Java集合sort排序报错UnsupportedOperationException处理

文章目录

报错场景

我们使用的是PostgreSQL数据库，存储业务数据，业务代码使用的是Spring JPA
我们做的是智慧交通信控平台，有个功能是查询展示区域的交通态势，需要按照不同维度排序展示
区域态势指标计算，15分钟一次，每次计算存储所有区域指标。我们的实时态势展示，每次展示当前最新结果
业务要求，要按照区域交通流量、拥堵指数、拥堵里程分别倒序展示，写在了一个接口里，先查询后排序
我们使用的默认自增的主键策略，故获取最新一次区域态势结果，可以使用id倒序，按照区域数量获取
查询的业务逻辑比较简单，代码很快就写完了，使用JPA查询语句，构造查询和排序条件。得到查询结果list后，再根据业务需要，按照不同的字段排序
但在部署测试环境后发现，排序代码执行报错，报错 null Not Implemented
具体业务代码如下

java 复制代码

    /**
     * 获取所有区域实时态势
     * @param targetIndex 排序字段
     * @return 
     */
    public List<SituationAnalysisRegion> getCurrentRegionSituationList(String targetIndex) {
        // 获取所有子区
        List<SubRegion> allSubRegions = getAllSubRegion();
        Map<Integer, SubRegion> idSubRegionMap = new HashMap<>();
        allSubRegions.forEach(e -> idSubRegionMap.put(e.getId().intValue(), e));
        // 获取所有子区态势排名倒序
        Specification<SituationAnalysisRegion> specification = (root, query, cb)->{
            List<Predicate> predicates = new ArrayList<>();
            predicates.add(cb.greaterThan(root.get("timeStamp").as(Instant.class), LocalDateTime.now().plusMinutes(-15).plusSeconds(-30).atZone(ZoneId.systemDefault()).toInstant()));
            Predicate[] pre = new Predicate[predicates.size()];
            pre = predicates.toArray(pre);
            return query.where(pre).getRestriction();
        };
        Sort orders = Sort.by("id").descending();
        Pageable pageable = PageRequest.of(0, allSubRegions.size(), orders);
        List<SituationAnalysisRegion> situationAnalysisRegions = analysisRegionRepository.findAll(specification, pageable).getContent();
        // 排序要求
        if (null == targetIndex || StringUtils.isEmpty(targetIndex)) {
            situationAnalysisRegions.sort((o1, o2) -> (int)(o2.getCongestionMileage() - o1.getCongestionMileage()));
        } else if (targetIndex.equals("trafficFlow")) {
            situationAnalysisRegions.sort((o1, o2) -> o2.getTrafficFlow() - o1.getTrafficFlow());
        } else if (targetIndex.equals("congestionIndex")) {
            situationAnalysisRegions.sort((o1, o2) -> (int)(o2.getCongestionIndex() - o1.getCongestionIndex()));
        } else {
            situationAnalysisRegions.sort((o1, o2) -> (int)(o2.getCongestionMileage() - o1.getCongestionMileage()));
        }
        return situationAnalysisRegions;
    }

具体报错日志如下：

2023-08-29 16:12:56.168 ERROR 12860 --- [ XNIO-1 task-1] o.z.problem.spring.common.AdviceTraits : Not Implemented

java.lang.UnsupportedOperationException: null
at java.base/java.util.CollectionsFilterChainImpl.doFilter(FilterHandler.java:129)
at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:91)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet.handlers.FilterHandler $FilterChainImpl.doFilter(FilterHandler.java:131) at com.newatc.api.redis.RequestFilter.doFilter(RequestFilter.java:58) at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) at io.undertow.servlet.handlers.FilterHandler$ FilterChainImpl.doFilter(FilterHandler.java:131)
at org.springframework.security.web.FilterChainProxy $VirtualFilterChain.doFilter(FilterChainProxy.java:327) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81) at org.springframework.security.web.FilterChainProxy$ VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:122)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:116)
at org.springframework.security.web.FilterChainProxy $VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81) at org.springframework.security.web.FilterChainProxy$ VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.oauth2.client.web.OAuth2AuthorizationCodeGrantFilter.doFilterInternal(OAuth2AuthorizationCodeGrantFilter.java:168)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.springframework.security.web.FilterChainProxy $VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:109) at org.springframework.security.web.FilterChainProxy$ VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149)
at org.springframework.security.web.FilterChainProxy $VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) at org.springframework.security.web.FilterChainProxy$ VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.oauth2.server.resource.web.BearerTokenAuthenticationFilter.doFilterInternal(BearerTokenAuthenticationFilter.java:125)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.springframework.security.web.FilterChainProxy $VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.oauth2.client.web.OAuth2AuthorizationRequestRedirectFilter.doFilterInternal(OAuth2AuthorizationRequestRedirectFilter.java:178) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.springframework.security.web.FilterChainProxy$ VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:103)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:89)
at org.springframework.security.web.FilterChainProxy $VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90) at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.springframework.security.web.FilterChainProxy$ VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:112)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:82)
at org.springframework.security.web.FilterChainProxy $VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:55) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at org.springframework.security.web.FilterChainProxy$ VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.web.session.DisableEncodeUrlFilter.doFilterInternal(DisableEncodeUrlFilter.java:42)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.springframework.security.web.FilterChainProxy $VirtualFilterChain.doFilter(FilterChainProxy.java:336) at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:211) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:183) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:354) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:267) at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) at io.undertow.servlet.handlers.FilterHandler$ FilterChainImpl.doFilter(FilterHandler.java:131)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet.handlers.FilterHandler $FilterChainImpl.doFilter(FilterHandler.java:131) at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) at io.undertow.servlet.handlers.FilterHandler$ FilterChainImpl.doFilter(FilterHandler.java:131)
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:96)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet.handlers.FilterHandler $FilterChainImpl.doFilter(FilterHandler.java:131) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) at io.undertow.servlet.handlers.FilterHandler$ FilterChainImpl.doFilter(FilterHandler.java:131)
at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:68)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at io.undertow.servlet.handlers.RedirectDirHandler.handleRequest(RedirectDirHandler.java:68)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:117)
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.SendErrorPageHandler.handleRequest(SendErrorPageHandler.java:52)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.SessionRestoringHandler.handleRequest(SessionRestoringHandler.java:119)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:275)
at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:79)
at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:134)
at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:131)
at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:255)
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:79)
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:100)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:387)
at io.undertow.server.HttpServerExchange $1.run(HttpServerExchange.java:852) at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35) at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:2019) at org.jboss.threads.EnhancedQueueExecutor$ ThreadBody.doRunTask(EnhancedQueueExecutor.java:1558)
at org.jboss.threads.EnhancedQueueExecutor $ThreadBody.run(EnhancedQueueExecutor.java:1449) at org.xnio.XnioWorker$ WorkerThreadFactory$1$1.run(XnioWorker.java:1282)
at java.base/java.lang.Thread.run(Thread.java:834)

