For the last couple of weeks, I’ve revisited a couple of the most important concepts of Object Oriented Programming, Polymorphism and Encapsulation. This is my final post for my CS-343 blog entries, and I have decided to continue in this trend. Today’s topic is Abstraction. This week I’ve gone to a favorite resource of mine, geeksforgeeks. Their article on Abstraction covers almost every question that comes up with Abstraction.

I feel it is best to first specify what an abstract class is, and how to make use of one. In Java, an abstract class is defined with the abstract keyword. An abstract class cannot be directly instantiated because of the abstract methods inside the class. An abstract method, is a method that does not have an implementation but must be present in all children classes. This is done via overriding the method(s) in the children classes. Only one method has to be abstract, meaning that there may be other methods that have complete implementations that are reused in their entirety by children classes. Similar to how we implement an interface, we extend abstract classes.

Like my other blog posts, I feel that the best way to learn a concept, is through examples. More importantly, the examples need to be practical, and ones we can relate to. For abstraction, the article on geeksforgeeks uses the classic Shape example that we’re all familiar with.

Our abstract class is the Shape, with three methods and one variable, or attribute. Each Shape has a color, getColor method and two abstract methods, area and toString. A Shape fits exactly into what an abstract class should have, and shows exactly what we can know, based on the object simply being a Shape. A Shape has to have a color, but the formulas for finding the area are different depending on the type of Shape, and the same goes with the toString method.

The children classes presented in the example are the Circle and the Rectangle. The UML from the original article even shows the extends declarator for the children classes. It’s important to note that the abstract methods are not rewritten in each of the children classes. This is because we have to implement them, and thus, they are carried over when we apply the extends declarator. The only new pieces of information in the UML are the attributes we can use for our abstract methods, radius for Circle, and length and width for Rectangle. As seen in the code blocks below the UML, these are used to calculate the area and then the toString.

Abstraction is one of the most important tools that any object oriented developer must have in their toolbox of concepts. This is used in almost every full scale application and often numerous times throughout. A lack of understanding of abstraction will lead to failure to excel in the software engineering world.

Original post here:

http://www.geeksforgeeks.org/abstraction-in-java-2/

From the blog CS@Worcester – Learning Software Development by Stephen Burke and used with permission of the author. All other rights reserved by the author.

For my last blog, I revisited the important concept of polymorphism. For this post, I decided to revisit another important concept, encapsulation. I wanted to find a similarly formatted article/blog post to the one I found for polymorphism, but wanted to get a different perspective from a different resource. I wanted a source that still mixes in code examples,

Let’s start with the definition of encapsulation. Encapsulation is the ability to package data and related behaviors, in an object. This also includes the access permissions for the behaviors within the object. Encapsulation is often used a synonym for data hiding, but it’s important to acknowledge that while encapsulation includes data hiding, this isn’t all that encapsulation is. Everyone thinks of encapsulation as the concept of public versus private variable types. The concept of encapsulation does include this concept, but this is only one area that relates to encapsulation. When creating a new class, encapsulation should be a top priority. This is because with encapsulation, maintainability is drastically increased.

To further explain that encapsulation is not only data hiding, the article uses a classic coding example, an animal class. The class contains several attributes (name, type, height, color) and behaviors (hunt, run, mate, getName). Encapsulation is more than just making sure the attributes are private, it is about bundling the attributes and the related behaviors within one class. We could have the hunt, run, mate, and getName behaviors all in separate classes theoretically, but this would just be poor design. The article also notes that encapsulation is not about getters and setters. While these behaviors are related to the attributes, the authors wanted to make sure readers didn’t confuse encapsulation with this concept. Encapsulation does include getters and setters, but they are not the focus, instead we should focus on the behaviors that return a different value depending on the attribute, instead of just returning the attribute or setting a new value for the attribute.

