如何解决bean 实例化失败；嵌套异常； SpringBoot 和 Vaadin
我要坦率地说，我是 Java 新手，尤其是 SpringBoot。我一直在模仿 Vaadin CRM 教程应用程序，并根据我的需要进行了轻微的定制。 当我尝试登录时，它抛出以下错误，我无法弄清楚，所以再次，我只是要复制粘贴整个堆栈跟踪：
尝试导航到 '' 时出现异常，并显示异常消息“在文件 [C:\Users\nikol\Desktop\vaadin-crm\vaadin-crm\target\ classes\com\vaadin\tutorial\crm\UI\views\list\ListView.class]：通过构造函数的 Bean 实例化失败；嵌套异常是 org.springframework.beans.BeanInstantiationException：无法实例化 [com.vaadin.tutorial.crm.UI.views.list.ListView]：构造函数抛出异常；嵌套异常是 java.lang.IllegalStateException：属性类型“java.lang.Integer”与字段类型“java.lang.String”不匹配。绑定应使用转换器手动配置。'
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'listView' defined in file [C:\Users\nikol\Desktop\vaadin-crm\vaadin-crm\target\classes\com\vaadin\tutorial\crm\UI\views\list\ListView.class]: Bean instantiation via constructor Failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.vaadin.tutorial.crm.UI.views.list.ListView]: Constructor threw exception; nested exception is java.lang.IllegalStateException: Property type 'java.lang.Integer' doesn't match the field type 'java.lang.String'. Binding should be configured manually using converter.
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:315)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:296)
at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.autowireConstructor(AbstractAutowireCapablebeanfactory.java:1354)
at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.createBeanInstance(AbstractAutowireCapablebeanfactory.java:1204)
at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.doCreateBean(AbstractAutowireCapablebeanfactory.java:564)
at org.springframework.beans.factory.support.AbstractAutowireCapablebeanfactory.createBean(AbstractAutowireCapablebeanfactory.java:524)
at org.springframework.beans.factory.support.Abstractbeanfactory.doGetBean(Abstractbeanfactory.java:353)
at org.springframework.beans.factory.support.Abstractbeanfactory.getBean(Abstractbeanfactory.java:233)
at org.springframework.beans.factory.support.DefaultListablebeanfactory.resolveNamedBean(DefaultListablebeanfactory.java:1273)
at org.springframework.beans.factory.support.DefaultListablebeanfactory.resolveNamedBean(DefaultListablebeanfactory.java:1234)
at org.springframework.beans.factory.support.DefaultListablebeanfactory.resolveBean(DefaultListablebeanfactory.java:494)
at org.springframework.beans.factory.support.DefaultListablebeanfactory.getBean(DefaultListablebeanfactory.java:349)
at org.springframework.beans.factory.support.DefaultListablebeanfactory.getBean(DefaultListablebeanfactory.java:342)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1172)
at com.vaadin.flow.spring.SpringInstantiator.getorCreate(SpringInstantiator.java:106)
at com.vaadin.flow.di.Instantiator.createRouteTarget(Instantiator.java:160)
at com.vaadin.flow.router.internal.AbstractNavigationStateRenderer.lambda$getRouteTarget$1(AbstractNavigationStateRenderer.java:137)
at java.base/java.util.Optional.orElseGet(Optional.java:362)
at com.vaadin.flow.router.internal.AbstractNavigationStateRenderer.getRouteTarget(AbstractNavigationStateRenderer.java:136)
at com.vaadin.flow.router.internal.AbstractNavigationStateRenderer.sendBeforeEnterEventAndPopulateChain(AbstractNavigationStateRenderer.java:525)
at com.vaadin.flow.router.internal.AbstractNavigationStateRenderer.createChainIfEmptyAndExecuteBeforeEnterNavigation(AbstractNavigationStateRenderer.java:505)
at com.vaadin.flow.router.internal.AbstractNavigationStateRenderer.handle(AbstractNavigationStateRenderer.java:222)
at com.vaadin.flow.router.Router.handleNavigation(Router.java:249)
at com.vaadin.flow.router.Router.navigate(Router.java:220)
at com.vaadin.flow.router.Router.navigate(Router.java:186)
at com.vaadin.flow.router.Router.initializeUI(Router.java:93)
at com.vaadin.flow.server.BootstrapHandler.initializeUIWithRouter(BootstrapHandler.java:1532)
at com.vaadin.flow.server.BootstrapHandler.createAndInitUI(BootstrapHandler.java:1525)
at com.vaadin.flow.server.BootstrapHandler.synchronizedHandleRequest(BootstrapHandler.java:475)
at com.vaadin.flow.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:40)
at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1547)
at com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:247)
at com.vaadin.flow.spring.SpringServlet.service(SpringServlet.java:111)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.apache.catalina.core.Applicationdispatcher.invoke(Applicationdispatcher.java:710)
at org.apache.catalina.core.Applicationdispatcher.processRequest(Applicationdispatcher.java:457)
