Error in writing custom action

Question

Hi
I wanted to create a new action, so I read "Writing Custom Actions" section in JHeadstart Developer's Guide.
As mentioned in the Developer's Guide, I chose JhsAction as super class and extended a new class called GenerateChart and overrode validateProperties and execute methods.
I wrote a new method in my action class called getData() to retrieve information from model to use in execute method.
here is its specification :
private void getData (SessionData sessionData, JhsActionMapping mapping)
Then as mentioned in the developer's guide (page 2-38) I got the sesion id and passed it to getHandler method.
     // retrieve Session Id from SessionData
     Object sessionId = sessionData.getSessionId();
     // Get the DataObject handler
     DataObjectHandler handler =
     (DataObjectHandler)getHandler("myClass", sessionId);
Surprisingly, I received following compilation error :
Error(48,26): method getHandler(java.lang.String, java.lang.Object) not found in class com.behincara.controller.struts.action.GenerateChart
I read getDataObject and getDataObjectSet sources and realized that they use getHandler with sessionData instead of sessionId.
Is it a mistake in Developer's Guide?
Then I changed the code to the following
// retrieve Session Id from SessionData
Object sessionId = sessionData.getSessionId();
// Get the DataObject handler
DataObjectHandler handler =
(DataObjectHandler) getHandler("myClass", sessionData);
and I received another error
Error(48,36): unreported exception: java.lang.Exception; must be caught or declared to be thrown
Then I copied these lines to execute method and surprisingly I received no error.
Where is my mistake?
Could anybody help me?

Answer 1

Hi Navid,
You wrote:
I read getDataObject and getDataObjectSet sources and
realized that they use getHandler with sessionData
instead of sessionId.
Is it a mistake in Developer's Guide? You are right, it is a mistake in the Developer's Guide. I have logged a doc bug for it, so we can correct it in a future version.
A more reliable source for this kind of information is the JHeadstart JavaDoc, which you can find at J:\jheadstart\doc\api\index.html (where J: is the JHeadstart home). If you look up JhsAction there, you will find detailed information about the methods you can use in your custom actions.
... I received another error
Error(48,36): unreported exception:
java.lang.Exception; must be caught or declared to be
thrown
Then I copied these lines to execute method and
surprisingly I received no error.
Where is my mistake?Your mistake is that your method getData does not throw an Exception, and the execute method does. If you change the signature of getData to be as follows:
private void getData (SessionData sessionData, JhsActionMapping mapping)
throws Exception
(add the last two words), then you can also put the getHandler lines in getData.
Hope this helps,
Sandra Muller
JHeadstart Team