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Can't find v7 Preference Support Library in Eclipse ADT

I'm currently using Eclipse ADT 23.0.7 for android app development. My SDK manager is updated for Android 6.0 shown in below..I want to use v7 Preference Support Library in my project. but, unfortunately I can't found it in my (sdk)/extras/android/support/v7 directory as stated in Android Developer Website. I can't figure out what to do. Thanks in advance for any kind of help!UPDATE 1I've also tried to re-download the library but, nothing happen. Preference library is still missing.

Google stopped to provide Eclipse projects. It pushes developers to migrate from Eclipse to Android Studio. So all libraries are available as *.aar files
But it is still possible to these files in Eclipse.
Find the aar for your library at \android-sdk\extras\android\m2repository\com\android\support\preference-v7\23.0.1\
Then use instructions from CommonsWare guy Consuming AARs from Eclipse:
UnZIP the AAR into some directory.
Create an empty directory that will be the home for the Android
library project. For the rest of these steps, I will refer to this as
“the output directory”.
Copy the AndroidManifest.xml, res/, and assets/ directories from the
AAR into the output directory.
Create a libs/ directory in the output directory. Copy into libs/ the
classes.jar from the root of the unZIPped AAR, plus anything in libs/
in the AAR (e.g., mediarouter-v7 has its own JAR of proprietary bits).
Decide what build SDK you want to try to use. You might just choose
the highest SDK version you have installed. Or, you can use the
android:minSdkVersion and the -vNN resource set qualifiers to get
clues as to what a good build SDK might be. If desired, create a
project.properties file with a target=android-NNN line, where NNN is
your chosen build SDK. Or, you can address this in Eclipse later on.
Import the resulting project into Eclipse, and if needed adjust the
build SDK (Project > Properties > Android). Also, you will need to
attach to this library project any library projects it depends upon
(e.g., mediarouter-v7 depends upon appcompat-v7).

External libraries vs libs folder

Hey I'm pretty new to android studio, and relatively new to android development and it recently occurred to me that I'm not sure whether to put libraries in the libs folder or set them up as as an external library - what's the difference?
Most of what I've found online explains how to include jar files in the libs folder and then compile in the app gradle. This is what I've tended to do, but I've seen projects that work differently and I'm wondering what the protocol is for this.
Also how do you make an external library? Do you just place the jar file in it?
Thanks!

There is no way to create an external library directly in Android Studio. You add a library to your libs folder or add a dependency to your build.gradle, then you reimport the project, and it appears as an external library.
In other words, there is no difference - it's the same thing.

Library Project Supporting Eclipse and Android Studio

I'm working on a library project that provides access to a service. We started the project few months ago and we were supporting Eclipse only (since Android Studio was a prewview edition).
Now that Android Studio has become a "beta" version, and its popularity has increased greatly, we had the intention to support it as welll, but we are facing the problem of how to support both "styles" with the same base (project structure and code).
The library we are building has a UI that forced us to have the library as library project instead of just a simple jar. We have this project working with ANT to build the required files (jars) and packaging everthing in a library project.
Android Studio now introduces the .aar library files, that can also contain UI.
So our problem is finding examples of other library projects containing UI that are also supporting both IDE's. Wondering if someone else have face this same situation.
Is is possible to have a Library Project to support both IDEs? (Eclipse and Android Studio)

Thanks to #CommonsWare. When I looked at your projects I realize that we didn't need our project to be "Android Studio compatible". Since we wanted to share the project as an .aar file, I had only to make a build.gradle at the root of my library project and add the gradle folder (containing the gradle wrapper jars).
In this way I can use the console and create a .aar file using "./gradlew aR" command. Now I can distribute the library project for Eclipse users or the .aar file for Android Studio users.
I'm testing the .aar file, and the only problem I have right now is that classes inside a jar file within libs folder inside the .aar file are not recognized, just the classes present inside "classes.jar", but I think I would create another question here in SOF since is not relevant for this question.

