MCTS 70-536 Question Bank

QUESTION 3
You work as an application developer at megaposts.net . You are creating a custom
exception class named ProductDoesNotExistException so that custom exception
messages are displayed in a new application when the product specified by users is
unavailable.
This custom exception class will take the ProductID as an argument to its
constructor and expose this value through the ProductID. You are now in the
process of creating a method named UpdateProduct. This method will be used to
generate and manage the ProductDoesNotExistException exception if the
ProductID variable contains the value 0.
You need to ensure that use the appropriate code for the UpdateProduct method.
What should you do?
A. Make use of the following code:
public void UpdateProduct ()
{
try
{
if (ProductID == 0)
throw new ProductDoesNotExistException (ProductID);
}
catch (ProductDoesNotExistException ex)
{
MessageBox.Show (”There is no Product” + ex. ProductID);
}
}
B. Make use of the following code:
public void UpdateProduct ()
{
try
{
if (ProductID = = 0)
throw new Exception (”Invalid ProductID”);
}
catch (ProductDoesNotExistException ex)
{
MessageBox.Show (ex.Message);
}
}
C. Make use of the following code:
public void UpdateProduct ()
{
if (ProductID = = 0)
throw new ProductDoesNotExistException (ProductID);
}
D. Make use of the following code:
public void UpdateProduct ()
{
if (ProductID = = 0)
throw new Exception (”Invalid ProductID”);
}
…
…
…
Answer: A
Explanation: This code verifies the value of the ProductID variable by using the if
statement. If the ProductID variable contains a value of 0, this code generates an
exception of type ProductDoesNotExistException. To explicitly generate an
exception, you are required to use the throw statement. The exception generated by
using the throw statement can be handled by the try…catch block. This code
generates the custom exception by calling the constructor of the custom exception
class named ProductDoesNotExistException. The constructor argument is the
ProductID attached to the ProductDoesNotExistException object. This code then
handles the custom exception named ProductDoesNotExistException by using a
catch block, which handles exceptions by using a variable named ex of the type
ProductDoesNotExistException. This code displays the “There is no Product” error
message by using the MessageBox.Show method and concatenating the
ex.ProductID to it.
Incorrect Answers:
B: You should not use the code that generates an exception of the type Exception
and handles the exception of the type ProductDoesNotExistException in the
catch block. This code is incorrect because you are required to generate a custom
exception named ProductDoesNotExistException.
C, D: You should not use the codes that do not use a try…catch block because the
application an unhandled exception.

Refrence : MCTS 70-536 Question Bank