seam newbie| trivial example | NullPointerException
I am attempting to create (what should be) a trivial Seam app, following/using some of the code from the hotel booking app, and I am consistently getting a NullPointerException for the first page it should display.
my app has three classes (Calculator.java, Calculate.java and CalculateAction.java) as follows:
Calculator.java:
// Calculator.java
package lab.seam.calc;
import static org.jboss.seam.ScopeType.SESSION;
import org.jboss.seam.annotations.In;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Out;
import org.jboss.seam.annotations.Scope;
@Scope(SESSION)
@Name("calc")
public class Calculator {
public Calculator() {
}
public void multiply() {
result = firstNumber * secondNumber;
}
public void add() {
result = firstNumber + secondNumber;
}
public void setFirstNumber(int n) {
this.firstNumber = n;
}
public void setSecondNumber(int n) {
this.secondNumber = n;
}
public int getFirstNumber() {
return firstNumber;
}
public int getSecondNumber() {
return secondNumber;
}
public int getResult() {
return result;
}
@In
@Out
private int firstNumber;
@In
@Out
private int secondNumber;
@Out
private int result;
}
Calculate.java:
// Calculate.java
package lab.seam.calc;
import javax.ejb.Local;
@Local
public interface Calculate {
public String add();
public String multiply();
}
CalculateAction.java:
//CalculateAction.java
package lab.seam.calc;
import static org.jboss.seam.ScopeType.EVENT;
import javax.ejb.Interceptor;
import javax.ejb.Stateless;
import org.jboss.seam.annotations.In;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Scope;
import org.jboss.seam.ejb.SeamInterceptor;
@Stateless
@Scope(EVENT)
@Name("calculate")
@Interceptor(SeamInterceptor.class)
public class CalculateAction implements Calculate {
public void setCalculator(Calculator c) {
calc = c;
}
public String add() {
calc.add();
return SUCCESS;
}
public String multiply() {
calc.multiply();
return SUCCESS;
}
private static final String SUCCESS = "success";
@In
private Calculator calc;
}
I have three xhtml files: index.xhtml, calculator.xhtml, and results.xhtml
calculator.xhtml looks like (as you can see, not much difference from the hotel app) :
<!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
template="template.xhtml">
<!-- content -->
<ui:define name="content">
<div class="section">
<h1>Calculator</h1>
</div>
<div class="section">
<h:form>
<fieldset>
<div class="entry">
<div class="label"><h:outputLabel for="firstNumber">1st Number:</h:outputLabel></div>
<div class="input"><h:inputText id="firstNumber" value="#{calc.firstNumber}" /><br/>
<span class="errors"><h:message for="firstNumber" /></span></div>
</div>
<div class="entry">
<div class="label"><h:outputLabel for="secondNumber">2nd Number:</h:outputLabel></div>
<div class="input"><h:inputText id="secondNumber" value="#{calc.secondNumber}" /><br/>
<span class="errors"><h:message for="secondNumber" /></span></div>
</div>
<div class="entry errors"><h:messages globalOnly="true"/></div>
<div class="entry">
<div class="label"> </div>
<div class="input">
<h:commandButton value="Add" action="#{calculate.add}" class="button"/>
<h:commandButton value="Multiply" action="#{calculate.multiply}" class="button"/>
</div>
</div>
</fieldset>
</h:form>
</div>
</ui:define>
<!-- sidebar -->
<ui:define name="sidebar">
<h1>Info</h1>
<p>
info info info
</p>
</ui:define>
</ui:composition>
Now the problem:
I can't seem to get calculator.jsf to display. I get a NullPointerException with the following stack trace
java.lang.NullPointerException at org.apache.myfaces.application.jsp.JspStateManagerImpl.restoreTreeStructure(JspStateManagerImpl.java:141) at org.apache.myfaces.application.jsp.JspStateManagerImpl.restoreView(JspStateManagerImpl.java:181) at org.apache.myfaces.application.jsp.JspViewHandlerImpl.restoreView(JspViewHandlerImpl.java:246) at org.apache.myfaces.lifecycle.LifecycleImpl.restoreView(LifecycleImpl.java:113) at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:66) at javax.faces.webapp.FacesServlet.service(FacesServlet.java:94) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:81) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) at org.jboss.web.tomcat.security.CustomPrincipalValve.invoke(CustomPrincipalValve.java:39) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:157) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:59) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527) at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112) at java.lang.Thread.run(Thread.java:595)
I will really appreciate any pointers.
Thanks,
Emmanuel
