Techorama This Week – Kotlin, C#, Flux, Design Patterns, and more!

If you’re in the Netherlands this week, come catch me at Techorama! I’ll be there from the 30th through the 3rd of October and presenting two different sessions:

techorama_sessions

On the 1st, I’ll be speaking on Kotlin for C# Developers:

Dive into the latest craze in languages and platforms – Kotlin. This time we will be looking at it from the perspective of a .NET C# developer, draw comparisons between the languages, and bridge the gap between these 2 amazing languages. We’ll look at: – Kotlin as a language – Platforms Kotlin is great for – Object Oriented Implementations in Kotlin – Extended Features – Features Kotlin has that C# doesn’t – A demo Android application in Kotlin vs a Xamarin.Android app in C# In the end you will leave with a foundational knowledge of Kotlin and its capabilities to build awesome apps with less code. You should feel comfortable comparing C# applications to Kotlin applications and know where to find resources to learn even more!
And on the 2nd I have another morning session on implementing the Flux design pattern in C# and .NET:
Learn about the Flux design pattern and how to implement it in your C# client applications like UWP, Xamarin, and all the other platforms .NET is touching now. We’ll compare Flux and Uni-Directional data flows to the existing tools and directions development takes us in C# client apps and talk about all the pros and cons that come with both. We’ll take an existing Xamarin.Forms app using MVVM and “Flux it Up” to migrate to a more 1-direction flow of data and actions. When you leave, you’ll have a solid understanding of Flux and some of its existing implementations such as Redux and be confident in implementing it yourself in C#!

Pre-conference Meetup

If you’re not going to Techorama this year, but are still in the area, you can find me tomorrow at the Dutch Mobile .NET Developers meetup with some of the other amazing people from the Xamarin and .NET Community. I’ll be on a panel talking about mobile technologies and practices!

2019 Meetup – Xamarin with David Ortinau & Mobile Expert Panel

Monday, Sep 30, 2019, 6:00 PM

Info Support
Kruisboog 42 Veenendaal, NL

50 Code monkeys Attending

18:00 Doors open & Dinner 19:00 – 20:00 *The Latest and Craziest for Mobile .NET Developers* David Ortinau @davidortinau Microsoft has been hard at work improving Visual Studio and Xamarin for mobile developers. I’ll demo the latest features you can use to make your dev experience better today. And in the future? Microsoft has some “coming soon” as…

Check out this Meetup →

 

Here’s the schedule:

18:00 Doors open & Dinner
19:00 – 20:00 The Latest and Craziest for Mobile .NET Developers
David Ortinau @davidortinau
Microsoft has been hard at work improving Visual Studio and Xamarin for mobile developers. I’ll demo the latest features you can use to make your dev experience better today. And in the future? Microsoft has some “coming soon” as well as highly experimental projects that are “must see”!

20:00 – 20:15 Break
20:15 – 21:00 Mobile Expert Panel with Alex, Brandon, Dan & Gerald
Open Q&A for these mobile experts that have absolutely made their mark in the mobile developer space. This is your chance to ask anything you’d like! Joining us are:

Alex Dunn @suave_pirate
Author at Pluralsight | Xamarin MVP | Microsoft MVP

Brandon Minnick @thecodetraveler
Microsoft Developer Advocate | Mobile App Developer

Dan Siegel @danjsiegel
Microsoft MVP | @PrismLib Maintainer | Xamarin Evangelist | @XamDevSummit Organizer

Gerald Versluis @jfversluis
Engineer @Microsoft for #XamarinForms | Former Microsoft MVP

21:00 Drinks & Closing

 

See ya’ll there!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

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HACKMIT 2019 This Weekend!

HackMIT is this weekend, September 14-15th.

