Udacity Kotlin Nanodegree: Course 1

I have been waiting for this course to come out for the past six months and now it is here! I was able to get a 50% off on the course so that was really helpful. So far, the course has been amazing and I have built my first app, a dice roller!

You can check it out here. https://github.com/esegebart/diceroller

This is what I have learned in my first course. I am posting this as reference to myself later.

Namespaces – tools – define dummy content that is only used when you preview the app in the preview pane

Attr using the namespace tools will be gone when the app compiles

Two namespaces at top: tool and android. Android is part of the core framework.

Gradle determines what devices can run your app, compiles app to executable, handles dependency management, automated testing, and app signing for Google play. Gradle packages your app into an apk with its resources, compiled code, Android manifest, etc and then transfers the apk to your emulator or device.

There are two Gradle files: build.gradle (project) and build.gradle (app). The app gradle file handles your different modules that has different functionalities, libraries, and supporting android wearables. In larger apps, each module will have its own gradle file. Inside the Gradle project file, there are repos that are available to the whole project: google() and jcenter().

Gradle also handles all the dependencies which is external code and libraries a project depends on. These are handled in the dependencies block.

dependencies {

           dependencies are managed here

           app dependencies do not go here

}

The app folder gradle file configures how to set up the app module and deals with the plugins to run and build Android and kotlin projects. This also tells the app the compilesdk, targetsdk, and minsdk. These are pretty straighforward. Min is the minimum version it can run on. The target will always match the compilesdk. This also has the appID which is a unique identifier and necessary for Google Play. It is the domain your app is hosted on, reversed, followed by the app name. So if my app was hosted on elyse.com and my app is named diceroller, it would be com.elyse.diceroller. This is set up when the project is started.

The version level you lists matches to an API level, and all api levels are named after tasty treats.

ANDROID JETPACK is the new android support libraries – androidx – and has all the support libraries for new and old apis.

APPCOMPATACTIVITY – The main activity extends from this. It is a compatibility class that makes sure activity includes a menu bar (action bar) that looks the same across OS levels and is a part of androidx. I never knew exactly what this was, so this was helpful.

Adding Vector Drawables: The proper way to use vector drawables and keep compatibility with older versions of android is followed.

  • In Gradle build.app file – under default config add vectorDrawables.useSupportLibrary = true.
  • Add app:srcCompat=”@drawable/image_name” in the ImageView tag
Add the namespace to the root of the layout xmlns:app="http://schemas.android.com/apk/res-auto"
  • This is using the support library to reference the image resource in the layout file and enable the support library for vector drawables in the app level build.gradle
  • THIS OPTIMIZES APP SIZE ON OLDER PLATFORMS
  • Open drawable (dice.xml) to see the colors and shapes listed in xml

build.gradle app file will generate png files that are use on those devices that are below minsdk. Png files will make app larger and make it slower. Large apps have high chance of being uninstalled. Androidx compat library supports devices all the way back to api level 7.

Adding app namespace supports either custom code or libraries in your project and not core android libraries.

Dependencies required to build the project or enable additional functionality are defined in the build.gradle.

Basic app structure:
Layouts – xml files the define what your app will look like
Activites – Kotlin classes where you write the dynamic parts of your app
Layouts and activities are connected by the process of layout inflation – and finding view objects by their unique id
TextView – displays text to the user
ImageView – display images to the user
Images are a drawable resource type.

Build gradle project in command line:
Change the directory of your project.
Type gradle run.
You can also include gradle run –warning-mode=all to see specific warnings.
Or you can type gradle tasks –info. Shows all tasks and what they are doing.

Clean Code: Naming Conventions

A series of blog posts based on Robert C. Martin’s book “Clean code : a handbook of agile software craftsmanship“.

You can find the book here.

As a programmer, we are going to be naming lots of variables, classes, and methods. According to Uncle Bob in Clean Code, we should name a variable with the same care we do in naming a first-born child. After all, we are going to need to be able to call it, know what it’s for, and not confuse it with any other variables in our classes.

