我是 java 新手，我正在运行本地服务器（jar）并尝试访问 API 端点。所有数据都是正确的，我得到以下信息：
java.util.NoSuchElementException：不存在值
执行似乎发生在代码片段的下面一行
。得到（）
任何帮助是极大的赞赏！！
使用java8
final List<BundleValue> existingBundleValues = bundles.stream()
.filter(bundle -> bundle.type().equals(bundleType))
.findFirst()
.get()
.values()
.stream()
.map(BundleValue::convertFromAbstractBundleValue)
.collect(Collectors.toList());
java.util.NoSuchElementException: No value present
at java.util.Optional.get(Optional.java:135)
at com.groupon.goods.productbundlingservice.service.BundlingService.isNewBundle(BundlingService.java:105)
at com.groupon.goods.productbundlingservice.resources.ProductBundlingServiceResource.createBundle(ProductBundlingServiceResource.java:119)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:160)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
at io.dropwizard.jetty.NonblockingServletHolder.handle(NonblockingServletHolder.java:49)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
at io.dropwizard.servlets.ThreadNameFilter.doFilter(ThreadNameFilter.java:34)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at io.dropwizard.jersey.filter.AllowedMethodsFilter.handle(AllowedMethodsFilter.java:45)
at io.dropwizard.jersey.filter.AllowedMethodsFilter.doFilter(AllowedMethodsFilter.java:39)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at com.groupon.jtier.bundles.ctx.CtxFilter.doFilter(CtxFilter.java:56)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at com.groupon.jtier.bundles.debug.StenoLoggerFilter.doFilter(StenoLoggerFilter.java:118)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at com.groupon.jtier.bundles.debug.RequestServletFilter.doFilter(RequestServletFilter.java:46)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533)
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
at com.codahale.metrics.jetty9.InstrumentedHandler.handle(InstrumentedHandler.java:241)
at io.dropwizard.jetty.RoutingHandler.handle(RoutingHandler.java:52)
at org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:455)
at io.dropwizard.jetty.BiDiGzipHandler.handle(BiDiGzipHandler.java:68)
at org.eclipse.jetty.server.handler.StatisticsHandler.handle(StatisticsHandler.java:169)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
at org.eclipse.jetty.server.Server.handle(Server.java:561)
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:334)
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:104)
at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:679)
at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:597)
at java.lang.Thread.run(Thread.java:748)
firstFirst返回一个Optional，你称之为get上，如果这是一个empty可选 - 您将得到该异常。
您可以按如下方式编写它，如果它存在（即Optional）你会把它映射到Map::values（我假设你的findFirst返回某种 aMap），否则得到Collections.emptyList().
bundles.stream()
.filter(bundle -> bundle.type().equals(bundleType))
.findFirst()
.map(Map::values)
.orElse(Collections.emptyList())
.stream()
.map(BundleValue::convertFromAbstractBundleValue)
.collect(Collectors.toList());
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