表。
我可以推荐你在这里阅读更多相关信息：https://thorben-janssen.com/jpa-native-queries/