I’m happy to announce that I’ll be mentoring as one of the local Microsoft MVPs that were invited to help as part of the Microsoft sponsorship of the event. I look forward to building some incredible applications with some of the brightest students coming to Cambridge! Hack for a reason 🙂

Check out some of the awesome tracks:

hackmit_tracks

 

If you’re hacking this weekend, come find me for help with:

  • Conversational AI
  • Voice First Development
  • Azure
  • AWS
  • Machine Learning
  • Unity
  • C#
  • JavaScript/TypeScript
  • Kotlin
  • React
  • Video Editing
  • and RTC

See ya’ll there!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Video – Kotlin for C# Developers at NDC Oslo

In June, I had the amazing privilege of giving a talk at NDC Oslo called “Kotlin for C# Developers”! Lucky for you, NDC records all of their sessions, so you can check out the recording from YouTube right here 🙂

Dive into the latest craze in languages and platforms – Kotlin. This time we will be looking at it from the perspective of a .NET C# developer, draw comparisons between the languages, and bridge the gap between these 2 amazing languages.

We’ll look at:
– Kotlin as a language
– Platforms Kotlin is great for
– Object Oriented Implementations in Kotlin
– Extended Features
– Features Kotlin has that C# doesn’t
– A demo Android application in Kotlin vs a Xamarin.Android app in C#

In the end you will leave with a foundational knowledge of Kotlin and its capabilities to build awesome apps with less code. You should feel comfortable comparing C# applications to Kotlin applications and know where to find resources to learn even more!

Let me know your thoughts in the comments or on Twitter, and check out my other content on Kotlin here: https://alexdunn.org/tag/kotlin/

Want to see this live? I’ll be giving an updated version of this talk at Techorama Netherlands in September/October along with an introduction to the Flux design pattern in C#.

Check those out here:

If you prefer to just jump right into a language / platform – I would happily suggest my Pluralsight course – Building Android Apps with Kotlin: Getting Started. Take a look here: https://app.pluralsight.com/library/courses/building-android-apps-kotlin-getting-started/

 

 


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile and AI developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.


voicify_logo
I’m the Director and Principal Architect over at Voicify. Learn how you can use the Conversation Experience Platform to bring your brand into the world of voice on Alexa, Google Assistant, Cortana, chat bots, and more: https://voicify.com/


NDC Oslo Coming Up!

Just a quick post today to tell you all how excited I am for the next event I’ll be at:

NDC, one of my absolute favorite conference series is going to be running their original NDC Oslo conference in the next couple weeks! As always, I’m so humbled to be among some of the most amazing people in the Software industry that I personally have learned so much from. I hope to be able to share my experiences and learnings with you all in return!

I’ll be speaking about two of my favorite programming languages, Kotlin and C#! If you’re a C# developer and are interested in learning more about Kotlin and what’s been going on with one of the hottest new languages, come check out my session where we will intro Kotlin, compare features of the language, and even talk about how they might play well together in the future! If you don’t come for the languages, come for the stickers! I’m coming in hot with some awesome Kotlin, Xamarin, and C# stickers.

If you aren’t coming to NDC Oslo, be sure to check out my Kotlin posts here as well as check out my course on Pluralsight – Building Andorid Apps with Kotlin: Getting Started to learn about how to apply Kotlin to building native Android apps with the latest and greatest tools!

You can also checkout an older version of my Kotlin for C# Developers talk from NDC London here. https://www.youtube.com/watch?v=pR8zPYlNU0k

Can’t wait! See you there!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Kotlin for C# Developers – Asynchronous Programming

Series Introduction

With my recent work in Kotlin in the last few years and my continuing work in C# throughout my entire professional career, I’m often asked to compare the two languages. This sparked the creation of my latest conference session – Kotlin for C# Developers.

The next time I’m giving this talk is at NDC London – https://ndc-london.com/talk/kotlin-for-c-developers/

But I figured some blog posts on the subject would be a great tool to sit alongside the talk. The goal of this comparison is to give C# developers some easy ways to get into Kotlin without having to dive in and build something real. Start with the building blocks you know and draw comparisons to one of the coolest languages on the market.

