dev@javaserverfaces.java.net

Re: Is JSF incompatible with generics?

From: Ilya Shaikovsky <ishaikovsky_at_exadel.com>
Date: Tue, 09 Jun 2009 17:02:50 +0300

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Regards!

Freire, Jose Luis (PT - Lisbon) пишет:
>
> Using JSF 1.2.12, Facelets 1.1.14, Tomcat 6.0.18.
>
>
>
> I’m not sure where to open this bug, since I’m not sure if it’s JSF,
> Facelets, or EL related.
>
>
>
> If we have this simple class:
>
> *public* *class* GenericsTestController<E *extends* Object> {
>
>
>
> *private* E value;
>
>
>
> *public* E getValue() {
>
> *return* value;
>
> }
>
>
>
> *public* *void* setValue(E value) {
>
> *this*.value = value;
>
> }
>
> }
>
>
>
> And we have this class to use as a managed bean (integerTest):
>
> *public* *class* IntegerTestController *extends*
> GenericsTestController<Integer> {
>
>
>
> *public* String add() {
>
> setValue(getValue()+1);
>
> *return* *null*;
>
> }
>
> *public* String subtract() {
>
> setValue(getValue()-1);
>
> *return* *null*;
>
> }
>
> }
>
>
>
> This JSF code will not work:
>
> <h:form>
>
> Value:
>
> <h:inputText value="#{integerTest.value}" />
>
> <h:commandButton action="#{integerTest.add}" value="+" />
>
> <h:commandButton action="#{integerTest.subtract}" value="-" />
>
> </h:form>
>
>
>
> With this error:
>
> _java.lang.ClassCastException_: java.lang.String cannot be cast to
> java.lang.Integer
>
> at
> genericstest.IntegerTestController.add(_IntegerTestController.java:18_)
>
> at sun.reflect.NativeMethodAccessorImpl.invoke0(_Native Method_)
>
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(_NativeMethodAccessorImpl.java:39_)
>
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(_DelegatingMethodAccessorImpl.java:25_)
>
> at java.lang.reflect.Method.invoke(_Method.java:597_)
>
> at org.apache.el.parser.AstValue.invoke(_AstValue.java:172_)
>
> at
> org.apache.el.MethodExpressionImpl.invoke(_MethodExpressionImpl.java:276_)
>
> at
> com.sun.facelets.el.TagMethodExpression.invoke(_TagMethodExpression.java:68_)
>
> at
> javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(_MethodBindingMethodExpressionAdapter.java:88_)
>
> at
> com.sun.faces.application.ActionListenerImpl.processAction(_ActionListenerImpl.java:102_)
>
> at javax.faces.component.UICommand.broadcast(_UICommand.java:387_)
>
> at
> javax.faces.component.UIViewRoot.broadcastEvents(_UIViewRoot.java:475_)
>
> at
> javax.faces.component.UIViewRoot.processApplication(_UIViewRoot.java:756_)
>
> at
> com.sun.faces.lifecycle.InvokeApplicationPhase.execute(_InvokeApplicationPhase.java:82_)
>
> at com.sun.faces.lifecycle.Phase.doPhase(_Phase.java:100_)
>
> at
> com.sun.faces.lifecycle.LifecycleImpl.execute(_LifecycleImpl.java:118_)
>
> at javax.faces.webapp.FacesServlet.service(_FacesServlet.java:265_)
>
> 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:128_)
>
> 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:286_)
>
> at
> org.apache.coyote.http11.Http11Processor.process(_Http11Processor.java:845_)
>
> at
> org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(_Http11Protocol.java:583_)
>
> at
> org.apache.tomcat.util.net.JIoEndpoint$Worker.run(_JIoEndpoint.java:447_)
>
> at java.lang.Thread.run(_Thread.java:619_)
>
>
>
> In fact, it fails with the same error even if we override getValue and
> setValue on IntegerTestController.
>
>
>
> The only workaround is not to extend from GenericsTestController and
> implement the “value” property as Integer in the IntegerTestController.
>
>
>
> Help anyone?**
>
> * *
>
> *José Freire
> *Consulting - Financial Services Industry
> Deloitte Consultores, S.A.
> Deloitte | Edifício Atrium Saldanha, Praça Duque de Saldanha, 1 - 7º,
> 1050-094 Lisboa, Portugal
> Tel/Direct: +(351) 210 422 500 | Fax: +(351) 210 422 950
> jfreire_at_deloitte.pt | www.deloitte.pt
>
> Please consider the environment before printing.
>
>
>
>
>
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