Mock Question - Bean Standard Action

[Vishnu Prakash]

which of the following useBean actions allow us to locate an existing bean object of MyBean class having the id theBean in the current session without creating a new instance if an existing instance is not available? select one chice.

Options:

1. <jsp:useBean id="theBean" type="MyBean" scope="session" />
2. <jsp:useBean id="theBean" class="MyBean" scope="session" />
3. <jsp:useBean id="theBean" beanName="MyBean" type="MyBean" scope="session" />
4. <jsp:useBean id="theBean" class="MyBean" type="MyBean" scope="session" />

without creating a new instance if an existing instance is not available?

This part of the question is pretty unclear to me. I appreciate if any one can explain it to me.

[Christophe Verré]

Pretty confusing indeed

I think it should have said :
"Which of the following useBean actions allow us to locate an existing bean object of MyBean class having the id theBean in the current session", and stop here.
"without creating a new instance if an existing instance is not available" makes it all confusing. They wanted to insist on the "not create a new one".

[Vishnu Prakash]

They wanted to insist on the "not create a new one".

If thats the case then option 1 is correct.

[P Chittaranjan]

Hi,

Option 1 is correct . Because it will try to find the object "theBean" in session scope. if It will not find the object,it can not create a object.
For creating the a new object we need either the "beanName" or "class" attribute along with the "type" attribute.

What I feel is, scince a type can be an Interface , <jsp:useBean id="theBean" type="MyBean" scope="session" /> This should fail to create a new object , if no object is there with that name.

Thanks
Chittaranjan

[jim bop]

Option one is correct imo. Its my understanding that both type and beanName are required attributes. Correct me if I'm wrong.

[P Chittaranjan]

Hi Jim,

You are right. Option 1 is correct. But "type" will work with the following combination.

1.type
2.type and beanName
3.type and class

So in the following question:

which of the following useBean actions allow us to locate an existing bean object of MyBean class having the id theBean in the current session without creating a new instance if an existing instance is not available? select one chice.

Options:

1. <jsp:useBean id="theBean" type="MyBean" scope="session" />
2. <jsp:useBean id="theBean" class="MyBean" scope="session" />
3. <jsp:useBean id="theBean" beanName="MyBean" type="MyBean" scope="session" />
4. <jsp:useBean id="theBean" class="MyBean" type="MyBean" scope="session" />

Option 1 will look for an existing bean in session scope. If it is there, use it.Otherwise it won't create a new bean object.

Hope, it will help you.

Thanks

[Nicholas Way]

So what does "beanName" do that "class" doesn't?

[P Chittaranjan]

1.beanName attribute can refer to a serialized bean as well as a class. i.e if you have beanName="rancher.ranchedAddress.John" which is representing a serialized bean, the container will load the bean from rancher/rancherAddress/John.ser file. Here .ser is the extention for a serialized file.

Where as class attribute can only refer to the .class file.

2.beanName can accept request-time attribute expression.But class attribute can not.

Thanks
Chittaranjan

[Vishnu Prakash]

Nice explanation Chittaranjan. Thanks.

I wish these notes where present in HFSJ.