at org.apache.catalina.core.Applicationdispatcher.doForward(Applicationdispatcher.java:352)
at org.apache.catalina.core.Applicationdispatcher.forward(Applicationdispatcher.java:312)
at org.springframework.web.servlet.mvc.ServletForwardingController.handleRequestInternal(ServletForwardingController.java:141)
at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:177)
at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:52)
at org.springframework.web.servlet.dispatcherServlet.dodispatch(dispatcherServlet.java:1060)
at org.springframework.web.servlet.dispatcherServlet.doService(dispatcherServlet.java:962)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
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$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$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$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:105)
at org.springframework.security.web.FilterChainProxy$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.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:218)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:212)
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:119)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:110)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:80)
at org.springframework.security.web.FilterChainProxy$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:119)
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:358)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1707)
at org.apache.tomcat.util.net.socketProcessorBase.run(SocketProcessorBase.java:49)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.vaadin.tutorial.crm.UI.views.list.ListView]: Constructor threw exception; nested exception is java.lang.IllegalStateException: Property type 'java.lang.Integer' doesn't match the field type 'java.lang.String'. Binding should be configured manually using converter.
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:225)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:117)
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:311)
... 120 more
Caused by: java.lang.IllegalStateException: Property type 'java.lang.Integer' doesn't match the field type 'java.lang.String'. Binding should be configured manually using converter.
at com.vaadin.flow.data.binder.Binder.bindProperty(Binder.java:2859)
at com.vaadin.flow.data.binder.Binder.lambda$null$26(Binder.java:2759)
at com.vaadin.flow.data.binder.Binder.handleProperty(Binder.java:2948)
at com.vaadin.flow.data.binder.Binder.lambda$bindInstanceFields$27(Binder.java:2757)
at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)
at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)
at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
at java.base/java.util.stream.AbstractPipeline.wrapAndcopyInto(AbstractPipeline.java:474)
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:563)
at com.vaadin.flow.data.binder.Binder.bindInstanceFields(Binder.java:2761)
at com.vaadin.tutorial.crm.UI.views.list.LivreForm.<init>(LivreForm.java:44)
at com.vaadin.tutorial.crm.UI.views.list.ListView.<init>(ListView.java:63)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:212)
... 122 more
stacktrace 中提到的 ListView 如下：
package com.vaadin.tutorial.crm.UI.views.list;
import com.vaadin.flow.component.Key;
import com.vaadin.flow.component.button.Button;
import com.vaadin.flow.component.button.ButtonVariant;
import com.vaadin.flow.component.dependency.CssImport;
import com.vaadin.flow.component.grid.Grid;
import com.vaadin.flow.component.html.Div;
import com.vaadin.flow.component.notification.Notification;
import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
import com.vaadin.flow.component.orderedlayout.VerticalLayout;
import com.vaadin.flow.component.textfield.TextField;
import com.vaadin.flow.data.value.ValueChangeMode;
import com.vaadin.flow.router.PageTitle;
import com.vaadin.flow.router.Route;
import com.vaadin.flow.server.PWA;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;
import com.vaadin.tutorial.crm.backend.entity.Campus;
import com.vaadin.tutorial.crm.backend.entity.Livre;
import com.vaadin.tutorial.crm.backend.entity.Stock;
import com.vaadin.tutorial.crm.backend.service.CampusService;
import com.vaadin.tutorial.crm.backend.service.LivreService;
import com.vaadin.tutorial.crm.UI.views.list.LivreForm;
import com.vaadin.tutorial.crm.UI.views.list.MainLayout;
/**
* A sample Vaadin view class.
