我有一个复选框和下拉列表在一个html页面。单击submit（提交）时，如果同时选中了这两个字段，则会显示一条错误消息，其中任何一个字段都应为必填字段，并要求至少选择一个值。
我创建了一个新类作为formvalidator实现ivalidator并重写validate方法。但我不知道如何使用下拉选择值和复选框值提交方法调用广告如何显示在html中。
java代码-

IModel<Project> dropdownModel =   new PropertyModel<Project>(criteria,"selectedBillableProject");
        DropDownChoice<Project> billableProjectsList = new DropDownChoice<>(
                "projectsList",
                dropdownModel,
                billableProjects,
                new ChoiceRenderer<Project>("fullNameWithCustomer"));
        billableProjectsList.setLabel(new ResourceModel("printMonth.billable"));

        form.add(billableProjectsList);

}

protected void onSubmit() {
           .....
            validateInputComponents(reportCriteria);
.....
}

public void validateInputComponents(ReportCriteria reportCriteria){

          add(new FormComponentValidator(reportCriteria.getSelectedBillableProject(), unbillableProjectsView.getModelObject()));      

        }

我已将FormComponentValidTo更新为类似于：https://cwiki.apache.org/confluence/display/wicket/validating+related+fields
但它会导致以下错误onsubmit（）。11-26@22：37:25 error org.apache.wicket.request.cycle.requestcycle-处理错误消息java.lang.illegalstateexception:stream at org.eclipse.jetty.server.response.getwriter（response）时出错。java:693)在javax.servlet.servletresponsewrapper.getwriter（servletresponsewrapper。java:152)在servlet.servletresponsewrapper.getwriter（servletresponsewrapper。java:152)位于org.springframework.security.web.context.savecontextonupdateorerrorresponsewrapper.getwriter（savecontextonupdateorerrorresponsewrapper。java:125)在org.apache.wicket.protocol.http.servlet.servletwebresponse.write（servletwebresponse。java:109)在org.apache.wicket.protocol.http.headerbufferingwebresponse.write（headerbufferingwebresponse。java:179)在org.apache.wicket.protocol.http.bufferedwebresponse$writecharsequenceaction.invoke（bufferedwebresponse）中。java:171)在org.apache.wicket.protocol.http.bufferedwebresponse.writeto（bufferedwebresponse。java:602)在org.apache.wicket.request.handler.render.webageender.respond（webageender。java:232)在org.apache.wicket.core.request.handler.renderPagerRequestHandler.respond（renderPagerRequestHandler。java:175)在org.apache.wicket.request.cycle.requestcycle$handlerexecutor.respond（requestcycle。java:890)在org.apache.wicket.request.requesthandlerstack.execute（requesthandlerstack。java:64)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（requestcycle。java:310)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（requestcycle。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（请求周期。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（requestcycle。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（requestcycle。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（请求周期。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（requestcycle。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（requestcycle。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（请求周期。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（requestcycle。java:319)在org.apache.wicket.request.cycle.requestcycle.executeexceptionrequesthandler（requestcycle。java:319)在org.apache.wicket.request.cycle.requestcycle.processrequest（请求周期。java:233)在org.apache.wicket.request.cycle.requestcycle.processrequestanddetach（requestcycle。java:289)在org.apache.wicket.protocol.http.wicketfilter.processrequestcycle（wicketfilter。java:259)在org.apache.wicket.protocol.http.wicketfilter.processrequest（wicketfilter。java:201)在org.apache.wicket.protocol.http.wicketfilter.dofilter（wicketfilter。java:282)位于org.eclipse.jetty.servlet.servlethandler$cachedchain.dofilter（servlethandler。java:1484)在org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter（filterchainproxy。java:330)位于org.springframework.security.web.context.securitycontextpersistencefilter.dofilter（securitycontextpersistencefilter）。java:87)在org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter（filterchainproxy。java:342)在org.springframework.security.web.filterchainproxy.dofilternternal（filterchainproxy。java:192)在org.springframework.security.web.filterchainproxy.dofilter（filterchainproxy。java:160)在org.springframework.web.filter.delegatingfilterproxy.invokedelegate（delegatingfilterproxy。java:346)在org.springframework.web.filter.delegatingfilterproxy.dofilter（delegatingfilterproxy。java:262)位于org.eclipse.jetty.servlet.servlethandler$cachedchain.dofilter（servlethandler。java:1484)位于org.springframework.orm.hibernate4.support.opensessioninviewfilter.dofilternternal（opensessioninviewfilter）。java:151)在org.springframework.web.filter.onceperrequestfilter.dofilter（onceperrequestfilter。java:107)位于org.eclipse.jetty.servlet.servlethandler$cachedchain.dofilter（servlethandler。java:1476)位于org.eclipse.jetty.servlet.servlethandler.dohandle（servlethandler。java:501)在org.eclipse.jetty.server.handler.scopedhandler.handle（scopedhandler。java:137)在org.eclipse.jetty.security.securityhandler.handle（securityhandler。java:557)位于org.eclipse.jetty.server.session.sessionhandler.dohandle（sessionhandler。java:231)在org.eclipse.jetty.server.handler.contexthandler.dohandle（contexthandler。java:1086)位于org.eclipse.jetty.servlet.servlethandler.doscope（servlethandler。java:429)在org.eclipse.jetty.server.session.sessionhandler.doscope（sessionhandler。java:193)在org.eclipse.jetty.server.handler.contexthandler.doscope（contexthandler。java:1020)在org.eclipse.jetty.server.handler.scopedhandler.handle（scopedhandler。java:135)在org.eclipse.jetty.server.handler.contexthandlercollection.handle（contexthandlercollection。java:255) 在org.eclipse.jetty.server.handler.handlercollection.handle（handlercollection。java:154)位于org.eclipse.jetty.server.handler.handlerwrapper.handle（handlerwrapper）。java:116)在org.eclipse.jetty.server.server.handle（server。java:370)位于org.eclipse.jetty.server.abstracthttpconnection.handlerequest（abstracthttpconnection）。java:494)在org.eclipse.jetty.server.abstracthttpconnection.content（abstracthttpconnection）。java:982)位于org.eclipse.jetty.server.abstracthttpconnection$requesthandler.content（abstracthttpconnection）。java:1043)在org.eclipse.jetty.http.httpparser.parsenext（httpparser。java:865)在org.eclipse.jetty.http.httpparser.parseavailable（httpparser。java:240)在org.eclipse.jetty.server.asynchttpconnection.handle（asynchttpconnection）。java:82)在org.eclipse.jetty.io.nio.selectchannelendpoint.handle（selectchannelendpoint。java:696)在org.eclipse.jetty.io.nio.selectchannelendpoint$1.run（selectchannelendpoint.org.eclipse.jetty.io.nio.selectchannelendpoint$1.run）。java:53)在org.eclipse.jetty.util.thread.queuedthreadpool.runjob（queuedthreadpool。java:608)在org.eclipse.jetty.util.thread.queuedthreadpool$3.run（queuedthreadpool。java:543)在java.lang.thread.run（线程。java:748)
我错过了什么吗。请帮忙