Abstraction in object-oriented programming

Inheritance and polymorphism in object-oriented programming

Encapsulation in object-oriented programming

Profile code to identify issues

Job preparation: Junior Programmer

Quiz: Apply object-oriented principles

Submission: Programming theory in action

Deep-dive into the pillars of object-oriented programming and their application, then learn how to profile and optimize code.

In this mission, you’ll refactor the inventory project you completed in the previous mission using the pillars of object-oriented programming as a guide. You’ll deep dive into the inner workings of each pillar individually, so you can better understand its value in developing applications. Next, you’ll learn how to profile your code to identify any optimization bottlenecks that would slow down the final build of your application. To close out this mission, you’ll develop a small application for your portfolio that uses fully optimized code built on OOP principles. 

When you complete this mission you will complete the Junior Programmer pathway - CONGRATULATIONS!

Apply Object-Oriented Principles

Unity Junior Programmer

Kickstart your programming career with Unity's Junior Programmer Pathway. Learn coding fundamentals, C#, and game development to create your first interactive projects. Start learning for free!

Junior Programmer Pathway - Learn Coding & Game Development | Unity Learn

We recommend that you have basic knowledge of Unity or complete 

Ready to code? This guided learning Pathway will take you from zero to job-ready!

Welcome to Junior Programmer! Designed for anyone interested in learning to code or obtaining an entry-level Unity role, this pathway assumes a basic knowledge of Unity and has no math prerequisites. Junior Programmer prepares you to get Unity Certified so that you can demonstrate your job-readiness to employers.

Junior Programmer

Course Introduction

Install Unity Software

Unit 1 - Introduction

Lesson 1.1 - Start your 3D Engines 

Lesson 1.2 - Pedal to the Metal

Lesson 1.3 - High Speed Chase

Lesson 1.4 - Step into the Driver's Seat

Challenge 1 - Plane Programming

Lab 1 - Project Design Document

Introduction to project management and teamwork

Quiz 1

Learn how to create new C# scripts, call basic functions, and use variables to modify the results of those functions.

In this first mission in the Junior Programmer pathway, you will program a car moving side-to-side on a floating road, trying to avoid (or hit) obstacles in the way. In addition to becoming familiar with the Unity editor and workflow, you will learn how to create new C# scripts and do some simple programming. By the end of the Unit, you will be able to call basic functions, then declare and tweak new variables to modify the results of those functions.

Player Control

Unit 2 - Introduction

Lesson 2.1 - Player Positioning

Lesson 2.2 - Food Flight

Lesson 2.3 - Random Animal Stampede

Lesson 2.4 - Collision Decisions

Challenge 2 - Play Fetch

Lab 2 - New Project with Primitives

Quiz 2

Mod the Cube

Quiz: Create with Code 1

Gain familiarity with some of the most important programming and Unity concepts, including if-then statements, random value generation, arrays, collision detection, prefabs, and instantiation.

In this Mission, you will program a top-down game with the objective of throwing food to hungry animals - who are stampeding towards you - before they can run past you. In order to do this, you will become much more familiar with some of the most important programming and Unity concepts, including if-then statements, random value generation, arrays, collision detection, prefabs, and instantiation. In completing this Unit, you will learn how to program a basic game with the ability to launch projectiles and maneuver the player to keep the game alive.

Basic Gameplay

Unit 3 - Introduction

Lesson 3.1 - Jump Force

Lesson 3.2 - Make the World Whiz By

Lesson 3.3 - Don't Just Stand There

Lesson 3.4 - Particles and Sound Effects

Challenge 3 - Balloons, Bombs, & Booleans

Lab 3 - Player Control

Quiz 3

Learn how to add music, sound effects, and visual particle effects to transform the experience of your project.

In this Mission, you will program a fast-paced endless side-scrolling runner game where the player needs to time jumps over oncoming obstacles to avoid crashing. In creating this prototype, you will learn how to add music and sound effects, completely transforming the experience of your projects. You will also learn how to create dynamic endless repeating backgrounds, which are critical for any side-scrolling games. Finally, you will learn to incorporate particle effects like splatters and explosions, which make your games so much more satisfying to play.