* <p>
* To implement a Vaadin view just extend any Vaadin component and
* use @Route annotation to announce it in a URL as a Spring managed
* bean.
* Use the @PWA annotation make the application installable on phones,* tablets and some desktop browsers.
* <p>
* A new instance of this class is created for every new user and every
* browser tab/window.
*/
@Component
@Scope("prototype")
@Route(value = "",layout = MainLayout.class)
@PageTitle("Livres | ENI Ecole informatique")
public class ListView extends VerticalLayout {
LivreService livreService;
Grid<Livre> grid = new Grid<>(Livre.class);
TextField filterText = new TextField();
LivreForm form1;
public ListView(LivreService livreService,CampusService campusService) {
this.livreService = livreService;
addClassName("list-view");
setSizefull();
configureGrid();
form1 = new LivreForm(campusService.findAll());
form1.addListener(LivreForm.SaveEvent.class,this::saveLivre);
form1.addListener(LivreForm.DeleteEvent.class,this::deleteLivre);
form1.addListener(LivreForm.CloseEvent.class,e -> closeEditor());
add(grid);
add(filterText,grid,form1);
Div content = new Div(grid,form1);
content.addClassName("content");
content.setSizefull();
add(getToolbar(),content);
updateList();
closeEditor();
}
private void configureGrid() {
grid.addClassName("livre-grid");
grid.setSizefull();
grid.removeColumnByKey("campus");
grid.removeColumnByKey("stock");
grid.setColumns("titreLivre","description","auteur","refeni","isbn","categorie","status");
grid.addColumn(livre -> {
Campus campus = livre.getCampus();
return campus == null ? "-" : campus.getNomCampus();
}).setHeader("Campus");
grid.addColumn(livre -> {
Stock stock = livre.getStock();
return stock == null ? "-" : stock.getQuantiteStock();
}).setHeader("Stock");
grid.getColumns().forEach(col -> col.setAutoWidth(true));
grid.asSingleSelect().addValuechangelistener(event ->
editLivre(event.getValue()));
}
public void editLivre(Livre livre) {
if (livre == null) {
closeEditor();
} else {
form1.setLivre(livre);
form1.setVisible(true);
addClassName("editing");
}
}
private void saveLivre(LivreForm.SaveEvent event) {
livreService.save(event.getLivre());
updateList();
closeEditor();
}
private void deleteLivre(LivreForm.DeleteEvent event) {
livreService.delete(event.getLivre());
updateList();
closeEditor();
}
private void closeEditor() {
form1.setLivre(null);
form1.setVisible(false);
removeClassName("editing");
}
private HorizontalLayout getToolbar() {
filterText.setPlaceholder("Filtrer par titre ou auteur...");
filterText.setClearButtonVisible(true);
filterText.setValueChangeMode(ValueChangeMode.LAZY);
filterText.addValuechangelistener(e -> updateList());
Button addLivreButton = new Button("Ajouter livre");
addLivreButton.addClickListener(click -> addLivre());
HorizontalLayout toolbar = new HorizontalLayout(filterText,addLivreButton);
toolbar.addClassName("toolbar");
return toolbar;
}
void addLivre() {
grid.asSingleSelect().clear();
editLivre(new Livre());
}
private void updateList() {
grid.setItems(livreService.findAll(filterText.getValue()));
}
}
LivreForm 是这样的：
package com.vaadin.tutorial.crm.UI.views.list;
import com.vaadin.flow.component.Component;
import com.vaadin.flow.component.ComponentEvent;
import com.vaadin.flow.component.ComponentEventListener;
import com.vaadin.flow.component.Key;
import com.vaadin.flow.component.button.Button;
import com.vaadin.flow.component.button.ButtonVariant;
import com.vaadin.flow.component.comboBox.ComboBox;
import com.vaadin.flow.component.formlayout.Formlayout;
import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
import com.vaadin.flow.component.textfield.EmailField;
