Auto-instantiate session-scoped bean from view-scoped bean - jsf-2

Question

Every time I try to inject a session-scoped bean into my view-scoped beans, I get a NullPointerException when calling said bean. This problem is directly related to auto -instantiate a session bean?
Here is what I tried so far:
faces-config.xml
<managed-bean>
<managed-bean-name>sessionBean</managed-bean-name>
<managed-bean-class>com.example.SessionBean</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
<managed-bean>
<managed-bean-name>viewBean</managed-bean-name>
<managed-bean-class>com.example.ViewBean</managed-bean-class>
<managed-bean-scope>view</managed-bean-scope>
<managed-property>
<property-name>sessionBean</property-name>
<property-class>com.example.SessionBean</property-class>
<value>#{sessionMBean}</value>
</managed-property>
</managed-bean>
SessionBean.java:
package com.example;
public class SessionBean {
public SessionBean() {
System.out.println("Session is instantiated.");
}
public void sayHello() {
System.out.println("Hello from session");
}
}
ViewBean.java:
package com.example;
public class ViewBean {
private SessionBean sessionBean;
private String text = "Look at me!";
public ViewBean() {
System.out.println("View bean is instantiated.");
sessionBean.sayHello();
}
public SessionBean getSessionBean() {
return sessionBean;
}
public void setSessionBean(SessionBean sessionBean) {
this.sessionBean = sessionBean;
}
public String getText() {
return text;
}
}
and the relevant content of index.xhtml:
<f:view>
<h:outputText value="#{viewBean.text}"/>
</f:view>
And this is what I get:
com.sun.faces.mgbean.ManagedBeanCreationException: Cant instantiate class: com.example.ViewBean.
...
Caused by: java.lang.NullPointerException
at com.example.ViewBean.(ViewBean.java:12)
This runs (or rather doesn't run) on weblogic-10.3.6 with the shipped jsf-2-0.war deployed as a library.
What am I doing wrong here? I'm hoping this is not a container bug...

Answer 1

You cannot access the #SessionScoped bean in the #ViewScoped constructor. The #SessionScoped bean will be set AFTER the constructor of the #ViewScoped bean has been called.
Use the #PostConstruct annotation in some kind of init method to access the #SessionScoped bean.
public ViewBean() {
System.out.println("Constructor viewbean");
}
#PostConstruct
public void init() {
sessionBean.sayHello();
}
Further Links:
Why use #PostConstruct?
Spring Injection - access to the injected object within a constructor