목록이있는 JSP의 NumberFormatException

Question

이 질문은 here으로 설명한 내 응용 프로그램과 관련된 다른 문제입니다. 내 모델 (레벨)에는 ID와 이름의 두 문자열이 포함 된 요구 사항 목록이 있습니다.

public class Level { 
private String name; 
private int id; 
private int points 
private List<Requirement> requirements; 
    .... 
} 

public class Requirement{ 
    private String name; 
    private String id; 
    .... 
} 

및 JSP는 다음과 같습니다 :이 모델은 다음과 같습니다 JSP 페이지가 잘 렌더링하고 나는 사이트가 java.lang.NumberFormatException: For input string: "id"을 발생하는 requiredRequirements 루프를 추가 할 때까지 마법처럼 작동

<div id="allRequirements"> 
    <c:forEach var="requirement" items="${RequirementList}"> 
     <div class="requirements"> 
      <input type="hidden" value="${requirement.id}" name="id"/> 
      <h2><c:out value="${requirement.name}"/></h2> 
     </div> 
    </c:foreach> 
</div> 

<div id="requiredRequirements"> 
    <c:forEach var="requiredRequirement" items="${level.requirements}"> 
     <div class="requirements"> 
      <input type="hidden" value="${requiredRequirement.id}" name="id"/> 
      <h2><c:out value="${requiredRequirement.name}"/></h2> 
     </div> 
    </c:foreach> 
</div> 

문자열을 int로 구문 분석하려고하기 때문입니다.

첫 번째 루프가 작동하고 두 번째 루프가 작동하지 않는 이유는 누구나 알 수 있습니까?

편집 : 스택 추적

java.lang.NumberFormatException: For input string: "id" 
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48) 
at java.lang.Integer.parseInt(Integer.java:447) 
at java.lang.Integer.parseInt(Integer.java:497) 
at javax.el.ListELResolver.coerce(ListELResolver.java:174) 
at javax.el.ListELResolver.getValue(ListELResolver.java:52) 
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67) 
at org.apache.el.parser.AstValue.getValue(AstValue.java:169) 
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189) 
at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:985) 
at org.apache.jsp.WEB_002dINF.jsp.createOrEdit_005fLevelBody_jsp._jspx_meth_c_005fout_005f0(createOrEdit_005fLevelBody_jsp.java:648) 
at org.apache.jsp.WEB_002dINF.jsp.createOrEdit_005fLevelBody_jsp._jspx_meth_c_005fforEach_005f1(createOrEdit_005fLevelBody_jsp.java:611) 
at org.apache.jsp.WEB_002dINF.jsp.createOrEdit_005fLevelBody_jsp._jspService(createOrEdit_005fLevelBody_jsp.java:207) 
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419) 
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391) 
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684) 
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:593) 
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:530) 
at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:927) 
at org.apache.jasper.runtime.PageContextImpl.doInclude(PageContextImpl.java:684) 
at org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:678) 
at org.apache.tiles.jsp.context.JspTilesRequestContext.include(JspTilesRequestContext.java:103) 
at org.apache.tiles.jsp.context.JspTilesRequestContext.dispatch(JspTilesRequestContext.java:96) 
at org.apache.tiles.renderer.impl.UntypedAttributeRenderer.write(UntypedAttributeRenderer.java:61) 
at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:103) 
at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:659) 
at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:337) 
at org.apache.tiles.jsp.taglib.InsertAttributeTag.render(InsertAttributeTag.java:234) 
at org.apache.tiles.jsp.taglib.InsertAttributeTag.render(InsertAttributeTag.java:211) 
at org.apache.tiles.jsp.taglib.RenderTag.doEndTag(RenderTag.java:220) 
at org.apache.jsp.WEB_002dINF.jsp.layout_jsp._jspx_meth_tiles_005finsertAttribute_005f3(layout_jsp.java:411) 
at org.apache.jsp.WEB_002dINF.jsp.layout_jsp._jspService(layout_jsp.java:196) 
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419) 
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391) 
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684) 
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:593) 
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:530) 
at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:927) 
at org.apache.jasper.runtime.PageContextImpl.doInclude(PageContextImpl.java:684) 
at org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:678) 
at org.apache.tiles.jsp.context.JspTilesRequestContext.include(JspTilesRequestContext.java:103) 
at org.apache.tiles.jsp.context.JspTilesRequestContext.dispatch(JspTilesRequestContext.java:96) 
at org.apache.tiles.renderer.impl.TemplateAttributeRenderer.write(TemplateAttributeRenderer.java:44) 
at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:103) 
at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:659) 
at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:678) 
at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:633) 
at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:322) 
at org.apache.tiles.jsp.taglib.InsertDefinitionTag.renderContext(InsertDefinitionTag.java:66) 
at org.apache.tiles.jsp.taglib.InsertTemplateTag.render(InsertTemplateTag.java:81) 
at org.apache.tiles.jsp.taglib.RenderTag.doEndTag(RenderTag.java:220) 
at org.apache.jsp.WEB_002dINF.jsp.createOrEdit_005fLevel_jsp._jspx_meth_tiles_005finsertDefinition_005f0(createOrEdit_005fLevel_jsp.java:87) 
at org.apache.jsp.WEB_002dINF.jsp.createOrEdit_005fLevel_jsp._jspService(createOrEdit_005fLevel_jsp.java:60) 
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419) 
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391) 
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684) 
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:471) 
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:402) 
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329) 
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238) 
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250) 
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047) 
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817) 
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719) 
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669) 
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:574) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) 
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) 
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) 
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) 
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:395) 
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:306) 
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:323) 
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1719) 
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) 
at java.lang.Thread.run(Thread.java:619) 

감사

Answer 1

이 ${requiredRequirement}가 실제로List의 인스턴스 인 것을 의미한다. EL에서 List은 정수 인덱스로만 액세스 할 수 있습니다. 이 2 가지 원인이있을 수 있습니다

는

1. 귀하의 Requirement 클래스는 실제로 List를 구현 또는 그 서브 클래스 중 하나를 확장합니다.
2. ${level} 또는 ${level.requirements}은 실제로 생각하는 코드를 참조하지 않습니다. 자신의 toString() 방법은 당신이 무엇을 기대 반환하는 경우

으로 신속하게 디버그는 확인하기가 일반 인쇄 해보십시오 :

<p>Level: ${level}</p> 
<p>Level requirements: ${level.requirements}</p> 

를 루프

<p>Required requirement: ${requiredRequirement}</p>