[Java Programmer Certification Mock Exam (Dan Chisholm) wrong solution..

[avi sinha]

   Question 7
interface I1 {}  interface I2 {}
class Base implements I1 {}
class Sub extends Base implements I2 {}
class Orange {
  public static void main(String args[]) {
    Base base = new Base();
    I1 i1 = base;           // 1
    Sub sub = (Sub)base;    // 2
}}

What is the result of attempting to compile and run the program? 
a. 	Compile-time error at line 1
b. 	Run-time error at line 1
c. 	Compile-time error at line 2
d. 	Run-time error at line 2
e. 	None of the above 

i think the answer should be e . line no 2 marked in the question will never throw exception because we are not trying to use the reference variable "sub". but the answer given in the book is "d".[Java Programmer Certification Mock Exam
(Dan Chisholm)]
is it correct sir??

[Marcus Green]

What happened when you compiled and ran the code?

[sudipto shekhar]

Exception in thread "main" java.lang.ClassCastException: Base cannot be cast to Sub
at Orange.main(Orange.java:10)

It is a compile time error as the object of the super type cannot to cast to its subtype. Yes you are correct as far as I think.

[Ulf Dittmer]

sudipto shekhar wrote:

Exception in thread "main" java.lang.ClassCastException: Base cannot be cast to Sub

It is a compile time error as the object of the super type cannot to cast to its subtype. Yes you are correct as far as I think.

What you posted is a runtime error, not a compile time error. But either way, "e" -which the first post suggested- is not correct.

[Chaitanya Jadhav]

NOT wrong solution.

the option d is right.(RuntimeException at line number 2)

[avi sinha]

thanks alot everyone..i got the point..i was a bit wrong.

[sudipto shekhar]

Sorry