Sound and Effects

Unit 4 - Introduction

Lesson 4.1 - Watch Where You’re Going

Lesson 4.2 - Follow the Player

Lesson 4.3 - PowerUp and CountDown

Lesson 4.4 - For-Loops For Waves

Challenge 4 - Soccer Scripting

Lab 4 - Basic Gameplay

Quiz 4

Learn how to implement new gameplay mechanics including powerups and increasing difficulty.

In this Mission, you will program an arcade-style Sumo battle with the objective of knocking increasingly difficult waves of enemies off of a floating island, using power ups to help defeat them. In creating this prototype, you will learn how to implement new gameplay mechanics into your projects, which are new rules or systems that make the game more interesting to play. On one hand, you will learn to program a powerup, which give the player a temporary advantage. On the other hand, you will learn to program increasingly difficult enemy waves, which make survival more challenging for the player. A good balance of powerups and increasing difficulty make for a much more interesting gameplay experience.

Gameplay Mechanics

Unit 5 - Introduction

Lesson 5.1 - Clicky Mouse

Lesson 5.2 - Keeping Score

Lesson 5.3 - Game Over

Lesson 5.4 - What’s the Difficulty?

Challenge 5 - Whack-a-Food

Lab 5 - Swap out your Assets

Quiz 5

Introduction to user feedback and testing

Learn how to implement a User Interface - or UI - into your projects, such as a title screen and score display.

In this Mission, you will program a game to test the player’s reflexes, where the goal is to click and destroy objects randomly tossed in the air before they can fall off the screen. In creating this prototype, you will learn how to implement a User Interface - or UI - into your projects. You will add a title screen with a difficulty select menu that will control how challenging the gameplay is, you will add a score display that will track how many points the player has earned, and you will add a Game Over screen, which will allow the player to restart and try again. In learning these skills, you will be able to create a fully “playable” experience that the user can enjoy from start to finish without having to restart the application to try it again.

User Interface

Next Steps - Introduction

Lesson 6.1 - Project Optimization

Lesson 6.2 - Research and Troubleshooting

Lesson 6.3 - Sharing your Projects

ECS Survival Guide

Career research and preparation

Introduction to portfolios

Debug the App

Counting Prototype

Quiz: Create with Code 2

Prepare to continue developing your Unity and C# skills independently, including learning how to complete your personal project.

In this Mission, you'll prepare to continue developing your Unity and C# skills independently, including learning how to complete your personal project and how to prepare for the Unity Certified User: Programming exam, which you can take through your school program, if available.

Publishing Your Project

Introduction to real-time 3D experience design

Set up version control

Explore the sample project

Principles of object-oriented programming

Create a scene flow

Implement data persistence between scenes

Implement data persistence between sessions

Quiz: Manage scene flow and data

Submission: Data persistence in a new repo

Learn about data persistence and an introduction to the core pillars of object-oriented programming.

In this mission, you’ll learn about data persistence, or how to manage the loading and unloading of data between both scenes and sessions. Along the way, you will be introduced to the core pillars of object-oriented programming, which will help you structure your code throughout the mission. There will only be one practical example throughout the mission, which will build on the new functionality you create with each tutorial. At the end of this mission, you’ll take everything you learned and apply it to a new project by building a persistent score system for a small game.

Manage Scene Flow and Data

d6f60a1d-e2ea-4360-9bca-140997e92813:5f0f96e81e47

Overview

What is Abstraction?

Abstraction and script refactoring

Implementing abstraction in the project

Summary

In this tutorial, you’ll learn about the first pillar of object-oriented programming: Abstraction. 

By the end of this tutorial, you will be able to:

Explain how abstraction is used to expose only necessary script components  

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

Designed for post-secondary and K-12 educators at accredited academic institutions teaching Unity in the classroom, the Unity Educator plan provides you with free access to the same real-time 3D development tools used by professionals to support your students.

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Junior Programmer Pathway Facilitator Kit.zip

Junior Programmer Pathway Facilitator Kit (Google Drive)

Unity Educator Hub

The Unity Junior Programmer Pathway Facilitator Kit includes everything you need to successfully bring this Pathway into your learning context including a syllabus, complete lesson plans, standards alignment, teacher preparation guide, and more. 