import com.vaadin.flow.component.textfield.TextField;
import com.vaadin.flow.data.binder.BeanValidationBinder;
import com.vaadin.flow.data.binder.Binder;
import com.vaadin.flow.data.binder.ValidationException;
import com.vaadin.flow.shared.Registration;
import com.vaadin.tutorial.crm.backend.entity.Livre;
import com.vaadin.tutorial.crm.backend.entity.Livre.Categorie;
import com.vaadin.tutorial.crm.backend.entity.Campus;
import com.vaadin.tutorial.crm.backend.entity.Stock;
import java.util.List;
public class LivreForm extends Formlayout{
TextField titreLivre = new TextField("titreLivre");
TextField description = new TextField("description");
TextField auteur = new TextField("auteur");
TextField refeni = new TextField("refeni");
TextField isbn = new TextField("isbn");
ComboBox<Livre.Categorie> categorie = new ComboBox<>("Categorie");
ComboBox<Livre.Status> status = new ComboBox<>("Status");
ComboBox<Stock> stock = new ComboBox<>("Stock");
ComboBox<Campus> campus = new ComboBox<>("Campus");
Button save = new Button("Save");
Button delete = new Button("Delete");
Button close = new Button("Cancel");
Binder<Livre> binder = new BeanValidationBinder<>(Livre.class);
private Livre livre;
public LivreForm(List<Campus> campuses) {
addClassName("livre-form");
binder.bindInstanceFields(this);
campus.setItems(campuses);
campus.setItemLabelGenerator(Campus::getNomCampus);
status.setItems(Livre.Status.values());
categorie.setItems(Livre.Categorie.values());
add(titreLivre,description,auteur,refeni,isbn,categorie,status,campus,stock,createButtonsLayout());
}
public void setLivre(Livre livre) {
this.livre = livre;
binder.readBean(livre);
}
private Component createButtonsLayout() {
save.addThemeVariants(ButtonVariant.LUMO_PRIMARY);
delete.addThemeVariants(ButtonVariant.LUMO_ERROR);
close.addThemeVariants(ButtonVariant.LUMO_TERTIARY);
save.addClickShortcut(Key.ENTER);
close.addClickShortcut(Key.ESCAPE);
save.addClickListener(event -> validateAndSave());
delete.addClickListener(event -> fireEvent(new DeleteEvent(this,livre)));
close.addClickListener(event -> fireEvent(new CloseEvent(this)));
binder.addStatuschangelistener(e -> save.setEnabled(binder.isValid()));
return new HorizontalLayout(save,delete,close);
}
private void validateAndSave() {
try {
binder.writeBean(livre);
fireEvent(new SaveEvent(this,livre));
} catch (ValidationException e) {
e.printstacktrace();
}
}
public static abstract class LivreFormEvent extends ComponentEvent<LivreForm> {
private Livre livre;
protected LivreFormEvent(LivreForm source,Livre contact) {
super(source,false);
this.livre = livre;
}
public Livre getLivre() {
return livre;
}
}
public static class SaveEvent extends LivreFormEvent {
SaveEvent(LivreForm source,Livre livre) {
super(source,livre);
}
}
public static class DeleteEvent extends LivreFormEvent {
DeleteEvent(LivreForm source,livre);
}
}
public static class CloseEvent extends LivreFormEvent {
CloseEvent(LivreForm source) {
super(source,null);
}
}
public <T extends ComponentEvent<?>> Registration addListener(Class<T> eventType,ComponentEventListener<T> listener) {
return getEventBus().addListener(eventType,listener);
}
}
希望你能告诉我第 63 行和第 44 行是如何相关的以及它们的问题是什么，因为这个特定的代码猴子被难住了。
解决方法
问题是当您尝试在第 62 行添加 form1 时未初始化它。
Caused by: java.lang.NullPointerException: Component to add cannot be null
at java.base/java.util.Objects.requireNonNull(Objects.java:233)
at com.vaadin.flow.component.HasComponents.add(HasComponents.java:53)
at com.vaadin.tutorial.crm.UI.views.list.ListView.<init>(ListView.java:62)
使用此链接，它提供了最佳解决方案https://vaadin.com/docs/v8/framework/datamodel/datamodel-forms#datamodel.forms.conversion
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