build.gradle

/**
 * The buildscript block is where you configure the repositories and
 * dependencies for Gradle itself—meaning, you should not include dependencies
 * for your modules here. For example, this block includes the Android plugin for
 * Gradle as a dependency because it provides the additional instructions Gradle
 * needs to build Android app modules.
 */

buildscript {

    /**
     * The repositories block configures the repositories Gradle uses to
     * search or download the dependencies. Gradle pre-configures support for remote
     * repositories such as JCenter, Maven Central, and Ivy. You can also use local
     * repositories or define your own remote repositories. The code below defines
     * JCenter as the repository Gradle should use to look for its dependencies.
     *
     * New projects created using Android Studio 3.0 and higher also include
     * Google's Maven repository.
     */

    repositories {
        mavenCentral()
        google()
        jcenter()
    }

    /**
     * The dependencies block configures the dependencies Gradle needs to use
     * to build your project. The following line adds Android plugin for Gradle
     * version 3.0.1 as a classpath dependency.
     */

    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.3'
    }
}

/**
 * The allprojects block is where you configure the repositories and
 * dependencies used by all modules in your project, such as third-party plugins
 * or libraries. However, you should configure module-specific dependencies in
 * each module-level build.gradle file. For new projects, Android Studio
 * includes JCenter and Google's Maven repository by default, but it does not
 * configure any dependencies (unless you select a template that requires some).
 */

allprojects {
    repositories {
        google()
        jcenter()
    }
}