If you prefer to just jump right into a language / platform – I would happily suggest my Pluralsight course – Building Android Apps with Kotlin: Getting Started. Take a look here: https://app.pluralsight.com/library/courses/building-android-apps-kotlin-getting-started/

C# Async Await

C# has done arguably the best job at simplifying asynchronous programming for developers. We now hardly have to think about thread management, opening, closing, splitting, etc. We can just toss around some async, await, and Task and we’re basically good to go. As long as you’re using it properly all the way through your application, async asyncing all the way through, then you should easily be able to avoid lost threads, race conditions, etc.

If you’re new to async await in C#, here is a quick example of a process that sets a list of dogs entirely in the background (although done unsafely, it’s just a quick dummy sample).

public class DogAdoptionService
{
    List<AdoptableDog> dogs;

    public async Task<List<AdoptableDog>> GetAdoptableDogsAsync()
    {
        var dogJson = await new HttpClient().GetStringAsync("http://mydogservice.azurewebsites.net");
        return JsonConvert.DeserializeObject<List<AdoptableDog>>(dogJson);
    }
    public void BackgroundGet()
    {
        Task.Run(async () => dogs = await GetAdoptableDogsAsync());
    }
}

Kotlin Coroutines

Kotlin’s concept of asynchronous programming takes a different approach, but one that is just as easy to follow and use. They call it Coroutines. I know, I know, they missed an opportunity to call it Koroutines, but still…. they’re great!

class DogAdoptionService {
    var dogs: List<AdoptableDog>? = null
    fun getAdoptableDogs(): List<AdoptableDog> {
        var json = URL("http://mydogservice.azurewebsites.net").readText()
        val listType = object : TypeToken<List<AdoptableDog>>() { }.type
        return Gson().fromJson(json, listType)
    }

    fun getAdoptableDogsInBackground() {
        GlobalScope.launch {
            dogs = getAdoptableDogs()
        }
    }
}

Side note: this really isn’t the best way to make an HTTP GET request in Kotlin, but I wanted to make it as symmetrical as possible between my C# example.

In this example, we launch a new coroutine from the GlobalScope that executes the long running getAdoptableDogs() function. One thing coroutines does that is different from other simple async await style programming is making it easier to create and manage different scopes of your coroutines if you wish. Of course, you can still launch many different coroutines from GlobalScope as well as manage heavy concurrencies.

The docs on Kotlin Coroutines actually has some awesome and simplified examples so I definitely recommend checking that out.
https://kotlinlang.org/docs/reference/coroutines-overview.html

If you wanted to essentially await a coroutine from within another or from within the main thread, all you have to do is get a reference to the coroutine and call .join() on it.

Here’s how that would look in our previous example:

class DogAdoptionService {
    var dogs: List<AdoptableDog>? = null
    fun getAdoptableDogs(): List<AdoptableDog> {
        var json = URL("http://mydogservice.azurewebsites.net").readText()
        val listType = object : TypeToken<List<AdoptableDog>>() { }.type
        return Gson().fromJson(json, listType)
    }

    fun getAdoptableDogsInBackground() {
        val dogsJob = GlobalScope.launch {
            dogs = getAdoptableDogs()
        }

        dogsJob.join() // now we wait for the coroutine to finish before continuing
        system.out.println(dogs)
    }
}

I won’t bore you with tons and tons of samples of coroutines in different situations since the docs (linked above) already do an incredible job of painting different scenarios.

Conclusion

As we continue looking into Kotlin from the perspective of a C# developer, we see more parallels and similarities – especially in both of their ease of asynchronous programming! Whether it’s async await or coroutines, us as application developers can take our minds off of heavy duty thread management and more on our design patterns and implementations!

Let me know what you think in the comments or on twitter and be sure to check back for more developer updates and Kotlin and C# posts!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

New Pluralsight Android Skill IQ Tests

I recently worked with Pluralsight (pluralsight.com) to help produce 2 brand spankin’ new Skill IQ Tests! Test your skills and knowledge of Android development, Android Studio, Kotlin and more!

