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Understand high-level programming concepts (such as inheritance, encapsulation, data abstraction, and polymorphism) and how they are implemented. 

Level 2 Programming theory

Joy Horvath

Instructional Designer

Use best practices and Unity's Profiler window to improve performance in code.

Level 1 Code optimization

This quiz will assess your understanding of the concepts covered in the  Junior Programmer: Apply object-oriented principles mission.

Explain how abstraction is used to expose only necessary script components

Explain how inheritance is used to share functionality between a parent and child class

Define the relationship between a parent and child class, including what a child class can and cannot do with respect to its parent class

Recognize opportunities where inheritance could be used to simplify code

Describe how polymorphism can be applied at compile time (method overloads) and run time (method overrides)

Explain how polymorphism is used to modify parent class functionality in a child class

Explain how encapsulation is used to write code that can only be used as intended by the programmer

Recommend a high-level system architecture for a given project 

Simplify code and make it reusable by correctly implementing the principles of inheritance and polymorphism

Expose only the important details of an object by correctly recognizing opportunities to implement abstraction

Control access to data within a class by applying encapsulation with getters and setters

Explain the purpose of interfaces, including their functional usability advantages over standard classes  

Make code more secure and usable by correctly implementing the principles of abstraction and encapsulation, including the use of interfaces

Identify potential simplification opportunities in code, such as splitting methods and reusing variables

Identify unnecessary nested if statements

Differentiate between public variables (properties), private variables (fields), and local variables

Store and organize data by applying data structures such as lists and dictionaries

Maximize code efficiency by correctly executing coding best practices

Enable easier readability and debugging by correctly organizing classes to include only singular purpose code

Add new functionality to non-editable classes by applying extension methods

Organize and prevent conflicts between scripts by using namespaces

Manage the communication of a GameObject’s status changes to other objects in the application by using Events 

Write efficient, organized, and comprehensible code by correctly implementing the principles of object-oriented programming

Deduce the script method that uses the most CPU time (vs. a script method that does not) by using the CPU profiler in the Profiler window 

Differentiate a loop that efficiently goes through a collection once in an Update() call from many loops that go through the same collection in an Update() call 

Recognize possible issues that might cause performance problems (e.g., too many RigidBody components, too many Colliders, too many shadows, etc.), given a scenario 

Investigate performance issues caused by poly count, texture sizes, or too many objects on the screen by using Unity's Stats window 

Deduce the script method that uses the most CPU time (vs. a script method that does not) by using the CPU profiler in the Profiler window

Differentiate a loop that efficiently goes through a collection once in an Update() call from many loops that go through the same collection in an Update() call

Recognize possible issues that might cause performance problems (e.g., too many RigidBody components, too many Colliders, too many shadows, etc.), given a scenario

Investigate performance issues caused by poly count, texture sizes, or too many objects on the screen by using Unity's Stats window

Debug performance issues

Analyze the principal pillars of object-oriented programming

In general, classes should be organized and written such that each class has a singular purpose.

True or False: In general, classes should be organized and written such that each class has a singular purpose.  

Organizing your classes to ensure they are written to include only singular purpose code makes for easier readability and debugging.

Why might you want to use an extension method in C#?

In order to add functionality to an existing type without creating a new derived type. 

In order to extend the access of an existing method so it can be accessed from other classes.

In order to extend the functionality of an existing method using the same method name.

In order to add more parameters to an existing method.

Extension methods effectively allow you to add methods to existing classes that could otherwise not be edited directly. This means that those classes do not need to be recompiled either.

 Which of the following statements are true about parent (base) and child (derived) classes?

A class can only inherit from a single class. 

Protected variables and methods can be accessed from the child class, even if they are separate scripts. 

Private variables and methods can be accessed from the child class, even if they are separate scripts. 

If Class C derives from Class B, which derives from Class A, Class C only inherits behaviors from Class B. 

 Which of the following statements are true about parent (base) and child (derived) classes? A class can only inherit from a single class.  Protected variables and methods can be accessed from the child class, even if they are separate scripts.  Private variables and methods can be accessed from the child class, even if they are separate scripts.  If Class C derives from Class B, which derives from Class A, Class C only inherits behaviors from Class B.   

For number 3, private variables and methods can only be accessed by derived classes if those classes are nested in their base class. For number 4, Class C would actually inherit from all base classes, which would include Class B and Class A.

If you were programming an application that allowed users to configure their own vehicles, how would you use the concept of inheritance to structure the code in a way that minimized redundancies?

Create a method called “InheritCarBehavior”, which pulls in the functionality for a car.

Create a “Car” event, and have all vehicle types inherit from that event.

Create a namespace called “Cars” and put all vehicle types in that namespace.

Create a base “Car” class, then create derived classes for different types of cars. 

Inheritance allows you to create child (derived) classes that inherit all behaviors from their parent (base) classes.

