KOTLIN ANDROID APP DEVELOPMENT COURSE, CREATING THE FIRST APP

Hello! In this post, I will explain the first steps in developing an Android application using Kotlin. Android is a mobile operating system developed by Google that runs many applications worldwide. In this post, we will create a simple “Hello World” application to learn the basics of Android application development.

1. Setting Up the Development Environment

To develop Android applications, several tools are required. In this section, we will learn how to set up the development environment.

1.1. Installing Android Studio

Android Studio is the official IDE for Android app development. Follow the steps below to install it.

1. Download the installation file from the official Android Studio website here.
2. Run the downloaded file and follow the installation wizard. The necessary SDK and emulator will also be installed.
3. Once the installation is complete, launch Android Studio.

1.2. Installing JDK

Kotlin is a language based on the JVM, so you need the JDK (Java Development Kit). Typically, installing Android Studio will also install the JDK, but you can install it manually if necessary. Download and install the JDK from Oracle’s official website.

2. Creating Your First App

Now that everything is set up, let’s create our first Android application. We will create the simplest app, the “Hello World” app.

2.1. Creating a Project

1. After launching Android Studio, select “New Project”.
2. Select “Empty Activity” and click “Next”.
3. Enter “HelloWorld” for the Project Name and set the Package Name to “com.example.helloworld”.
4. Set the Save location to your desired location, select “Kotlin” for the Language, and then click “Finish”.

2.2. Creating the App Layout

Once the project is created, we will modify the default layout file provided. Open the res/layout/activity_main.xml file and enter the following code.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/hello_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello, World!"
        android:layout_centerInParent="true"
        android:textSize="24sp"
        android:textColor="#000000"/>

    </RelativeLayout>

2.3. Modifying the Activity

Now let’s modify the main activity file to add the app’s execution logic. Open the MainActivity.kt file and enter the following code.

package com.example.helloworld

    import androidx.appcompat.app.AppCompatActivity
    import android.os.Bundle

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

3. Running the App

Now let’s run the “Hello World” app. Follow these steps in Android Studio.

1. Select the emulator you want to use from the drop-down menu at the top, or create a new one.
2. Click the run button (green arrow) at the top.
3. Once the emulator starts, you will see the text “Hello, World!”.

4. Conclusion

We have now created a simple “Hello World” app. Throughout this process, we learned the basics of using Android Studio, the layout file, and how to modify the activity. To create more complex apps in the future, we need to learn about various elements such as layouts, views, user input handling, and data management.

Next time, we will work on an app with more advanced features. Until then, please practice to fully understand the basic concepts! If you have any questions, feel free to ask in the comments.