Delve into building Android apps using Kotlin. Gain hands-on experience with tools like Groovy and XML while creating a Travel Blog app for your portfolio.

This course is for anyone looking to build their own Android applications. Ever since Google announced that Kotlin is the language of choice for Android development, Kotlin has become increasingly popular.

In this course, you’ll take a hands-on, project-based approach to developing Android applications. You’ll work with the most common tools that Android developers use every day, including Kotlin, Groovy, and XML. As you learn, you’ll build a fully functional Travel Blog Application that will be a great addition to your portfolio.

By the end of this course, you’ll have tangible experience building an Android application and be ready to build even more complex projects.

John

Great practical approach to learn Android Development

Engineer

Modern Android App Development with Kotlin

# Flow overview

When a user clicks the *_login_* button we will perform a data validation flow, and if the data is valid, proceed to:

1. Simulate long-running operation for 2 seconds
2. Open *_MainActivity_* 
3. Finish *_LoginActivity_*

# Simulate a long-running operation

In this lesson, we are not going to do a real login HTTP call, so let’s just simulate it via delay of 2 seconds before opening *_MainActivity_*. In a real application, we would need to create an HTTP client to send login data and retrieve a response from the backend REST service. 

To perform a delay we can use the `Handler` object.

In Android, the `Handler` is an object which is tied to the [looper](https://developer.android.com/reference/android/os/Looper) of the thread in which it’s been created. It typically has two use-cases:

1. If we want to execute code on the *_main_* thread
2. If we want to execute code with a delay or at the specific time

Let’s modify our `performLogin` method and create a `Handler` object at the very end.  Now we can use this object's `postDelayed` method to execute code with a delay. This method has two parameters:

- The `Runnable` that will be executed *_(presented as lambda in the code below)_*
- The delay (in milliseconds) until the `Runnable` will be executed

Learn and practice how to simulate a long-running operation and open a new screen in this lesson.


Android Ecosystem

Hello World

Travel Blog - Login Screen

Travel Blog - Details Screen

Travel Blog - List Screen

Travel Blog - Search & Sort

Travel Blog - Offline

Conclusion

Launch Second Screen

Flow overview

Simulate a long-running operation