Hello World Application in Xamarin

First you must install Xamarin for Android.

 

Let's Start

1. Go to File -> New -> Project.

2.  Select Android Application -> Give it a Name.

 

Before starting, have a look at Solution Explorer. An Android Application contains Properties, References, Assets and Resources and so on. Properties contain AssemblyInfo (the same as you saw in the C# project). The References folder contains Assembly Files (DLL files). The Mono.Android DLL assembly contains the C# binding to the Android API.

 

The resources folder contains a Drawable folder (that contains icons and images for the application), Layout (provides a designer surface for the application). Resource.Designer.cs contains auto generated code. As we will start from the basics, delete the main.axml layout and the Activity1.cs file from the project.

3. Right-click on Layout then seelct Add -> New Item.

 

4. Add an Android Layout (named Main.axml) then click on Add and select it.

 

 

5. Drop a Button control from the Toolbox. 

 

Set the Button text as "Click Me!" and id as "@+id/btn_Hello".

 

Main.axml code: 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:minWidth="25px"
    android:minHeight="25px">
    <Button
        android:text="Click Me!"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btn_Hello" />
</LinearLayout>

6. Add a new item then select Activity then click on Add.

 

Activity1.cs Code: 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;

namespace Hello_World_Application
{
    //Set the Label = "Hello World Application" which is displayed on the Top of the Application(in Title)
    //Set MainLauncher = true makes this Activity as a Main Activity and Application starts from this Activity.
    //Set Icon using Icon = "@drawable/icon"
    [Activity(Label = "Hello World Application", MainLauncher = true, Icon = "@drawable/icon")]
    public class Activity1 : Activity
    {
        //Creating Instance of Button
        Button btn_Hello;
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            //SetContentView
            SetContentView(Resource.Layout.Main);
            //Get btn_Hello Button control from the Manin.axml Layout.
            btn_Hello = FindViewById<Button>(Resource.Id.btn_Hello);
            //Creating Click event of btn_Hello
            btn_Hello.Click += btn_Hello_Click;
        }
        //btn_Hello Click Event
        void btn_Hello_Click(object sender, EventArgs e)
        {
            //Display a Toast Message on Clicking the btn_Hello
            Toast.MakeText(this, "Hello World Application by Anoop", ToastLength.Short).Show();
        }
    }
}

7. Build and run the application. Start an emulator image if not started. Select the Running devices and then click on OK. 

Note: the Emulator takes a lot of time to start. Enable USB Debugging on your Android Device and run your application on the Device directly; that is much faster compared to debugging on an emulator.

 

Final preview: 

 

I hope you like it. Thanks.