【发布时间】：2022-08-20 19:51:26
【问题描述】：
我一直得到异常NullPointerException: bean cannot be null。
我使用服务并在本地有一个 mongoDB。我可以从中得到信息。但是如果我想按下按钮来添加我的输入，我会得到这个 NullPointerException。
我的 pom 还指的是我的依赖项的最新版本。
我怎样才能避免这个异常？
@Route(value = \"adddevice\", layout = MainLayout.class)
@RolesAllowed({\"ADMIN\", \"USER\"})
public class NewDeviceView extends VerticalLayout {
NewDeviceForm form;
DeviceService service;
public NewDeviceView(DeviceService service){
this.service=service;
form = new NewDeviceForm();
form.addListener(NewDeviceForm.SaveEvent.class, this::saveDevice);
configureForm();
add(getContent());
}
private HorizontalLayout getContent() {
HorizontalLayout content = new HorizontalLayout(form);
content.setFlexGrow(2);
content.setFlexGrow(1, form);
content.addClassNames(\"content\");
content.setSizeFull();
return content;
}
private void configureForm() {
form = new NewDeviceForm();
form.addListener(NewDeviceForm.SaveEvent.class, this::saveDevice);
}
private void saveDevice(NewDeviceForm.SaveEvent event) {
service.saveDevice(event.getDevice());
}
} ```
```public class NewDeviceForm extends FormLayout {
private Device device;
TextField alias = new TextField(\"Alias Hinzufügen\");
TextField aetit = new TextField(\"AET Hinzufügen\");
TextField ipAdress = new TextField(\"IPAdress Hinzufügen\");
TextField port = new TextField(\"Port Hinzufügen\");
TextField incomingDirectory = new TextField(\"Eingangsverzeichnis Hinzufügen\");
Binder<Device> binder = new BeanValidationBinder<>(Device.class);
Button addButton = new Button(\"Hinzufügen\");
Button backButton = new Button(\"Back\");
public NewDeviceForm(){
binder.bindInstanceFields(this);
add(
alias,
aetit,
ipAdress,
port,
incomingDirectory,
createButtonsLayout()
);
}
private Component createButtonsLayout() {
addButton.addClickShortcut(Key.ENTER);
addButton.addClickListener(event -> validateAndSave());
binder.addStatusChangeListener(e -> addButton.setEnabled(binder.isValid()));
return new HorizontalLayout(addButton,backButton);
}
public void validateAndSave(){
try {
binder.writeBean(device);
fireEvent(new SaveEvent(this, device));
} catch (ValidationException e){
e.printStackTrace();
}
}
public void setDevice(Device device){
this.device = device;
binder.readBean(device);
}
public static abstract class NewDeviceFormEvent extends ComponentEvent<NewDeviceForm> {
private Device device;
protected NewDeviceFormEvent(NewDeviceForm source, Device device){
super(source,false);
this.device=device;
}
public Device getDevice(){
return device;
}
}
public static class SaveEvent extends NewDeviceFormEvent {
SaveEvent(NewDeviceForm source, Device device){
super(source,device);
}
}
public <T extends ComponentEvent<?>> Registration addListener(
Class<T> eventType, ComponentEventListener<T> listener){
return getEventBus().addListener(eventType, listener);
}
}```
java.lang.NullPointerException: bean cannot be null
at java.base/java.util.Objects.requireNonNull(Objects.java:233) ~[na:na]
at com.vaadin.flow.data.binder.Binder.doWriteIfValid(Binder.java:2280) ~[flow-data-23.1.3.jar:23.1.3]
at com.vaadin.flow.data.binder.Binder.writeBean(Binder.java:2194) ~[flow-data-23.1.3.jar:23.1.3]
at com.example.application.form.NewDeviceForm.validateAndSave(NewDeviceForm.java:59) ~[classes/:na]
at com.example.application.form.NewDeviceForm.lambda$createButtonsLayout$b71f5360$1(NewDeviceForm.java:50) ~[classes/:na]
at com.vaadin.flow.component.ComponentEventBus.fireEventForListener(ComponentEventBus.java:206) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.component.ComponentEventBus.handleDomEvent(ComponentEventBus.java:448) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.component.ComponentEventBus.lambda$addDomTrigger$dd1b7957$1(ComponentEventBus.java:265) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.internal.nodefeature.ElementListenerMap.lambda$fireEvent$2(ElementListenerMap.java:447) ~[flow-server-23.1.3.jar:23.1.3]
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) ~[na:na]
at com.vaadin.flow.internal.nodefeature.ElementListenerMap.fireEvent(ElementListenerMap.java:447) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.communication.rpc.EventRpcHandler.handleNode(EventRpcHandler.java:62) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.communication.rpc.AbstractRpcInvocationHandler.handle(AbstractRpcInvocationHandler.java:75) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.communication.ServerRpcHandler.handleInvocationData(ServerRpcHandler.java:438) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.communication.ServerRpcHandler.lambda$handleInvocations$1(ServerRpcHandler.java:419) ~[flow-server-23.1.3.jar:23.1.3]
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) ~[na:na]
at com.vaadin.flow.server.communication.ServerRpcHandler.handleInvocations(ServerRpcHandler.java:419) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:320) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:115) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:40) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1564) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:299) ~[flow-server-23.1.3.jar:23.1.3]
at com.vaadin.flow.spring.SpringServlet.service(SpringServlet.java:109) ~[vaadin-spring-23.1.3.jar:na]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.64.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:711) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:353) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:313) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.springframework.web.servlet.mvc.ServletForwardingController.handleRequestInternal(ServletForwardingController.java:141) ~[spring-webmvc-5.3.21.jar:5.3.21]
at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:177) ~[spring-webmvc-5.3.21.jar:5.3.21]
at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:51) ~[spring-webmvc-5.3.21.jar:5.3.21]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.21.jar:5.3.21]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.21.jar:5.3.21]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.21.jar:5.3.21]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.3.21.jar:5.3.21]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:681) ~[tomcat-embed-core-9.0.64.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.21.jar:5.3.21]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.64.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:327) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:122) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:116) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:109) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:223) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:217) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:103) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:89) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:117) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:112) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:82) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:55) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.session.DisableEncodeUrlFilter.doFilterInternal(DisableEncodeUrlFilter.java:42) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:211) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:183) ~[spring-security-web-5.7.2.jar:5.7.2]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:354) ~[spring-web-5.3.21.jar:5.3.21]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:267) ~[spring-web-5.3.21.jar:5.3.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.21.jar:5.3.21]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.21.jar:5.3.21]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.21.jar:5.3.21]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1787) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
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错误信息非常清楚。 validateAndSave 中的设备为空。你调试过你的代码吗？
-
是的，并且是空的。但我是盲人，不明白为什么会这样。
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我也没有看到。你能分享你的代码吗？
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在您填写表单之前，您的表单是否可以尝试保存它？如您所见，设备是在 setDevice 方法中设置的。因此，如果默认启用保存按钮，您可以单击它并在 device == null 时保存。试试下面的。默认情况下禁用保存按钮并在 setDevice 中启用它。怎么了？
标签： vaadin