public

[Doit]

public class A
{
A()
{
}
}
1.The class A can be referenced outside the package in which it is defined.
2.The class A cannot be instantiated outside the package in which it is defined.
3.The class A cannot be extended outside the package in which it is defined.
were the given answers. Why 2 and 3 are true? Anyidea?
- Thanks

[Mapraputa Is]

Idea: because the constructor is not declared as public, it is declared with default (zero) access modifier = package visibility. But I am not sure, I also would choose only 1 as right answer...

[yanish]

Mapraputa's idea is completely correct. A main point here is that a default constructor has been defined with package accessibility. So, there are no any ways to instantiate the class (or extend the class) outside the package where it is defined.

[Anonymous]

I am not clear !!! Why is (1) wrong? Since the class is public we can a refernce of this class outside. For eg:
package OtherPackage;
public class A
{
A(){}
}
public class B extends A
{
public B(){}
public A returnReference()
{
return new A();
}
}
Now consider this:
package P;
class Test
{
OtherPackage.A a = new B().returnReference();
}
So, out here u are able to reference class A outside the package. So, how can we say that the class A can be referenced outside the package in which it is defined?
Shouldn't (1) be true as well??
Please correct me if I am wrong!!
- sampaths77