Simple question about JavaBeans

[Jessid Leon Velez Gutierrez]

Hello. I am studying for SCWCD exam and in one of the questions I found, said that a JavaBean will generate a compile time error just because it does not have non-arg constructor. Explicitly the author of the exam says:

"Since MyBean does not have a no-arg constructor, the container cannot instantiate it and hence a Compilation error
would occur."

MyBean is the class with a no arg-constructor. I think this is wrong, because it would generate a run-time error, when the container tries to instantiate the bean. Am I wrong?

thank you!

The exam i am talking about is Practice Test I, question number 19 from whizlabs.

[Ulf Dittmer]

The problem would be detected at runtime of the web app, but at compile time of the JSP (since that's where the code containing the no-arg constructor is used).

[Jessid Leon Velez Gutierrez]

Ulf Dittmer wrote:The problem would be detected at runtime of the web app, but at compile time of the JSP (since that's where the code containing the no-arg constructor is used).

mmm.... all right Ulf. I think I get it now. Thanks a lot!

[Marcos Vidolin]

Yeap
I think you are rigth.
the compile tries to find out the non-arg constructor because it is in the specification.
How would you do to instantiate the Bean using <jsp:useBean> tag for example, without non-arg constructor?

[wei liu]

isn't the Java class will have a default no-args constructors? so do you need to explicitly define this no-arg constructor？

[Sean Clark]

wei liu wrote:isn't the Java class will have a default no-args constructors? so do you need to explicitly define this no-arg constructor？

Only if you haven't defined any other constructors, if you have then you will need to explicitly create a no-arg construcor as well.

Sean