Developing the Messenger app

First, we need to create a new Android Studio project for the application. Create a new Android Studio project with the name Messenger and the package name com.example.messenger. Feel free to take a look at Chapter 1, The Fundamentals, to refresh your memory on Android project creation. In the process of project setup, when asked to create a new launcher activity, name the activity LoginActivity and make it an empty activity.

Including project dependencies

Over the course of this chapter, we will make use of a number of external application dependencies. As such, it is important we include them in the project now. Open your module-level build.gradle file and add the following dependencies to it:

dependencies {
  implementation fileTree(dir: 'libs', include: ['*.jar'])
  implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7
                  :$kotlin_version"
implementation 'com.android.support:appcompat-v7:26.1.0'
implementation 'com.android.support.constraint...