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Binding and attr listener - app won't start  RSS feed

 
Greenhorn
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I understand the difference between HttpSessionBindingListener and HttpSessionAttributeListener. But I tried to implement them both in an attribute class, added listener to DD and.... application didn't start at all! I know that it was wrong, but could you tell me why exactly app didn't start?
 
Sheriff
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but could you tell me why exactly app didn't start?


Please post your container's log.
 
Daniel Stankiewicz
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Originally posted by Christophe Verre:

Please post your container's log.



Here you are:

2007-10-04 09:16:11 org.apache.catalina.core.StandardContext listenerStart
SEVERE: Error configuring application listener of class com.example.web.Dog
java.lang.InstantiationException: com.example.web.Dog
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3713)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4216)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:760)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:740)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:544)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:920)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:883)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:492)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1138)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:120)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1022)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:736)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1014)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:448)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:700)
at org.apache.catalina.startup.Catalina.start(Catalina.java:552)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:295)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:433)
2007-10-04 09:16:11 org.apache.catalina.core.StandardContext listenerStart
SEVERE: Skipped installing application listeners due to previous error(s)
 
Ranch Hand
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hi,

what's in the constructor of com.example.web.Dog?

Herman
 
Sheriff
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java.lang.InstantiationException: com.example.web.Dog



Can you post the code to your com.example.web.Dog class?
Be sure to use UBB Code tags when you do.
 
Christophe Verré
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Also make sure there's a public default constructor. But as others said, please post your Dog class as well.
 
Ranch Hand
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What could also be wrong is
Dog is a HttpSessionBindingListener and BindingListeners need not be registered in the web.xml.
The container will automatically figure out that it has to send BindingEvents to objects of this class when they are bound or unbound to the session object.
but this should not necessarily cause an instantiation exception.
so you probably don;t have a no argument public ctor.
regards,
Akshay
[ October 06, 2007: Message edited by: Akshay Kiran ]
 
Daniel Stankiewicz
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The problem was that Dog class didn't have a default public constructor, but just a parametrized constructor. So the container couldn't instantiate this class as a HttpSessionAttributeListener. Thank you all for helping
 
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