About Question enthuware.oce-jpad.v6.2.546 :

[sacintha]

How can an abstract class have a No-arg constructor

[admin]

An abstract class can certainly have a no-args constructor.
-Paul.

[unknownartist]

"Identify the correct statements about following code"

Answer is "It must have no-args constructor."

But I think answer must be "It is a valid @Entity class."

Because no-args constructor will be created by compiler.

[admin]

"Identify the correct statements about following code"

Answer is "It must have no-args constructor."

But I think answer must be "It is a valid @Entity class."

Because no-args constructor will be created by compiler.

In the given class code, an explicit constructor is already present:

Code: Select all

public Vehicle(String code){ mfgCode = code; }

So the compiler will not create the no-args constructor. That is why it is not a valid Entity class.

HTH,
Paul.

[ikotev]

By the way entity has public field:

public String mfgCode;

and as per section "2.2 Persistent Fields and Properties" of the specification:

The instance variables of a class must be private, protected, or package visibility independent of whether field access or property access is used.

does anyone know why RI EclipseLink accepts public fields in entities and doesn't throw exceptions ?

[admin]

Yes, this is another reason why the entity is invalid.
Regarding why EclipseLink accepts public fields, I think that is just an oversight. There are several instances where RI or other persistence providers does not follow the specification to the dot. I think we have noted such cases in some of our questions as well.

HTH,
Paul.