Building Your First Android App: A Beginner's Guide

So, you’ve decided to dive into Android development—great choice! With over 3 billion active Android devices worldwide, building Android apps opens up a massive opportunity for developers. Whether you're looking to create the next big app or just want to expand your programming skills, this guide will walk you through building your first Android app from scratch.

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Prerequisites

Before we begin, ensure you have:

• Basic knowledge of Java or Kotlin (Kotlin is now the preferred language for Android).
• Android Studio installed (download here).
• An Android device or emulator for testing.

Step 1: Setting Up Android Studio

Android Studio is the official IDE for Android development. After installing:

1. Launch Android Studio and select "Start a new Android Studio project".
2. Choose "Empty Activity" and click Next.
3. Configure your project:
   • Name: MyFirstApp
   • Package name: com.example.myfirstapp (follow reverse domain naming)
   • Save location: Choose a directory.
   • Language: Kotlin (recommended)
   • Minimum SDK: API 21 (Android 5.0 - covers ~95% of devices)

Click Finish, and Android Studio will generate your project.

Step 2: Understanding the Project Structure

Your project contains several key folders:

• app/src/main/java/ – Contains Kotlin/Java code.
• app/src/main/res/ – Holds resources like layouts (layout/), strings (values/), and images (drawable/).
• app/manifests/AndroidManifest.xml – Defines app metadata, permissions, and activities.

Step 3: Designing the User Interface

Open activity_main.xml (under res/layout/) to design your app’s UI. By default, it uses a ConstraintLayout.

Let’s modify it to include a TextView and a Button:

xml

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<LinearLayout  
    xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="vertical"  
    android:gravity="center"  
    android:padding="16dp">  

    <TextView  
        android:id="@+id/textView"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="Hello, Android!"  
        android:textSize="24sp" />  

    <Button  
        android:id="@+id/button"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="Click Me" />  
LinearLayout>

Step 4: Adding Functionality with Kotlin

Now, open MainActivity.kt (in java/ folder) to add logic. We’ll make the button update the text when clicked:

kotlin

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

        val textView = findViewById<TextView>(R.id.textView)  
        val button = findViewById<Button>(R.id.button)  

        button.setOnClickListener {  
            textView.text = "Button Clicked!"  
        }  
    }  
}

1. Finds the TextView and Button from the XML.
2. Sets a click listener on the button to change the text.

Step 5: Running Your App

Click the green Run button (▶) in Android Studio. Choose an emulator or connect a real device (enable USB debugging in Developer Options).

If everything works, you’ll see your app with the text and button. Clicking the button changes the text!

Step 6: Improving the App

Adding a Second Activity

Most apps have multiple screens. Let’s add a second activity:

1. Right-click java/ folder → New → Activity → Empty Activity.
2. Name it SecondActivity and click Finish.
3. Open activity_second.xml and add a TextView:

xml

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<TextView  
    android:layout_width="wrap_content"  
    android:layout_height="wrap_content"  
    android:text="Welcome to the Second Screen!"  
    android:textSize="20sp" />

4. Now, modify MainActivity.kt to open SecondActivity when the button is clicked:

kotlin

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button.setOnClickListener {  
    val intent = Intent(this, SecondActivity::class.java)  
    startActivity(intent)  
}

Step 7: Publishing Your App

Once your app is ready, you can publish it to the Google Play Store:

1. Generate a signed APK/Bundle:
   • Go to Build → Generate Signed Bundle / APK.
   • Follow the wizard (you’ll need a keystore for security).
2. Create a Google Play Developer Account (sign up here).
3. Upload your app, set pricing (free/paid), and submit for review.

Final Thoughts

Congratulations! You’ve built your first Android app. The next steps?

• Learn more about Jetpack Compose (modern UI toolkit).
• Explore Firebase for backend services.
• Check out Android’s official docs for deeper learning.

And if you're interested in making money with your web development skills, don’t forget to explore MillionFormula.

Happy coding!