2023-08-29 16:12:56.227 WARN 12860 --- [ XNIO-1 task-1] .m.m.a.ExceptionHandlerExceptionResolver : Resolved [java.lang.UnsupportedOperationException]

排查解决

日志核心打印：Not Implemented、 java.lang.UnsupportedOperationException: null、at java.base/java.util.Collections$UnmodifiableList.sort(Collections.java:1332)
一开始看着报错null，以为是空指针异常，想着是不是没查询到数据，或者排序字段的值有null值
查看了数据库数据，发现没问题，只好本地debug排查
加了断点，进行debug，确认返回结果list有值，且排序字段也都有值，继续执行，还是这个报错
想着要进行更细粒度的debug，于是按着 F5 继续调试，结果发现，也是直接一步走进报错，在这一行（Collections.sort）
一下子没法排查了，这个报错之前也没注意过，于是继续去网上搜索相应报错，还真找到了
还是要回到报错日志，核心是这一句：at java.base/java.util.Collections$UnmodifiableList.sort(Collections.java:1332)
在执行Collections.sort()方法时，发现传入的集合list，是一个不可修改的UnmodifiableList.，不能直接拿来排序
但是可以通过新建一个list，来解决这个问题

java 复制代码

        List<SituationAnalysisRegion> situationAnalysisRegions = analysisRegionRepository.findAll(specification, pageable).getContent();
        // 重新赋值，排除 UnmodifiableList 报错
        List<SituationAnalysisRegion> result = new ArrayList<>(situationAnalysisRegions);
        // 排序要求
        if (null == targetIndex || StringUtils.isEmpty(targetIndex)) {
            result.sort((o1, o2) -> (int)(o2.getCongestionMileage() - o1.getCongestionMileage()));
        } else if (targetIndex.equals("trafficFlow")) {
            result.sort((o1, o2) -> o2.getTrafficFlow() - o1.getTrafficFlow());
        } else if (targetIndex.equals("congestionIndex")) {
            result.sort((o1, o2) -> (int)(o2.getCongestionIndex() - o1.getCongestionIndex()));
        } else {
            result.sort((o1, o2) -> (int)(o2.getCongestionMileage() - o1.getCongestionMileage()));
        }
        return result;

现在问题很明确了，JPA的查询代码，返回的list，是个不可修改的list。在网上查询该问题时，发现其他的一些类似查询，也可能返回一个不可修改的list，如 MongoDB的Java查询语句
以后如果看到Collections$UnmodifiableList.sort报错，就要考虑到这种情况，都可以类似处理

UnmodifiableList类介绍

UnmodifiableList类是Collections的内部类
Java的Collections框架提供了UnmodifiableList类作为不可变列表的一种实现
UnmodifiableList实现了List接口，但是在其基础上增加了一些限制，例如不允许修改列表中的元素、不允许添加新元素以及不允许删除已有元素。因此，可以使用UnmodifiableList来保护某些关键数据，防止其他程序修改它们
使用方式非常简单，通过Collections.unmodifiableList(List list)方法可以将一个可变的列表转换为一个不可变的列表，例如：

List<String> mutableList = new ArrayList<>();
mutableList.add("apple");
mutableList.add("banana");
mutableList.add("orange");

List<String> immutableList = Collections.unmodifiableList(mutableList);
这样，immutableList就成为了一个不可变的列表，任何尝试修改、添加或删除其中的元素的操作都会抛出UnsupportedOperationException异常。