Introduction

Android is an open-source operating system for mobile devices. There are more than 2.5 billion active Android devices in the world. The articles in this series will help you create amazing apps for these devices.

Android Architecture

Android is a layered environment, built upon a foundation of the Linux kernel.

The main components of the android architecture are:

The programming languages widely used for building native android apps are Kotlin and Java. We’ll be using Kotlin in this article, so you might wanna learn the basics of the language before continuing.

Here are some fundamentals to understand when starting out with Android development.

AndroidManifest.xml

Every app project must have an AndroidManifest.xml file at the root of the project. The manifest file describes essential information about your app to the Android build tools and the Android operating system.

The /res folder

The res folder is where most application resources are stored. The main content categories include drawable, layouts, and values.

App Components

With that, let’s get into the fun stuff. The easiest way to get started with developing Android applications is with Android Studio (Don’t blame me if your laptop is on fire xD)

Building a basic application

To create the application, we will follow the new application wizard to step us through the process in a pretty painless manner.

We’ll be building a simple application that changes the background color when a button is clicked.

Android Studio creates an application with a single activity that contains a text element. We’ll modify this layout to have 2 buttons

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/parent_layout"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/toggle_red"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="red"/>
    <Button
        android:id="@+id/toggle_blue"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="blue"/>

</LinearLayout>

Now the UI looks like this :

Now that the buttons are done, it’s time to add some functionality.

package com.example.myapplication

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.LinearLayout

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

        var toggleRed: Button = findViewById(R.id.toggle_red)
        var toggleBlue: Button = findViewById(R.id.toggle_blue)
        var parentLayout: LinearLayout = findViewById(R.id.parent_layout)

        toggleRed.setOnClickListener {
            parentLayout.setBackgroundColor(resources.getColor(R.color.red))
        }
        toggleBlue.setOnClickListener {
            parentLayout.setBackgroundColor(resources.getColor(R.color.blue))
        }

    }
}

Let’s break down this code,

Now let’s build and run the app.

Of course, this is not the most amazing app you’ve seen, but it’s a good app to get started with app development. Try building an app and DM it to us on Instagram. Interesting entries will be featured on our page, so be as creative as you can! Happy coding !!

An Introduction to Android App Development