可选的 orElseGet 方法 returns ArrayList 而不是 Set
Optional orElseGet method returns ArrayList rather then Set
以下代码抛出：
ClassCastException: java.util.ArrayList cannot be cast to java.util.Set`
Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
.orElseGet(TreeSet::new);
方法 findByEmailAndSistemaAndPerfil returns 在 Set 和 Optional 中正确地处理了两个 Atuacao 类型的项目。为什么 orElseGet 方法返回 ArrayList？
我正在使用 Spring Data Jpa。
已添加：
方法findByEmailAndSistemaAndPerfil定义：
public Optional<Set<Atuacao>> findByEmailAndSistemaAndPerfil(
@Param("email") String email, @Param("idSistema") long idSistema);
已添加：
完整堆栈跟踪：
java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.util.Set
at br.mp.mpf.autoriza.service.AtuacaoService.findAtuacoes(AtuacaoService.java:30) ~[classes/:na]
at br.mp.mpf.autoriza.service.AtuacaoService$$FastClassBySpringCGLIB$bced465.invoke(<generated>) ~[classes/:na]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:769) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:353) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at br.mp.mpf.autoriza.service.AtuacaoService$$EnhancerBySpringCGLIB$1ace5.findAtuacoes(<generated>) ~[classes/:na]
at br.mp.mpf.seguranca.SecurityConfiguration.lambda[=13=](SecurityConfiguration.java:123) ~[classes/:na]
at org.springframework.security.oauth2.client.authentication.OAuth2LoginAuthenticationProvider.authenticate(OAuth2LoginAuthenticationProvider.java:120) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:175) ~[spring-security-core-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.oauth2.client.web.OAuth2LoginAuthenticationFilter.attemptAuthentication(OAuth2LoginAuthenticationFilter.java:185) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:212) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.oauth2.client.web.OAuth2AuthorizationRequestRedirectFilter.doFilterInternal(OAuth2AuthorizationRequestRedirectFilter.java:160) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:117) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1579) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.27.jar:9.0.27]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_201]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_201]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.27.jar:9.0.27]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_201]
方法findByEmailAndSistemaAndPerfil可能return是Optional<ArrayLIst<Atuacao>>所以没办法returnSet
如果你使用Java11，你可以将Optional转换为Stream并利用其收集器的优势：
Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
.stream()
.flatMap(List::stream)
.collect(Collectors.toCollection(TreeSet::new));
如果您坚持使用 Java 8，则将 ArrayList 换成 TreeSet:
new TreeSet<>(
findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
.orElse(new ArrayList<>()));
要么 'Atuacao' 必须实现 Comparable，要么您需要在创建 TreeSet 时提供比较器。
如SortedList所述。
All elements inserted into a sorted set must implement the Comparable
interface (or be accepted by the specified comparator). Furthermore,
all such elements must be mutually comparable: e1.compareTo(e2) (or
comparator.compare(e1, e2)) must not throw a ClassCastException for
any elements e1 and e2 in the sorted set. Attempts to violate this
restriction will cause the offending method or constructor invocation
to throw a ClassCastException
另一种选择是使用如下哈希集。
Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
.orElseGet(HashSet::new);
解决方案结合了@PattySpringDev 和@m-deinum 的想法。
- findBy 方法现在仅返回 Set；
- class
Atuacao 现在实现了 Comparable （在另一段代码中有一个比较器，已删除）；
最终代码为：
public Set<Atuacao> findByEmailAndSistemaAndPerfil(@Param("email") String email, @Param("idSistema") long idSistema);
Set<Atuacao> a = Optional.of(atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)).orElse(new TreeSet<Atuacao>());
以下代码抛出：
ClassCastException: java.util.ArrayList cannot be cast to java.util.Set`
Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
.orElseGet(TreeSet::new);
方法 findByEmailAndSistemaAndPerfil returns 在 Set 和 Optional 中正确地处理了两个 Atuacao 类型的项目。为什么 orElseGet 方法返回 ArrayList？
我正在使用 Spring Data Jpa。
已添加：
方法findByEmailAndSistemaAndPerfil定义：
public Optional<Set<Atuacao>> findByEmailAndSistemaAndPerfil(
@Param("email") String email, @Param("idSistema") long idSistema);
已添加：
完整堆栈跟踪：
java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.util.Set
at br.mp.mpf.autoriza.service.AtuacaoService.findAtuacoes(AtuacaoService.java:30) ~[classes/:na]
at br.mp.mpf.autoriza.service.AtuacaoService$$FastClassBySpringCGLIB$bced465.invoke(<generated>) ~[classes/:na]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:769) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:353) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at br.mp.mpf.autoriza.service.AtuacaoService$$EnhancerBySpringCGLIB$1ace5.findAtuacoes(<generated>) ~[classes/:na]
at br.mp.mpf.seguranca.SecurityConfiguration.lambda[=13=](SecurityConfiguration.java:123) ~[classes/:na]
at org.springframework.security.oauth2.client.authentication.OAuth2LoginAuthenticationProvider.authenticate(OAuth2LoginAuthenticationProvider.java:120) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:175) ~[spring-security-core-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.oauth2.client.web.OAuth2LoginAuthenticationFilter.attemptAuthentication(OAuth2LoginAuthenticationFilter.java:185) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:212) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.oauth2.client.web.OAuth2AuthorizationRequestRedirectFilter.doFilterInternal(OAuth2AuthorizationRequestRedirectFilter.java:160) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:117) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1579) [tomcat-embed-core-9.0.27.jar:9.0.27]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.27.jar:9.0.27]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_201]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_201]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.27.jar:9.0.27]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_201]
方法findByEmailAndSistemaAndPerfil可能return是Optional<ArrayLIst<Atuacao>>所以没办法returnSet
如果你使用Java11，你可以将Optional转换为Stream并利用其收集器的优势：
Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
.stream()
.flatMap(List::stream)
.collect(Collectors.toCollection(TreeSet::new));
如果您坚持使用 Java 8，则将 ArrayList 换成 TreeSet:
new TreeSet<>(
findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
.orElse(new ArrayList<>()));
要么 'Atuacao' 必须实现 Comparable，要么您需要在创建 TreeSet 时提供比较器。
如SortedList所述。
All elements inserted into a sorted set must implement the Comparable interface (or be accepted by the specified comparator). Furthermore, all such elements must be mutually comparable: e1.compareTo(e2) (or comparator.compare(e1, e2)) must not throw a ClassCastException for any elements e1 and e2 in the sorted set. Attempts to violate this restriction will cause the offending method or constructor invocation to throw a ClassCastException
另一种选择是使用如下哈希集。
Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
.orElseGet(HashSet::new);
解决方案结合了@PattySpringDev 和@m-deinum 的想法。
- findBy 方法现在仅返回 Set；
- class
Atuacao现在实现了Comparable（在另一段代码中有一个比较器，已删除）；
最终代码为：
public Set<Atuacao> findByEmailAndSistemaAndPerfil(@Param("email") String email, @Param("idSistema") long idSistema);
Set<Atuacao> a = Optional.of(atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)).orElse(new TreeSet<Atuacao>());