When we name with care, we name with “intention-revealing” names. Naming well saves you more time in the long run, saves everyone more time, and prevents a snowball of bad things happening to your precious code. The names we choose should answer the big questions:

Why does it exist?
What does it do?
How is it used?

Good and bad naming examples in code.

We need to be able to tell what the code is doing. In the example picture, it is very easy to see what the purpose is of the last three names versus the first name. Explicit names help immediately see what is going on in the code. If you MUST use a single letter name, it is best practice to use it as a local variable inside a short method. The length of a name should correspond to the size of its scope.

Using a name like h, we would have to mentally map what this variable is doing, translating it in our brain to what it actually does, using much more memory. Clarity is king. Use your powers for good naming practices to write code that everyone can understand. Pretend like the next person who will read your code is a violent psychopath who knows your address. It’s serious business!

Class and Method Names

This is something that needs to be written on your computer or tattooed on your arm or put anywhere you can see it, like an affirmation you are practicing, only programmer edition.

Photo by ThisIsEngineering on Pexels.com

Class names should have a noun or noun phrase. Class names should not be verbs.

Methods should have verb or verb phrases. Accessors, mutators, and predicates should be named for their value and prefixed with get, set, and is according to the javabean standard.
(“Oracle Java Technologies | Oracle,” 2019).

Don’t be cute in naming. Clever names are memorable only to people who share the same humor and some of us are the only ones laughing at our jokes. I know I’m funny, but others may not think so. Clarity is more important than entertainment. Our cleverness only goes so far as our cultural slang. Naming something dirtNap() meaning kill() or wipeout() meaning DeleteItems() is cute, but the latter is understood by all. A consistent lexicon is worth its weight in gold for the programmers who must use your code.

Other Important Naming Concepts

Pick one word for an abstract concept and stick with it. Using fetch, retrieve, and get as similar methods in different classes goes back to using too much mental memory. Ask yourself some questions about what these methods are doing and see if they are all serving the same purpose to choose an appropriate word.

Don’t Pun. Converse to using one word per abstract concept, do not use the same word for two purposes. Doing so would be a pun. Using “one word per concept”, could end up with a lot of classes using an “add” method as described in the book. If we are using the word for consistency rather than intent, it can get very confusing. Ask yourself what the method is actually doing so you know if you need to name it “insert” or “append”.

Use Solution Domain Names. Programmers will be reading your code so go ahead and use terms that other programmers understand like algorithm names, math terms, and pattern names.

Use Problem Domain Names. Problem domains refers to all the information that defines the problem (i.e. the problem you are solving with code). If there are no programming or computer science terms for what the code is doing, use the name from the problem domain. Good programmers and designers have the important task of separating solution and problem domain concepts.

Photo by Startup Stock Photos on Pexels.com

Add Meaningful Context, But Not Gratuitous Context. Most of the time we have successfully added meaningful context by using good naming, separation of concerns, and well-defined classes. As a last resort, you may have to add some prefixing. If you saw firstName, lastName, street, houseNumber, city, state, and zipcode in a method, you would assume it’s an address. If city was used alone in a method, would you assume it’s part of an address? The context can be added by prefixing with addrState, addrCity, etc so it’s explicitly part of an address.

This doesn’t mean to do this always. Adding gratuitous context can be very confusing, like prefixing every method with the acronym of the application. “ABCFirstName, ABCLastName, ABCStreetAddress” are too much. Shorter names are generally better than long ones when they are clear.

Following some of these rules and asking yourself the important questions about your code will help get you thinking about what and why you are naming things and keeping the code understandable for all, saving you many headaches in the future. Happy coding!

References:

Oracle Java Technologies | Oracle. (2019). Retrieved March 29, 2020, from Oracle.com website: https://www.oracle.com/java/technologies/

Martin, R. C. (2009). Clean code: A handbook of agile software craftsmanship. Upper Saddle River, NJ: Prentice Hall.