java.lang.ClassCastException: java.util.ArrayList 不能转换为 java.lang.String
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时间：2020-11-02 09:57:03 来源:igfitidea点击:
java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String
提问by u12345
when I am running this code its giving me exception java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String on q1.list();
当我运行这段代码时，它给了我异常 java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String on q1.list();
Query q=session.createQuery("select categoryData FROM SearchHistoryEntity where userId=:u");
q.setInteger("u", userId);
List<String> list1=q.list();
if(list1!=null){
Query q1=session.createQuery("FROM BookEntity where category in (:names) order by bookId");
q1.setParameter("names", list1);
if(q1.list().size()>9){
q1.setFirstResult(1);
q1.setMaxResults(9);
}
list=new ArrayList<BookEntity>();
list=q1.list();
this is the full stacktrace:
这是完整的堆栈跟踪：
SEVERE: Servlet.service() for servlet [dispatcher] in context with path [/BookStore] threw exception [Request processing failed; nested exception is java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String] with root cause
java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String
at org.hibernate.type.descriptor.java.StringTypeDescriptor.unwrap(StringTypeDescriptor.java:39)
at org.hibernate.type.descriptor.sql.VarcharTypeDescriptor.doBind(VarcharTypeDescriptor.java:64)
at org.hibernate.type.descriptor.sql.BasicBinder.bind(BasicBinder.java:90)
at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:286)
at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:281)
at org.hibernate.param.NamedParameterSpecification.bind(NamedParameterSpecification.java:67)
at org.hibernate.loader.hql.QueryLoader.bindParameterValues(QueryLoader.java:613)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1900)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1861)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1838)
at org.hibernate.loader.Loader.doQuery(Loader.java:909)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:354)
at org.hibernate.loader.Loader.doList(Loader.java:2553)
at org.hibernate.loader.Loader.doList(Loader.java:2539)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2369)
at org.hibernate.loader.Loader.list(Loader.java:2364)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:496)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:387)
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:231)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1264)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:103)
at com.app.dao.hib.SearchHistoryDaoImpl.categoryData(SearchHistoryDaoImpl.java:150)
at com.app.service.impl.SearchHistoryServiceImpl.recommend(SearchHistoryServiceImpl.java:62)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.transaction.interceptor.TransactionInterceptor.proceedWithInvocation(TransactionInterceptor.java:98)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:262)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
at $Proxy37.recommend(Unknown Source)
at com.app.controller.UserController.recommend(UserController.java:74)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
I the above code i am just trying to get the list of titles from SearchHistory table corresponding to a particular userId (which is query q) and then finding the list of books with those titles (query q1) but there is some problem its not working. can anyone help me with this
我上面的代码只是想从 SearchHistory 表中获取与特定 userId 相对应的标题列表（即查询 q），然后找到具有这些标题的书籍列表（查询 q1），但存在一些问题，它不起作用. 谁能帮我这个
回答by Tom Chamberlain
Try changing
尝试改变
q1.setParameter("names", list1);
to
到
q1.setParameterList("names", list1);
回答by Aakash Gandhi
try like this
像这样尝试
List<String> list1= new ArrayList<String>();
list.add(q);
回答by Chirag Patel
try this:
试试这个：
For emaple we have pass data on server through api url and we pass parameter or body
parameter value same process is here. we will pass list in parameter in this case:
q1.setParameterList("names", list1);
回答by Chirag Patel
q1.setParameterList("names", list1);
