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Kotlin Programming By Example
Kotlin Programming By Example

Kotlin Programming By Example: Build real-world Android and web applications the Kotlin way

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Kotlin Programming By Example

Building an Android Application – Tetris

In the previous chapter, we took a concise look at crucial topics pertaining to the core Kotlin language. These topics took us through the fundamentals of Kotlin as well as the powerful object-oriented programming approach to software development it puts at our disposal. In this chapter, we will put the knowledge we gained from the previous chapter to good use by developing an Android application.

In this chapter, you will learn about the following topics:

  • Android application components
  • Views
  • View groups
  • Layout constraints
  • Implementing layouts with XML
  • String and dimension resources
  • Handling input events

We will learn these topics through a hands-on approach by implementing the layouts and components of a classic game, Tetris, in the form of an Android application. As we are developing the game in the form of an Android application...

Android – an overview

Android is a Linux-based mobile operating system developed and maintained by Google and created primarily to power smart mobile devices such as mobile phones and tablets. The primary interface to interact with the Android operating system is Graphic User Interface (GUI)-based. Users of devices powered by Android manipulate and interact with the operating system environment primarily via a visual touch-based interface by performing gestures such as taps and swipes on the display.

Software can be installed on the Android OS in the form of apps. An app is an application that runs within an environment and performs one or more tasks for the achievement of a goal or a collection of goals. The ability to install applications on mobile devices presented a huge opportunity to both users and application developers. Users take advantage of the features provided...

Understanding Tetris

Before attempting to develop the Tetris game as an Android application, we need to understand the game, its rules, and its constraints.

Tetris is a matching puzzle video game that makes use of tiles. The name Tetris is derived from the words tetra – the Greek numerical prefix for four – and tennis. The tiles in Tetris combine to make up tetrominoes which are geometric shapes composed of four squares connected orthogonally:

Tetris tetrominoes

In Tetris, a random sequence of tetrominoes fall down upon a playing field. These tetrominoes can be manipulated by the player. A number of motions can be performed on each tetromino piece. Pieces can be moved to the left, to the right, and rotated. In addition, the speed of descent of each piece can be sped up. The objective of the game is to create an uninterrupted horizontal line of ten cells with the...

Creating the user interface

As previously mentioned, the user interface is the means by which the user of an application interacts with the app. It cannot be overstated how important the user interface of an application is. Before embarking on the process of actually coding a user interface, it may be helpful to make a graphical representation of the UI to be implemented. This can be done with different tools, such as Photoshop, but for this case, a simple sketch is sufficient:

From the preceding sketch, we can see that we will need two distinct screens in this application: the landing screen and the game screen where the actual gameplay will happen. These two screens will require two separate activities. We'll call these two activities MainActivity and GameActivity.

MainActivity will serve as the entry point of our application. It will contain the user interface and all...

The app manifest

The app manifest is an XML file that is present in every Android application. It is located in the manifests of an application's root folder. The manifest file holds crucial information pertaining to an application on the Android operating system. The information contained in an application's androidManifest.xml must be read by the Android system before an application can be run. Some of the information that must be registered in the app manifest are:

  • The Java package name for the application
  • The activities present in the application
  • Services that are used in the application
  • Intent filters that direct implicit intents to an activity
  • Descriptions of the broadcast receivers used in the application
  • Data pertaining to content providers present in the application
  • The classes that implement the various application components
  • The permissions that are required...

Summary

In this chapter, we took a closer look at the Android application framework. In the process, we learned about several things, such as the seven fundamental Android app components: activities, intents, intent filters, fragments, services, loaders, and content providers.

In addition, we took a close look at the process of creating a layout, the constraint layout, types of layout constraints that exist, string, dimension resources, views, view groups, and working with SharedPreferences. In the next chapter, we will delve further into the world of Tetris and implement the gameplay as well as critical application logic.