To explain how I would use this in the future, why not explain how I would expand upon the code example used in the article? This code example in the article only includes hunt, run, mate, and getName for behaviors. If we wanted to add a speak functionality to our animal, we would use encapsulation. This might mean adding a new private variable, but also would include adding a new method that depends on an attribute or several. This behavior and additional attribute(s) would be added to our animal class to encapsulate the data and behaviors, and ensure the best maintainability for our codebase.

I found this article to be simple but powerful. It’s easy to forget that encapsulation is more than data hiding. Encapsulation is one of the major concepts of object oriented programming and complete understanding is necessary for success. I’m sure I’ll get interview questions regarding this topic in the future.

The original article: https://javapapers.com/core-java/java-encapsulation/

From the blog CS@Worcester – Learning Software Development by Stephen Burke and used with permission of the author. All other rights reserved by the author.

Before this class, I had heard of Angular before and had always heard it referred to as a JavaScript framework. I guess technically it is, because it still compiles to JavaScript but the language itself is written in the JavaScript superset, TypeScript. I had never heard of TypeScript before this class and the idea of a superset language was also a new concept. I was curious why Angular was written in TypeScript over JavaScript or other supersets. I know from outside sources that the first iteration of Angular was written in JavaScript but every iteration of the framework since, has been written in TypeScript and I wanted to know why. This post by Victor Savkin lays out the benefits of using TypeScript as a way of explaining why Google chose TypeScript for Angular.

Victor clears up my lack of understanding of what a superset is relatively simply. He explains that being a superset of JavaScript, everything you can do in JavaScript, you can do in TypeScript. With small changes to the code, a “.js” file can be renamed a “.ts” file and compile properly.

Victor emphasizes the lack of scalability in vanilla JavaScript. With JavaScript, large projects are much more difficult to manage for many reasons including the weakly typed aspect and the lack of interfaces. TypeScript solves these problems and helps create better organized code with its syntax. With its better organization, TypeScript is much easier to read through compared to JavaScript.

The lack of interfaces in JavaScript is a major reason why it doesn’t scale well for large projects. Victor uses a code example in JavaScript that shows that aspects of a class can be lost in JavaScript because of its lack of explicitly typed interfaces. The code is then reshown in TypeScript and is much more clear because you can actually see the interface. It’s that simple, in JavaScript, you have to really focus in on how every object interacts with each other because of the lack of explicitly typed interfaces. TypeScript allows you to create these interfaces so future code maintenance is less stressful and bug filled.

TypeScript offers explicit declarations, which is illustrated through some code samples in the article. The JavaScript code is a simple function signature that lacks any typing or clear information about the variables involved in the function. In the TypeScript version, it is clear what the types of the variables are, making the function much more clear in TypeScript.

There are other reasons defined in this article on why TypeScript was chosen and what makes it so great, but these are a few of the ones that stuck out to me. I’ve written JavaScript projects before and wondered how some of these concepts would affect larger projects, and now I know how they can be resolved. This article and information will prove useful for writing my final project and any future TypeScript-based projects that I decide to take on in the future.

Original Post: https://vsavkin.com/writing-angular-2-in-typescript-1fa77c78d8e8

From the blog CS@Worcester – Learning Software Development by Stephen Burke and used with permission of the author. All other rights reserved by the author.

This week I found this article on JavaWorld by Jeff Friesen that is entirely about polymorphism. Polymorphism is a core concept for all software development and a lack of strong understand will lead to weak applications and poorly written code. One can never revisit topics like polymorphism too much. This article discussing the four types of polymorphism, upcasting and late binding, abstraction, downcasting, and runtime type identification (RTTI). The article presents everything in the form of a code example and constantly revisits in the explanation process, which I find incredibly useful.

