Using Bean (View Scope) in JSF to show data

I'm creating an web application, using JSF (2.0). It has "ViewProducts.xhtml" to view Product with page. Each time this page loaded, if parameter has some thing (Eg: page=1 (ViewProduct.xhtml?page=1)), it's will automatically set the id to setPage property in that Bean. But, i'm keeping getting this error:

Unable to create managed bean categories. The following problems were found: - Bean or property class bean.Categories for managed bean categories cannot be found.

Here is my code (Categories act like a product container):

faces-config.xml:

<faces-config version="2.0"
xmlns="http://java.sun.com/xml/ns/javaee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd">
<navigation-rule>
    <from-view-id>/template/header.xhtml</from-view-id>
    <navigation-case>
        <from-outcome>ViewCategories</from-outcome>
        <to-view-id>/ViewCategories.xhtml</to-view-id>
    </navigation-case>
</navigation-rule>

<managed-bean>
    <managed-bean-name>categories</managed-bean-name>
    <managed-bean-class>bean.Categories</managed-bean-class>
    <managed-bean-scope>view</managed-bean-scope>
</managed-bean>

ViewProducts.xhtml

xmlns:c="http://java.sun.com/jsp/jstl/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"



<f:metadata>
    <f:viewParam name="page" value="#{categories.page}"/>
</f:metadata>

<h:dataTable value="#{categories.listProduct}" var="cus">
    <h:column>
        <f:facet name="header">Name</f:facet>
        <h:outputText value ="#{cus.name}"></h:outputText>
    </h:column>
    <h:column>
        <f:facet name="header">Price</f:facet>
        <h:outputText value ="#{cus.price}"></h:outputText>
    </h:column>
</h:dataTable>

Categories.java (ManagedBean)

public class Categories implements Serializable {    
    /** Creates a new instance of categories */
    public Categories() {
    }
    private int page = 0;

    public int getPage() {
        return page;
    }

    public void setPage(int page) {
        this.page = page;
    }
    public List<Product> listProduct = null;

    public List<Product> getListProduct() {
        if (listProduct != null) {
            return listProduct;
        } else {
            listProduct = dataAccess.DataAccess.getCategories(this.page);
            return listProduct;
        }
    }

    public void setListProduct(List<Product> listProduct) {
        this.listProduct = listProduct;
    }开发者_JAVA百科
}

Stack trace:

com.sun.faces.mgbean.ManagedBeanCreationException: Unable to create managed bean categories.  The following problems were found:
     - Bean or property class bean.Categories for managed bean categories cannot be found.
     - Bean or property class bean.Categories for managed bean categories cannot be found.
     - Bean or property class bean.Categories for managed bean categories cannot be found.
     - Bean or property class bean.Categories for managed bean categories cannot be found.
    at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:263)
    at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:86)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:54)
    at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
    at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:69)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:112)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:102)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:178)
    at javax.faces.component.UIData.getValue(UIData.java:554)
    at javax.faces.component.UIData.getDataModel(UIData.java:1248)
    at javax.faces.component.UIData.setRowIndex(UIData.java:447)
    at com.sun.faces.renderkit.html_basic.TableRenderer.encodeBegin(TableRenderer.java:81)
    at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:823)
    at javax.faces.component.UIData.encodeBegin(UIData.java:937)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1611)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:380)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:662)

---

There are at least 3 problems:

1. The bean class bean.Categories is not in the classpath.

2. You cannot have a managed property which is of a narrower scope than the managed bean.

3. You're duplicating the managed property with <f:viewParam>.

Ensure that the bean class is in the classpath and that you didn't typo'ed the managed bean class. You also need to get rid of the <managed-property>, you don't need it if you're already using <f:viewParam>.

Not related to the problem, but as you're already on JSF2, I'd also suggest to use annotations instead of the faces-config.xml.