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Key benefits

  • Build three full-fledged, engaging applications from scratch and learn to deploy them
  • Enhance your app development and programming activities with Kotlin’s powerful and intuitive tools and utilities.
  • Experience the gentle learning curve, expressiveness, and intuitiveness of Kotlin, as you develop your own applications

Description

Kotlin greatly reduces the verbosity of source code. With Google having announced their support for Kotlin as a first-class language for writing Android apps, now's the time learn how to create apps from scratch with Kotlin Kotlin Programming By Example takes you through the building blocks of Kotlin, such as functions and classes. You’ll explore various features of Kotlin by building three applications of varying complexity. For a quick start to Android development, we look at building a classic game, Tetris, and elaborate on object-oriented programming in Kotlin. Our next application will be a messenger app, a level up in terms of complexity. Before moving onto the third app, we take a look at data persistent methods, helping us learn about the storage and retrieval of useful applications. Our final app is a place reviewer: a web application that will make use of the Google Maps API and Place Picker. By the end of this book, you will have gained experience of of creating and deploying Android applications using Kotlin.

Who is this book for?

This book is for those who are new to Kotlin or are familiar with the basics, having dabbled with Java until now. Basic programming knowledge is mandatory.

What you will learn

  • Learn the building blocks of the Kotlin programming language
  • Develop powerful RESTful microservices for Android applications
  • Create reactive Android applications efficiently
  • Implement an MVC architecture pattern and dependency management using Kotlin
  • Centralize, transform, and stash data with Logstash
  • Secure applications using Spring Security
  • Deploy Kotlin microservices to AWS and Android applications to the Play Store
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Publication date, Length, Edition, Language, ISBN-13
Publication date : Mar 28, 2018
Length: 500 pages
Edition : 1st
Language : English
ISBN-13 : 9781788474542
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Product Details

Publication date : Mar 28, 2018
Length: 500 pages
Edition : 1st
Language : English
ISBN-13 : 9781788474542
Category :
Languages :
Tools :

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Table of Contents

11 Chapters
The Fundamentals Chevron down icon Chevron up icon
Building an Android Application – Tetris Chevron down icon Chevron up icon
Implementing Tetris Logic and Functionality Chevron down icon Chevron up icon
Designing and Implementing the Messenger Backend with Spring Boot 2.0 Chevron down icon Chevron up icon
Building the Messenger Android App – Part I Chevron down icon Chevron up icon
Building the Messenger Android App – Part II Chevron down icon Chevron up icon
Storing Information in a Database Chevron down icon Chevron up icon
Securing and Deploying an Android App Chevron down icon Chevron up icon
Creating the Place Reviewer Backend with Spring Chevron down icon Chevron up icon
Implementing the Place Reviewer Frontend Chevron down icon Chevron up icon
Other Books You May Enjoy Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Half star icon Empty star icon 3.3
(4 Ratings)
5 star 50%
4 star 0%
3 star 0%
2 star 25%
1 star 25%
SURENDRA PATEL Nov 02, 2019
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Good book
Amazon Verified review Amazon
Amie Jun 07, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Packt always has awesome programming books. I come from a strong iOS background and this was easy to pick up and read and learn Kotlin.
Amazon Verified review Amazon
Amazon Customer Aug 03, 2019
Full star icon Full star icon Empty star icon Empty star icon Empty star icon 2
The idea behind this book sounded great, but the execution was lacking. The description promises to 'teach the building blocks of the Kotlin programming language' and is meant for 'those new to Kotlin.' And the first chapter does go over some of the most rudimentary syntax of the language, like how to declare a variable. But that is the last time it really tries to educate the reader about the language. The rest of the book is just a code dump and leaves understanding unexplained syntax and language features an exercise for the reader to figure out. Many times what little explanatory text there is does not agree with the code that is provided. It spends more time explaining how to use Android Studio than it does on how the code actually works.This book may be good for someone that already has a firm grasp on Kotlin and its libraries, and is looking for examples on how to move into app or web development, but it is not for someone that is looking to learn Kotlin, by example or otherwise.
Amazon Verified review Amazon
A Jun 14, 2019
Full star icon Empty star icon Empty star icon Empty star icon Empty star icon 1
Clearly written in a rush and of a poor quality. Due to the amount of mistakes, it is hard to follow. Whilst the attached image doesn't express how the book can be hard follow, it does show how sloppy the proof reading and editing is.
Amazon Verified review Amazon
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