Junior Programmer: Apply object-oriented principles

We are ready to work through our existing code and improve it without changing its external functionality — a process called refactoring. Refactoring is an important step in the development process, in which you can clean up any messy code you wrote earlier, and also reexamine the ways your code will be used in future iterations of the project. In other words, in the development phase you wrote code that “works well for now,” and in the refactoring phase you will revise the code to “work well later.”

In the last mission, we introduced the concept of object-oriented programming, and throughout the Junior Programmer Pathway you’ve been implementing some of its best practices. Now, you’ll examine each of the principal pillars (abstraction, inheritance, polymorphism, and encapsulation) in depth, and use the paradigm as guidance to effectively refactor your code, beginning with abstraction.

As you work through this final mission, you’ll continue refining the inventory project that you built in the previous mission.

The first pillar of OOP is all about keeping your code clean and simple for the programmer using it, whether that is you or someone else. Abstraction is the process of removing complex code from the scripts where other programmers will see it, and only exposing the functionality other programmers really need. When you “abstract out” the details, you reduce duplicate code and provide easy access to the most useful functions. You’re actually already quite familiar with this pillar, because you’ve benefited from it frequently throughout this pathway. Whenever you call on a method to perform a task rather than writing out all of the code by hand, you’re benefiting from abstraction! 

Let’s take a look at a situation where you already used abstraction. During Create with Code. In Unit 4 - Gameplay Mechanics, you created some functionality to spawn an enemy wave.

When you initially wrote the code, you put it in the Start method: 

private void Start()
{
    for (int i = 0; i < 3; i++)
    {
        Instantiate(enemyPrefab, GenerateSpawnPosition(),   
        enemyPrefab.transform.rotation);
    }
}

Since Start only runs once when the game loads, if you wanted to spawn another enemy wave, you’d have to paste that line of code elsewhere in your script where you wanted it to occur. Having to constantly rewrite (or copy and paste) the same lines of code over and over is inefficient and prone to error. It also means that later refactoring becomes difficult, as you have to search throughout all of your scripts and rewrite all the references over again. 

Instead, you separated out the spawning functionality into its own method, and called that on Start: 

void SpawnEnemyWave() // create new higher-level method 
{
    for (int i = 0; i < 3; i++)
    {
        Instantiate(enemyPrefab, GenerateSpawnPosition(), 
        enemyPrefab.transform.rotation);
    }
}

private void Start()
{
    SpawnEnemyWave(); // call higher-level method in Start()
}

You created a higher-level, more “abstract” function called SpawnEnemyWave. You were then able to spawn enemies anywhere in your script from a single line of code. And, if you needed to refactor it later, you could do it in a single location. Additionally, you and your fellow programmers no longer need to worry about the specifics about how the enemies are being spawned. All that matters is the more abstract concept: if you call SpawnEnemyWave(), they will be spawned.

Your experience with abstraction isn’t limited to methods of your own creation. In fact, you’ve been benefiting from abstraction every time you call on a method built into Unity:

rb.AddForce(Vector3.up * Random.Range(12, 16), ForceMode.Impulse);

Adding force to a RigidBody involves a great deal of mathematics interacting with the physics system. However, since Unity has provided you with this simple “abstract,” high-level function (AddForce), you need only call the AddForce method, and give it the parameters that are relevant to your needs. You don’t even need to understand Unity physics to successfully add force to your object!

Image of four pillars in a row, labeled from left to right with Abstraction, Inheritance, Polymorphism and  Encapsulation. The first pillar labeled Abstraction is highlighted.

Image of gameplay from the “Sumo Battle” prototype made in Create with Code Unit 4. On a floating island, there are 3 white spheres (the enemies) and one black sphere (the player).

Remember that an important part of refactoring code is to improve its functionality without changing the way that other programmers interact with it. Abstraction plays a key role in this! As long as the method call and output doesn’t change, you can adjust the contents of the method without the other programmer ever knowing. This means that you can safely refactor your code without risk of breaking anything elsewhere in your project. 

int TripleResult (int inputNumber)
{
    int outputNumber = inputNumber + inputNumber + inputNumber;
    return outputNumber; 
}

In the above method, the calling script passes in an integer and gets an output that’s been tripled. The approach to get the output number is a little ineffective, so you could refactor the code to look like the following 

int TripleResult (int inputNumber)
{
    int outputNumber = inputNumber * 3;
    return outputNumber;
}

Even though the content of the method has been rewritten, the way the method is called remains exactly the same, as does what gets returned. Therefore, any call to the method throughout the project will continue to work.