Android Tooling Skill Assessment

The first is Android Tooling! You can test your knowledge of:

  • Android Studio – Analyze
  • Android Studio – Basics
  • Android Studio – Build
  • Android Studio – Code Manipulation
  • Android Studio – File Structure
  • Android Studio – Run
  • Android Studio – Settings
  • Android Studio – Tools
  • Android Studio – Version Control
  • Gradle

Although this exam is still in Beta (as of writing this post), you can still take the exam and I encourage you to as well! Pluralsight does some really cool work to calibrate the curve of the skill assessment so give it a go and let me know how you do 🙂

Take it here: https://app.pluralsight.com/score/skill-assessment/android-tooling/intro#/v2/landing 


Kotlin: Enhancing App Experience

The second skill assessment is for you Kotlin lovers like me and dives into some deeper knowledge of building better Android apps with Kotlin!

Kotlin is an open-source JVM language created by JetBrains. It is one of the most popular languages used in Android development.

The assessment may cover:

  • Activities
  • Enhanced System Integration
  • Threading and Background Work
  • User Interface and Experience

This assessment is also still in Beta, but be sure to try this one out and see if your Kotlin skills are up to snuff.

Check Out My Course!

Oh wow how topical and convenient! Be sure to check out my course on Building Android Apps with Kotlin: Getting Started to learn a lot about the fundamentals of both the Kotlin language and Android development as a whole! I assure it will help drive that Skill IQ Up for both of these assessments 🙂 

https://app.pluralsight.com/library/courses/building-android-apps-kotlin-getting-started 

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Android Kotlin Basics – Lazy Loading Images with Picasso

About This Series

This “Android Kotlin Basics” blog series is all about fundamentals. We’ll take a look at the basics of building Android apps with Kotlin from the SUPER basics, to the standard basics, to the not-so-basics. We’ll also be drawing comparisons to how things are done in Kotlin vs. Java and some other programming languages to build Android apps (like C# and Xamarin or JavaScript/TypeScript for Hybrid implementations).

Find other posts in this series: Android Kotlin Basics

Check Out the Pluralsight Course!

If you like this series, be sure to check out my course on Pluralsight – Building Android Apps with Kotlin: Getting Started where you can learn more while building your own real-world application in Kotlin along the way. You can also join the conversation and test your knowledge throughout the course with learning checks through each module!

Watch it here: https://app.pluralsight.com/library/courses/building-android-apps-kotlin-getting-started/table-of-contents

Lazy Loading Images with Picasso

Loading images from remote sources without help can be a pain in Android development. You need to make the http request against the url, download the bytes of the image, create a Bitmap from those bytes, then render that BitMap in an ImageView. Not only is that tedious, but it also leaves room for tons of errors and especially the dreaded OutOfMemoryException that happens oh so often when trying to render large images in Android.

There are some really great libraries out there for helping face this issue that can also provide some other useful tools such as filtering, extensions, customizing, and more.

In the course we use Picasso which is a library by Square to help lazy load images. Find it here: http://square.github.io/picasso/

Picasso does a great job loading images asynchronously and handles rendering them with proper scale. It does a great job handling this performance in ListViews and RecyclerViews as well. This is exactly how we use it in our real-world app that we build in the course!

Picasso also has some great features with creating custom transformations or extending the functionality. In this post we will stick to the basics though. If you want to get into details check out the Java documentation at their website. Copy and pasting that into a Kotlin file in Android studio will also automatically translate it for you!

Installing

Picasso can be installed 3 ways:
– Gradle (what we use in the course)
– Maven
– Manual

To install with gradle, add:

implementation 'com.squareup.picasso:picasso:2.71828'

to your build.gradle config.

For maven use:

<dependency>
  <groupId>com.squareup.picasso</groupId>
  <artifactId>picasso</artifactId>
  <version>2.71828</version>
</dependency>

And if you want to do it manually, download the jar from http://square.github.io/picasso/ and reference it in your project.

Basic Image Loading

Now that you have Picasso in your project, lets look at how we can do simple image loading.