A base class (Class A) includes the following code:

public virtual void Greet () 
{
   Debug.Log("Hello");
}

A derived class (Class B) that derives from Class A includes the following code:

public override void Greet ()
{
   Debug.Log("How are you?");
}

If only Class B is instantiated and the Greet() method is called, what will appear in the console? 

A base class (Class A) includes the following code: public virtual void Greet () 
{
   Debug.Log("Hello");
} A derived class (Class B) that derives from Class A includes the following code: public override void Greet ()
{
   Debug.Log("How are you?");
} If only Class B is instantiated and the Greet() method is called, what will appear in the console?   

When an override method is called from a derived class, it completely overrides the parent method. If you also want to inherit the behavior from the parent class, you would need to add a line of code to call that method specifically with: base.Greet();

Which of the following practices are in support of the principle of “encapsulation” in C#?

Using public variables only when necessary

Deactivating objects in a scene that are not in use whenever possible. 

Using events that communicate only to abstract classes.

Which of the following practices are in support of the principle of “encapsulation” in C#? Using getters and setters  Using public variables only when necessary Deactivating objects in a scene that are not in use whenever possible.  Using events that communicate only to abstract classes.  

A major theme of encapsulation is safety in code — in other words, the process of ensuring that code is only used as it is intended to be used, and the values and data you are manipulating can’t be corrupted. In encapsulated code, other programmers can’t easily change the values of variables or the properties of objects. Getters and setters help with this, and so does limiting the number of public variables.

How would you replace the public variable below with a Property, which has improved security and still can be accessed from other classes.


How would you replace the public variable below with a Property, which has improved security and still can be accessed from other classes.
 public int score;    

A property can give access to a private field with the ability to get and set it.

How would you recommend improving the following code in order to improve its reusability?


void DisplayInfo(string name1, string name2, string address1, string address2, string phone1, string phone2)
{
     print(name1);
     print(name2);
     
     print(address1);
     print(address2);
     
     print(phone1);
     print(phone1);

}

How would you recommend improving the following code in order to improve its reusability?
 void DisplayInfo(string name1, string name2, string address1, string address2, string phone1, string phone2)
{
     print(name1);
     print(name2);
     
     print(address1);
     print(address2);
     
     print(phone1);
     print(phone1);

}    

Shorten the variable names to n1, n2, a1, a2, p1, and p2

Use literal strings instead of variables within the print method calls.

Have DisplayInfo return an array composed of all of the strings.

Create new methods for DisplayNames, DisplayAddresses, and DisplayPhoneNumbers, then call each of those methods from DisplayInfo(). 

In general, it is good practice to simplify code by extracting methods that are long or complex into separate methods, then to call those methods from within that method.

 The following is an example of code logic that is very difficult to understand:

public float GetValue()
{
     float result;      
     
     if (bool1)
     {
          result = 1;
      }
      else
      {
         if (bool2)
         {
            result = 2;
         }
         else
         {
            result = 0;
         }
     }
     return result;
 }

True or False: the code below would achieve the same result in a simpler way.

public float GetValue() {
     if (bool1)
     {
         return 1;
     }
     if (bool2)
     {
         return 2;
     }
     return 0; 
}

 The following is an example of code logic that is very difficult to understand: public float GetValue()
{
     float result;      
     
     if (bool1)
     {
          result = 1;
      }
      else
      {
         if (bool2)
         {
            result = 2;
         }
         else
         {
            result = 0;
         }
     }
     return result;
 } True or False: the code below would achieve the same result in a simpler way. public float GetValue() {
     if (bool1)
     {
         return 1;
     }
     if (bool2)
     {
         return 2;
     }
     return 0; 
}    

Code logic should always be easy to evaluate as you read it from top to bottom - the second example eliminates a lot of the unnecessary else statements and achieves the same result.

Which of the following statements about variables is true?

A Property provides public access to a private variable with getters and setters.

Public variables in derived (child) classes cannot be accessed by its base class.

Private variables in base classes are only accessible from derived (child) classes.

Local variables can be accessed from all methods within a single class.

Properties act like variables and encapsulate private member variables. This encapsulation gives you greater control over when and how a variable is accessed or set. You could just make a variable public, but using a property is considered best practice.

When using the profiler to diagnose issues with CPU usage, where would you look to find optimization issues with custom scripts you have written for your application?  

The PlayerLoop is the container of all the code for your Unity application.

Which of the following scenarios is most likely to cause performance issues?

An object with many RigidBodies, each with colliding joints. 

Making a mesh collider convex instead of leaving it in its default state.

RigidBodies that are extremely far away from each other in a scene.

On a complex mesh, using a compound collider made of overlapping box and capsule colliders instead of using a mesh collider. 

While a simple physics joint can be quite fast, the underlying math is very complex. A joint is setting up a system of equations for your Rigidbody’s position, velocity, acceleration, rotation, etc. If you set up something with lots of different Rigidbodies with lots of different joints –all of them colliding, all of them needing to meet the requirements of their joints and not penetrate collision — it can get extremely expensive very quickly.

Unity Version 6.0