In this chapter, we'll explore how to create a small yet powerful Android application using Xamarin, a popular framework for building cross-platform apps. With swift app development, you can quickly bring your ideas to life and deploy them across multiple platforms.

To get started, fire up Visual Studio and navigate to File → New → Project. On the menu dialog box that appears, head to Templates → Visual C# → Android → Blank App (Android). Give your application a fitting name, such as "helloWorld," and save it in the default location provided. Next, click OK to load the new helloXamarin project.

Next, open the Resources → layout → Main.axml file and switch from Design View to Source view. Add the following lines of code to build your app:

`xml

android:orientation="vertical"

android:background="#d3d3d3"

android:layout_width="fill_parent"

android:layout_height="fill_parent">

android:text="@string/HelloXamarin"

android:textAppearance="?android:attr/textAppearanceLarge"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:id="@+id/textView2"

android:textColor="@android:color/black" />

`

In this code, we've created a new Android textview. To store information and values about the button, open the folder values and double-click Strings.xml to open it.

`xml

Hello World, I am Xamarin!

helloWorld

`

Open the MainActivity.cs file and replace the existing code with the following lines:

`csharp

using System;

using Android.App;

using Android.Content;

using Android.Runtime;

using Android.Views;

using Android.Widget;

using Android.OS;

namespace HelloXamarin

{

public class MainActivity : Activity

{

protected override void OnCreate(Bundle bundle)

{

base.OnCreate(bundle);

SetContentView(Resource.Layout.Main);

}

}

}

`

Save the application, build it, and then run it to display the created app in an Android Emulator.

To set up an Android emulator, navigate to Tools → Android → Android Emulator Manager. On the pop-up window that appears, click Create button. Fill in the rest of the fields and click OK to launch the emulator.

Now that you have your emulator ready, let's modify our project by creating a button that displays text upon click. Open Main.axml and switch to source view. Add the following code:

`xml

android:id="@+id/MyButton"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/ButtonClick" />

`

After adding a button, our full code will look like this:

`xml

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent">

android:text="@string/HelloXamarin"

android:textAppearance="?android:attr/textAppearanceLarge"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:id="@+id/textView2" />

android:id="@+id/MyButton"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/ButtonClick" />

`

Next, register our button values in the strings.xml file:

`xml

Click Me!

`

After adding our button in the strings.xml file, we'll open MainActivity.cs file to add an action for our button when it's clicked, as shown in the following code:

`csharp

using System;

using Android.App;

using Android.Content;

using Android.Runtime;

using Android.Views;

using Android.Widget;

using Android.OS;

namespace HelloXamarin

{

[Activity(Label = "HelloXamarin", MainLauncher = true, Icon = "@drawable/icon")]

public class MainActivity : Activity

{

protected override void OnCreate(Bundle bundle)

{

base.OnCreate(bundle);

SetContentView(Resource.Layout.Main);

Button button = FindViewById