Q:

Best way to incorporate Volley (or other library) into Android Studio project

I've seen different advice on the best way to do this This question covers creating a jar. Elsewhere, I've seen advice to simply copy the volley source into your own project. This section on libraries at android.com would seem the most authoritative. However, after compiling volley, I don't have an aal library, whereas that section says I should have.
So my question is this: I have an existing Android Studio project with a standard layout, and a git repository; what should I do to add volley? Where should I download it to? How should I add it to Android Studio? Which Gradle files, if any, do I need to modify.
Hopefully, for those of you have done this a few times, this should be bread-and-butter stuff, but I haven't been able to find a straightforward description.
--
Updating, per Scott Barta's suggestion.
The gradle.build file in the volley repository has this line.
apply plugin: 'android-library'

According to the documentation: "Library projects do not generate an APK, they generate a .aar package (which stands for Android archive)." However, when I build the volley project, no .aar is created.
My feeling is that as Volley is a library project, created by the Android team, it is most probably intended to be generated and used as .aar package. Any advice on whether it would be preferable to generate a .aar, and how to do that, would be appreciated.

A:

As pointed out by others as well, Volley is officially available on Github:
Add this line to your gradle dependencies for volley:
compile 'com.android.volley:volley:1.0.0' 

To install volley from source read below:
I like to keep the official volley repository in my app. That way I get it from the official source and can get updates without depending on anyone else and mitigating concerns expressed by other people.
Added volley as a submodule alongside app.
git submodule add -b master https://github.com/google/volley.git volley

In my settings.gradle, added the following line to add volley as a module.
include ':volley'

In my app/build.gradle, I added a compile dependency for the volley project
compile project(':volley')

That's all! Volley can now be used in my project.
Everytime I want to sync the volley module with Google's repo, i run this.
git submodule foreach git pull

A:

LATEST UPDATE:
Use the official version from jCenter instead.
dependencies {
    compile 'com.android.volley:volley:1.0.0'
}

The dependencies below points to deprecated volley that is no longer maintained.
ORIGINAL ANSWER
You can use this in dependency section of your build.gradle file to use volley
  dependencies {
      compile 'com.mcxiaoke.volley:library-aar:1.0.0'
  }

UPDATED:
Its not official but a mirror copy of official Volley. It is regularly synced and updated with official Volley Repository so you can go ahead to use it without any worry.
https://github.com/mcxiaoke/android-volley

A:

Nowadays
dependencies {
    compile 'com.android.volley:volley:1.0.0'
}   

A lot of different ways to do it back in the day (original answer)

Add volley.jar as library

Download it from: http://api.androidhive.info/volley/volley.jar
Place it in your [MyProjectPath]/app/libs/ folder

Use the source files from git (a rather manual/general way described here)

Download / install the git client (if you don't have it on your system yet): http://git-scm.com/downloads
(or via git clone https://github.com/git/git ... sry bad one, but couldn't resist ^^)
Execute git clone https://android.googlesource.com/platform/frameworks/volley
Copy the com folder from within [path_where_you_typed_git_clone]/volley/src to your projects app/src/main/java folder (Integrate it instead, if you already have a com folder there!! ;-))

The files show up immediately in Android Studio. For Eclipse you will have to right-click on the src folder and press refresh (or F5) first.

Use gradle via the "unofficial" maven mirror

In your project's src/build.gradle file add following volley dependency:
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    // ...

    compile 'com.mcxiaoke.volley:library:1.+'
}

Click on Try Again which should right away appear on the top of the file, or just Build it if not

The main "advantage" here is, that this will keep the version up to date for you, whereas in the other two cases you would have to manually update volley. 
On the "downside" it is not officially from google, but a third party weekly mirror.
But both of these points, are really relative to what you would need/want. 
Also if you don't want updates, just put the desired version there instead e.g. compile 'com.mcxiaoke.volley:library:1.0.7'.

