[gradle] How/when to generate Gradle wrapper files?

I am trying to understand how the Gradle Wrapper works. In many source repos, I see the following structure:

projectRoot/
    src/
    build.gradle
    gradle.properties
    settings.gradle
    gradlew
    gradlew.bat
    gradle/
        wrapper/
            gradle-wrapper.jar
            gradle-wrapper.properties

My questions:

1. How/when does one generate gradlew/gradlew.bat? Are you supposed to generate them only one time when the project is first created, do you generate them every time you commit/push changes? And how are they generated?
2. Same question above, but for the gradle/wrapper/* files (gradle-wrapper.jar and gradle-wrapper.properties)?
3. Some times I see other *.gradle files inside the project's gradle directory. What are these additional Gradle files and what do they represent/do? Custom plugins?
4. What is the difference in properties that go into settings.gradle vs what should be defined inside gradle.properties?

1. You will generate them once, but update them if you need a new feature or something from a plugin which in turn needs a newer gradle version.

   Easiest way to update: as of Gradle 2.2 you can just download and extract the complete or binary Gradle distribution, and run:

   $ <pathToExpandedZip>/bin/gradle wrapper
   

   No need to define a task, though you probably need some kind of build.gradle file.

   This will update or create the gradlew and gradlew.bat wrapper as well as gradle/wrapper/gradle-wrapper.properties and the gradle-wrapper.jar to provide the current version of gradle, wrapped.

2. Those are all part of the wrapper.

3. Some build.gradle files reference other files or files in subdirectories which are sub projects or modules. It gets a bit complicated, but if you have one project you basically need the one file.

4. settings.gradle handles project, module and other kinds of names and settings, gradle.properties configures resusable variables for your gradle files if you like and you feel they would be clearer that way.

As gradle built-in tasks is deprecated in 4.8, try below

wrapper {
   gradleVersion = '2.0' //version required
}

and run

gradle wrapper

As of Gradle 2.4, you can use gradle wrapper --gradle-version X.X to configure a specific version of the Gradle wrapper, without adding any tasks to your build.gradle file. The next time you use the wrapper, it will download the appropriate Gradle distribution to match.

If you want to download gradle with source and docs, the default distribution url configured in gradle-wrapper.properites will not satisfy your need.It is https://services.gradle.org/distributions/gradle-2.10-bin.zip, not https://services.gradle.org/distributions/gradle-2.10-all.zip.This full url is suggested by IDE such as Android Studio.If you want to download the full gradle,You can configure the wrapper task like this:

task wrapper(type: Wrapper) {
    gradleVersion = '2.13'
    distributionUrl = distributionUrl.replace("bin", "all")
}

Generating the Gradle Wrapper

Project build gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.

// Running 'gradle wrapper' will generate gradlew - Getting gradle wrapper working and using it will save you a lot of pain.
task wrapper(type: Wrapper) {
    gradleVersion = '2.2' 
}

// Look Google doesn't use Maven Central, they use jcenter now.
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.0.1'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

Then at the command-line run

gradle wrapper

If you're missing gradle on your system install it or the above won't work. On a Mac it is best to install via Homebrew.

brew install gradle

After you have successfully run the wrapper task and generated gradlew, don't use your system gradle. It will save you a lot of headaches.

./gradlew assemble

What about the gradle plugin seen above?

com.android.tools.build:gradle:1.0.1

You should set the version to be the latest and you can check the tools page and edit the version accordingly.

See what Android Studio generates

The addition of gradle and the newest Android Studio have changed project layout dramatically. If you have an older project I highly recommend creating a clean one with the latest Android Studio and see what Google considers the standard project.

Android Studio has facilities for importing older projects which can also help.

This is the command to use to tell Gradle to upgrade the wrapper such that it will grab the distribution versions of libraries that includes source code:

./gradlew wrapper --gradle-version <version> --distribution-type all

Specifying the distribution-type with "all" will make sure Gradle downloads source files for use by your development environment.

Pros:

• IDEs will have immediate access to source code. For example, Intellij IDEA won't prompt you to update your build scripts to include the source distro (because this command already did that)

Cons:

• Longer/Bigger build process because it's downloading source code. This is a waste of time/space on a build or CI server where the source code is not necessary.

Please comment or provide another answer if you know of any command line option to tell Gradle not to download sources on a build server.