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struts - Struts2 list couldn't be resolved

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struts - Struts2 list couldn't be resolved

please help me. I am facing this error for 3 days. I have searched all the examples on the web, but I couldn't figured it out.

These are my files:

struts.xml

...
<action name="menu"  class="com.struts.actions.MenuAction" method="asdf">
<result name="success" type="tiles">struts2tiles.home</result>
</action>
...

menu2.jsp

....
<body>
<s:form action="menu">
    <s:checkboxlist label="What's your favor color" list="colors" name="colors" />

<s:submit value="submit" name="submit" />

</s:form>
</body>

MenuAction

public class MenuAction extends ActionSupport {
    private ArrayList<String> colors;
    private String yourColor;

    public ArrayList<String> getColors() {
        return colors;
    }

    public void setColors(ArrayList<String> colors) {
        this.colors = colors;
    }

    public String getYourColor() {
        return yourColor;
    }

    public void setYourColor(String yourColor) {
        this.yourColor = yourColor;
    }

    public String asdf() {
        colors = new ArrayList<String>();
        colors.add("red");
        colors.add("yellow");
        colors.add("blue");
        colors.add("green");

        return SUCCESS;
    }

    @Override
    public String execute() {
        System.out.println("execute menu action");
        colors = new ArrayList<String>();
        colors.add("red");
        colors.add("yellow");
        colors.add("blue");
        colors.add("green");

        return SUCCESS;
    }

}

Anything I did, still the same error persists:

Dec 22, 2011 10:56:44 PM org.apache.catalina.core.ApplicationDispatcher invoke
SEVERE: Servlet.service() for servlet jsp threw exception
tag 'checkboxlist', field 'list', name 'colors': The requested list key 'colors' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]
    at org.apache.struts2.components.Component.fieldError(Component.java:237)
    at org.apache.struts2.components.Component.findValue(Component.java:358)
    at org.apache.struts2.components.ListUIBean.evaluateExtraParams(ListUIBean.java:80)
    at org.apache.struts2.components.UIBean.evaluateParams(UIBean.java:856)
    at org.apache.struts2.components.UIBean.end(UIBean.java:510)
    at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
    at org.apache.jsp.jsp.common.menu2_jsp._jspx_meth_s_005fcheckboxlist_005f0(menu2_jsp.java:166)
    at org.apache.jsp.jsp.common.menu2_jsp._jspx_meth_s_005fform_005f0(menu2_jsp.java:122)
    at org.apache.jsp.jsp.common.menu2_jsp._jspService(menu2_jsp.java:84)
    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:433)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
    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:80)
    at org.apache.tiles.jsp.context.JspTilesRequestContext.dispatch(JspTilesRequestContext.java:73)
    at org.apache.tiles.context.TilesRequestContextWrapper.dispatch(TilesRequestContextWrapper.java:72)
    at org.apache.struts2.tiles.StrutsTilesRequestContext.dispatch(StrutsTilesRequestContext.java:88)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:283)
    at org.apache.tiles.jsp.taglib.InsertAttributeTag.render(InsertAttributeTag.java:140)
    at org.apache.tiles.jsp.taglib.InsertAttributeTag.render(InsertAttributeTag.java:117)
    at org.apache.tiles.jsp.taglib.RenderTagSupport.execute(RenderTagSupport.java:154)
    at org.apache.tiles.jsp.taglib.RoleSecurityTagSupport.doEndTag(RoleSecurityTagSupport.java:75)
    at org.apache.tiles.jsp.taglib.ContainerTagSupport.doEndTag(ContainerTagSupport.java:80)
    at org.apache.jsp.jsp.common.mainLayout_jsp._jspx_meth_tiles_005finsertAttribute_005f2(mainLayout_jsp.java:181)
    at org.apache.jsp.jsp.common.mainLayout_jsp._jspService(mainLayout_jsp.java:94)
    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:433)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
    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.tiles.servlet.context.ServletTilesRequestContext.include(ServletTilesRequestContext.java:217)
    at org.apache.tiles.servlet.context.ServletTilesRequestContext.dispatch(ServletTilesRequestContext.java:177)
    at org.apache.tiles.context.TilesRequestContextWrapper.dispatch(TilesRequestContextWrapper.java:72)
    at org.apache.struts2.tiles.StrutsTilesRequestContext.dispatch(StrutsTilesRequestContext.java:88)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:606)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:246)
    at org.apache.struts2.views.tiles.TilesResult.doExecute(TilesResult.java:105)
    at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186)
    at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:373)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:277)
    at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:263)
    at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:270)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
    at org.apache.struts2.components.ActionComponent.executeAction(ActionComponent.java:291)
    at org.apache.struts2.components.ActionComponent.end(ActionComponent.java:173)
    at org.apach

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1 Answer

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by (71.8m points)

The requested list key 'colors' could not be resolved as a collection/array/map/enumeration/iterator type

This error occurs when you try to access a list/collection which haven't been created.

May be you are calling action directly i.e. loacalhost:8080/youraction.action.

Please ensure that you access list after the action class is instantiated i.e. corresponding action is called.

If you want to directly access it before calling action make it static and access it inside jsp.


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