Let’s implement the abstraction principles we just learned by refactoring UserControl in the inventory project. All of the functionality involved with selecting the Forklift and moving it to the desired resource is in the Update method. But what if, later on, we want other factors to be able to control these selections and actions? Let’s abstract that functionality out into two new methods to make that possible.

1. If needed, open the Inventory project from the previous mission.

2.  Locate the UserControl script in the Scripts folder and open it in Visual Studio. 

3.  Above Update, define two new public methods with no returns and name them HandleSelection and HandleAction. 

public void HandleSelection ()
{

}

public void HandleAction ()
{

}

HandleSelection will manage everything that occurs when the user left-clicks one of the Forklifts in the application. We’ll still need to check for the left mouse button (Input.GetMouseButtonDown(0)) in Update, but everything else will be moved to our new method. 


4.  In the Update method, select the contents of the if(Input.GetMouseButtonDown()) statement and move it to HandleSelection. 

public void HandleSelection()
{
    // start of code cut from GetMouseButtonDown(0) check
    var ray = GameCamera.ScreenPointToRay(Input.mousePosition);
    RaycastHit hit;
    if (Physics.Raycast(ray, out hit))
    {
        // the collider could be children of the unit, so we make sure to check in the parent
        var unit = hit.collider.GetComponentInParent<Unit>();
        m_Selected = unit;


        // check if the hit object have a IUIInfoContent to display in the UI
        // if there is none, this will be null, so this will hid the panel if it was displayed
        var uiInfo = hit.collider.GetComponentInParent<UIMainScene.IUIInfoContent>();
        UIMainScene.Instance.SetNewInfoContent(uiInfo);
    }
    // end of code cut from GetMouseButtonDown(0) check
}

private void Update()
{
    // ...

    if (Input.GetMouseButtonDown(0))
    {
        // code cut from here  
    }
    
    // ... 
}

5.  In the if(Input.GetmouseButtonDown()) statement, call HandleSelection(); 

if (Input.GetMouseButtonDown(0))
{
    HandleSelection(); // method now called from here   
}

Now let’s repeat this process for HandleAction().


6.  In Update, locate the else if (m_Selected != null && Input.GetMouseButtonDown(1)) statement, and move its contents to HandleAction(). 

public void HandleAction()
{
    // start of code cut from GetMouseButtonDown(1) check
    var ray = GameCamera.ScreenPointToRay(Input.mousePosition);
    RaycastHit hit;
    if (Physics.Raycast(ray, out hit))
    {
        var building = hit.collider.GetComponentInParent<Building>();

        if (building != null)
        {
            m_Selected.GoTo(building);
        }
        else
        {
            m_Selected.GoTo(hit.point);
        }
    }
    // end of code cut from GetMouseButtonDown(1) check
}


private void Update()
{
    // ...

    else if (m_Selected != null && Input.GetMouseButtonDown(1))
    {
        // code cut from here 
    }

    // ...
}


7.  In the else if (m_Selected != null && Input.GetMouseButtonDown(1)) statement, call HandleAction(). 

else if (m_Selected != null && Input.GetMouseButtonDown(1))
{
    HandleAction(); // method now called from here  
}

8.  Save the script and return to Unity and playtest the scene. 

The functionality shouldn’t have changed: you should be able to left-click on a Forklift and right-click on a resource pile, and the Forklift should transport resources exactly as before. The difference now is that if you or any other programmer needs this functionality elsewhere in the application later, it’s more freely available. 

Abstraction simplifies your code and keeps it clean, making it easier for programmers to use. The core tenet of abstraction is to hide unnecessary complexity from the other programmers, and only expose what is needed to make the code run as it’s meant to. It means taking the complex inner workings and replacing them with abstract, more reusable pieces of code.  Following this principle also simplifies the process of refactoring later. Now that you’ve learned how to apply abstraction to the inventory project, think about how you might be able to apply it to your own applications, or even try to do it! 

Abstraction in object-oriented programming

1. Overview

2. What is Abstraction?

3. Abstraction and script refactoring

4. Implementing abstraction in the project

5. Summary

Complete this tutorial