Building a Crypto Tracker with Kotlin in Android (Part 2)

What Will I Learn?

• You will learn how to implement and use Dagger 2 in Android with Kotlin
• You will learn how to use Android Shared Preferences to build a key-value data store
• You will learn how to use OkHttp3 and Retrofit with Kotlin

Requirements

• Android Studio 3.0 or Android Studio Canary
• A basic understanding of the Android ecosystem
• A fair understanding of Kotlin or the Java programming language

Difficulty

• Intermediate

Description

In this second video tutorial, we continue to build out our Cryptocurrency Tracker Application with Kotlin in Android. First, we start by creating a small Key-Value store using the Android Shared Preferences class library. This is a fairly light document storage option that exists as a native library in the Android ecosystem. It allows us to store our Cryptocurrency data in small documents on the user's device.

We build out an abstract class to use as a skeleton mold for the rest of our activities in this application. Using abstract classes in this way has various advantages and it allows us to save code and avoid boilerplate by letting us implement super methods in one place. We also create abstract functions to initialize the injection of data, the setup of our layouts and the inflation of our views.

We create a few dagger dependency injection modules and a dagger component which implements these modules. These modules allow us to define a bunch of singleton objects that let us serve consistent state across all of the activities in our application. We make use of the OkHttp3 client to handle Http Requests and Responses, create a cache as well as build out a connection pool. We then also add on the Retrofit client to call a GET method on the coinmarketcap API and serve the response data as GSON objects to our parcelable data model.

The resulting providers are then added to our component which implements a function that allows us to inject them into our main activity. Dagger 2 generates code that gives the injected classes access to these providers and their state. The Dependency Injection Pattern will allow us to easily implement the other activities in our Application and give them these features.

The source code for this project can be found here

Video Tutorial

Curriculum

• Building a Crypto Tracker with Kotlin in Android (Part 1)

Related Content

• Android Applications in Kotlin

• Building a Web View with Kotlin and Android
• Building a Reactive Functional Todo Application with Kotlin in Android (Part 1)
• Building a Reactive Functional Todo Application with Kotlin in Android (Part 2)

• Desktop Applications in Kotlin

• Building a Calculator with Kotlin (TornadoFX, FXML, Desktop Application)
• Building an API with Kotlin and Ktor

• Intro to Kotlin Series

• Intro to Kotlin (Basic Types, Type Inference, Casting and Strings)
• Intro to Kotlin (Basic Operations and Collections)
• Intro to Kotlin (Control Flow and Conditionals)
• Intro to Kotlin (Functions in Kotlin)
• Intro to Kotlin (Advanced Functions)
• Intro to Kotlin (Classes, Visibility Modifiers, Objects)
• Intro to Kotlin (Nullables, Data Classes, Enum Classes and Sealed Classes)
• Intro to Kotlin (Interfaces, Inheritance, Type Alias and Abstract Classes)

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Posted on Utopian.io - Rewarding Open Source Contributors

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