Building a Reactive Functional Todo Application with Kotlin in Android (Part 2)

What Will I Learn?

• You will learn how to use Constraint Layouts and List Views in Android
• You will learn how to work with Observables and Subscribers with Kotlin in Android
• You will learn how to use filters and higher order functions in an Android activity

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 tutorial, we finish off our Reactive Functional Android Todo Application by building out the User Interface (UI) and the main activity. We first start by looking at the various options that we have for building out our User Interface. We use Android Constraint Layouts to position the elements inside of our layouts. We also talk about how we can manually set the dimensions and properties of each element by way of the Graphical User Interface Editor in Android Studio. We use a List View to bind our Todo items in a fairly quick and streamlined way. Also, this project makes use of the Button, Edit View, Floating Action Button, Check Box and Text View fields. We use the FAB specifically to implement a small menu in this application.

We then set about implementing the main activity of our project. We interface this activity with our store and data layer by having it subscribe to the Observable stream. The Renderer Interface that was built in the last tutorial is also used to bind the data onto the List View through a Custom List View Adapter that also extends the Array Adapter class. We create a Higher Order Function to manipulate and filter the Observable Data. In this way, we are able to make it so that our FAB has the ability to filter our data into subsets based on the status of the data. Finally, we add various on click listeners and on long press listeners to allow the user of the application to add, remove and update the Todo Items in our application.

The source code for this project can be found here

Video Tutorial

Curriculum

• Building a Reactive Functional Todo Application with Kotlin in Android (Part 1)

Related Content

• Android Applications in Kotlin

• Building a Web View with Kotlin and Android

• 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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