The first part of the article is an overview of the four types of polymorphism, coercion, overloading, parametric and subtype.. Of these four there are some bits that stuck out more to me than others. For coercion the obvious example is when you pass a subclass type to a method’s superclass parameter. At compilation, the subclass object is treated as the superclass to restrict operation. The simple example that is forgotten is when you perform math operations on different “number” data types like int’s and floats. The compiler converts the int’s to float’s for the same reason as the subclass to superclass object. Another piece in this first section that stood out to me was the overloading type of polymorphism. The obvious example here is overloading methods. In a class, you can have different method signatures for the same method name and each will be called depending on the context. Again, there is a simple example that is overlooked in the operators like “+”. For example, this operator can be used to add int’s, float’s, and concatenate Strings depending on the types of the operands.

The upcasting section uses our favorite example, different types of shapes and is almost entirely written in reference to one line of code, Shape s = new Circle(); This upcasts from Circle to Shape. After this happens, the object has no knowledge about the Circle specific methods and only knows about the superclass, Shape methods. When a shared method (implemented in both Shape & Circle), the object is going to use the Shape implementation as well unless it is clear through context to use Circle’s.  Similar to this section that uses superclasses and subclasses, is the section on abstraction. The article uses the Shape and Circle example again but points out that having a draw() method that does something in Shape does not make any sense from a realistic standpoint. Abstraction resolves this, meaning that in an abstract class, there is no way to instantiate a method like draw() for the superclass of Shape. This also means that every abstract superclass needs subclasses to instantiate their behaviors.

These are just a few parts of the article that stood out to me personally. The article as a whole is incredibly useful and worthy of a bookmark by every developer. I will continue to revisit this article if I find myself lacking confidence about the topic of polymorphism in the future!

Original Article: https://www.javaworld.com/article/3033445/learn-java/java-101-polymorphism-in-java.html

From the blog CS@Worcester – Learning Software Development by Stephen Burke and used with permission of the author. All other rights reserved by the author.

This week I decided I wanted to read a blog post as opposed to a podcast for my blog entry. I went to the slack channel and found an article posted by Jason Knowles on writing clean code. Before reading the article, I knew had a general idea of what clean code was supposed to be, but lacked depth in understanding. Clean code is tremendously important in becoming a strong software engineer. Without a good understanding of writing clean code, a developer will never be successful in effectively contributing to a team. My goal and reasoning for choosing this blog post was to get a better idea of what clean code is exactly and how to work towards consistently writing it.

The blog post opens up a general overview of what clean code is and it’s importance in software maintenance. This flows into the main portion of the post, which is the practices to follow to ensure that one’s code is clean. The post ends with a few sections about code review, pair programming, and other resources.

One of the areas in the post that stuck with me the most is the topic of methods/functions performing a single operation. If a method performs multiple operations, it is probably a good idea to split this method into two different calls. This concept relates to the idea further discussed in the post about inline code VS function calls. The writer identifies that there isn’t one perfect solution for every given problem. In some scenarios, inline code is a better solution than creating a function/method to solve an operation. What comes to mind immediately to me is situations where a few operations will clearly never be needed elsewhere in the application and writing a longer method/function once will make future maintenance and understanding easier. The scenarios where method calls are better seems to be the vast majority of the time.  

Another area in the post that caught my attention is the area regarding comments. The writer discusses the idea that comments are often a sign of poor code. This caught me off guard as I’ve always used comments as a way to remember what a function does for future additions and changes to my applications. The author writes that “comments should explain where code cannot” and that comments should be used to explain unconventionally written code. From reading the rest of article, it seems that if the code is written unconventionally, the comments are still a cover-up for poorly written code. This may be a poor code base that the current developer is simply writing an addition to, but does not have time to fix a poor code base.

In my first couple of years as a CS major, I have struggled with writing clean code and I feel that this article will help me in the future to write, scalable, easy to maintain code.

For anyone interested, here is the article this post is about.

https://www.thecodingdelight.com/write-clean-code/#ftoc-heading-2

From the blog CS@Worcester – Learning Software Development by sburke4747 and used with permission of the author. All other rights reserved by the author.