How to distribute an Android Library

I've been spinning a jar for android library project and including this jar in my other apps. But on developer.android.com, I see this statement that I can't distribute a library in a jar:
You cannot export a library project to a JAR file
A library cannot be distributed as a binary file (such as a JAR file).
This will be added in a future version of the SDK Tools.
I really don't understand what does that mean.

It is possible to create an Android library project that does not
include source code. The limitations are:
You still have to ship the resources.
You have to rewrite your code to avoid using R. values, as they
will be wrong. You will have to look up all resource IDs using
getResources().getIdentifier() and/or reflection.
I have the instructions in The Busy Coder's Guide to Advanced Android
Development (http://commonsware.com/AdvAndroid), though the
instructions are new enough that none of my free versions have them.
Quoting some of the instructions from the current edition:
"You can create a binary-only library project via the following steps:
Create an Android library project, with your source code and such –
this is your master project, from which you will create a version of
the library project for distribution.
Compile the Java source (e.g., ant compile) and turn it into a JAR file
Create a distribution Android library project, with the same
resources as the master library project, but no source code
Put the JAR file in the distribution Android library project's libs/
directory
The resulting distribution Android library project will have everything a
main project will need, just without the source code."
Personally, I'd just wait a bit. I am hopeful that the official
support for library-projects-as-JARs will be available soonish.

It means that (at the current time) you must distribute your entire project folder. Rather than just a jar file like you can for java libraries.
When someone wants to use your library they will import your project into eclipse, and then in project properties->android they will add your project as an android library.
A few common ways used to distribute a Library project are by using git, or zipping your project folder and making it available online.

Is it possible to create jar that includes android functions?

As the topic indicates I would like to create a jar library that uses some android functions (no layouts) and that will be included in an Android project.
Is that possible and how?
From the research I've made I managed to include a simple jar file that uses pure Java (JAVA SE 1.6), but
when I tried creating a jar file I encountered the following exception when I tried to run the Andoid app: FATAL EXCEPTION: main
java.lang.NoClassDefFoundError: mylib.pleasework.amen
I tried including android.jar in my library and removing the java library, so that the jar file is build against android sdk, but it didn't work.
I tried including the jar file under a /libs folder as it is said to be the correct way to import jars in android projects from ADT v17 and after, but that didn't work either.
The jar I want to create will not use any resources (xml layouts, strings.xml) just Log.d and WifiManager.I am aware of Android Library Project but my library source is sensitive and I am afraid that it won't be safe if exposed in a Android library project. I was thinking of creating a jar and using ProGuard ( http://developer.android.com/tools/help/proguard.html ) obfuscate it.
I think I mentioned everything. Any help will be appreciated.
Thanks,
Thomas

As the topic indicates I would like to create a jar library that uses some android functions (no layouts) and that will be included in an Android project. Is that possible and how?
Use the jar command, or the <jar> Ant task. I am sure that there are ways to export a JAR from Eclipse, but I personally have never used them.
For example, in this GitHub repo I have a reusable component and a sub-project that is a sample app. My build.xml for the repo contains the following custom task:
<target name="jar" depends="debug">
<jar
destfile="bin/CWAC-WakefulIntentService.jar"
basedir="bin/classes"
/>
</target>
This generates a JAR file, that other Android applications can use by adding to their libs/ directories.
I am aware of Android Library Project but my library source is sensitive and I am afraid that it won't be safe if exposed in a Android library project.
It won't be safe exposed as a JAR, then, either. You can create an Android library project for public consumption that replaces the src/ tree's contents with a compiled JAR in libs/ in the library.

The way I did it in the end was: to create an Android Library project (check isLibrary checkbox in project properties) export it through Eclipse (right click on the project->export->jar file, careful to deselect all resources - res folder, androidmanifest.xml, *.png etc) and put it in the project you want by importing it under /libs folder. I don't know if this is the best solution but it worked for me.Used ADT r20, Eclipse 3.7.1, Android api level 7