H5-Class Hierarchies

Question 1

What exception type can you use when a parameter is not in the expected rainge? e.g. string that is null, or empty.

Answer 1

ArgumentOutOfRangeException

Question 2

How do you inherit from a parent class?

Answer 2

public class child : parent{

Question 3

Does a child class inherit the constructor of the parent?

Answer 3

No, so if the parent has a constructor parentconstructer(parameter1, parameter2) then the child could still use new child() as a constructor.

Question 4

How do you call the constructor of the parent?

Answer 4

public Employee(string firstName, string lastName,
string departmentName)
: base(firstName, lastName)
{
do something with departmentName
rest of parameters go to constructor for parent.

Question 5

What get’s executed first? parent or child constructor?

Answer 5

When a constructor uses the base keyword to invoke a base class constructor,
the base class’s constructor executes before the body of the child
class’s constructor executes.

Question 6

What happens when the parent has only 1 constructor with parameters? What does the child have to do?

Answer 6

If both the parent and child class have constructors, the child class’s constructor must invoke
one of the parent class’s constructors

Question 7

what happens if the parent has 1 constructor that has parameters and the child is ChildConstrutor()
{
..
}

Answer 7

.Net will implicitly look for the parent construtor with no parameters. As this is not there an complition error will occure.

Question 8

What will happen when the child class does not have a constructor and the parent only has a construtor with parameters?

Answer 8

It will still work, this is the only situation where the child does not call the base() parent implicenty.

Question 9

How can you call a other constructor in the same class?

Answer 9

MyConstructor(String age, String name) : this (name)
{
store agem name was already processed by the call to this(name)
}

Question 10

When calling a other constructor in the same class? who get’s executed first?

Answer 10

The constructor called with this(…) same as the base(…) call.

Question 11

What is a best practice when you want to use 2 different constructors in the same class?

Answer 11

Put the actual code in methodes and call the methodes not the constructors.

public Customer(string email)
{StoreEmail(email);}

public Customer(Address address){ StoreAddress(address);}

public Customer(string email, Address address)
{ 
StoreEmail(email); 
StoreAddress(address);}

// Store the email address.
private void StoreEmail(string email){ ...}

// Store the postal address.
private void StoreAddress(Address address){ ...}