Let’s start with a simple layout:

activity_main.xml

<RelativeLayout 
    android:layout_height="match_parent"
    android:layout_width="match_parent">
    <ImageView android:id="@+id/myImageView"
        android:layout_height="match_parent"
        android:layout_width="match_parent" />
</RelativeLayout>

Now in our Activity code, we can load the image from the url in the onCreate override.

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // load the image with Picasso
        Picasso
            .with(this) // give it the context
            .load("https://i.imgur.com/H981AN7.jpg") // load the image
            .into(myImageView) // select the ImageView to load it into
    }
}

If you’re unsure of why we didn’t need to call

val myImageView = findViewByid<ImageView>(R.id.myImageView)

Check out my post on how Kotlin automatically maps views to properties by id: Android Kotlin Basics – Auto-mapping Views

And that’s it! Now you have automatically handled all performance concerns, caching needs, sizing and downloading, and so much more!

Using in a RecyclerView

So loading a single image into a single ImageView isn’t so bad on its own, but when you have to load high-res images into large lists that can change all the time, there are a lot of places this can go wrong doing it yourself. Developers often run into:
– Lag on new items appearing
– Mismatched images
– No images loading
– Images loading incorrectly
– Dreaded Out of Memory Exceptions

Because Picasso runs the image loading asynchronously and only touches the UI thread when it needs to render the image itself, it avoid the issues of locking the UI up when loading. Because it also caches the images locally, when the image needs to be loaded again (such as scrolling back up), it does so quickly and can void mismatching renderings. Also, because it renders the image in chunks before showing it, they avoid the easy to find Out of Memory Exception that we have all come to hate when trying to render a large image into an ImageView. Normally to avoid this, you have to manually load a scaled down image into memory and handle how you scale it per image. Picasso does all this for us too.

On top of all that, Picasso ships with some of the nice-to-haves such as:
– Transitions when images load or change
– Placeholder images to show while loading from a url
– Transformations on images once loaded
– Debugging indicators to show where the image loaded from

All these great features even scale to these large lists and RecyclerViews.

Before showing how to use it in your RecyclerView, be sure to check out the other post in this series: Android Kotlin Basics – RecyclerView and Adapters unless you’re already familiar with how RecyclerViews and Adapters work 🙂

We can create a layout for our item in our list:

image_item.xml

<ImageView android:id="@+id/myImageView"
    android:layout_height="match_parent"
    android:layout_width="match_parent" />

Then a ViewHolder for this image:

ImageHolder.kt

class ImageHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    private val myImageView: ImageView = itemView.findViewById<ImageView>(R.id.myImageView)

    fun updateWithUrl(url: String) {
        Picasso.with(itemView.context).load(url).into(myImageView)
    }
}

Now let’s create our Adapter with our datasource:

ImagesAdapter.kt

class ImageAdapter() : RecyclerView.Adapter<ImageHolder>() {
    val imageUrls: Array<string>

    init {
        imageUrls = arrayOf("https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg", "https://i.imgur.com/kUCMPWX.jpg")
    }

    override fun getItemCount(): Int {
        return imageUrls.size;
    }

    override fun onBindViewHolder(holder: ImageHolder?, position: Int) {
        var imageUrl = imageUrls[position]
        holder?.updateWithUrl(imageUrl)
    }

    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ImageHolder {
        var imageItem = LayoutInflater.from(parent?.context).inflate(R.layout.image_item, parent, false)
        return ImageHolder(imageItem)
    }
}

Last we just need to create our Activity and wireup the Adapter!

activity_main.xml

<RelativeLayout 
    android:layout_height="match_parent"
    android:layout_width="match_parent">    
    <android.support.v7.widget.RecyclerView
        android:id="@+id/imageRecycler"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</RelativeLayout>

MainActivity.kt

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        imageRecycler.layoutManager = LinearLayoutManager(this)
        imageRecycler.adapter = ImageAdapter()
    }
}

Now we can quickly scroll through our list and see the images loaded quickly and properly into our view!

dogs


Also, let me know what else you’d like to learn about with Android and Kotlin! Either drop a comment here or tweet at me @Suave_Pirate!

If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.