Importing Facebook library in Android Studio: Could not find property 'ANDROID_BUILD_SDK_VERSION'

Question

I want to import a library project into my app but whenever I try to do so , Android Studio doesn't recognise it

It also gives me errors in build.gradle ..

The Library is : PagerSlidingTabStrip ....

Here are some pictures :

I have been trying to make it work for 3 days so far !! Please Help Me :)

EDIT:

apply plugin: 'android-library'

dependencies {
compile 'com.android.support:support-v4:19.0.0'
}

android {
compileSdkVersion Integer.parseInt(project.ANDROID_BUILD_SDK_VERSION)
buildToolsVersion project.ANDROID_BUILD_TOOLS_VERSION

defaultConfig {
    minSdkVersion 8
    targetSdkVersion Integer.parseInt(project.ANDROID_BUILD_TARGET_SDK_VERSION)
}

sourceSets {
    main {
        manifest.srcFile 'AndroidManifest.xml'
        java.srcDirs = ['src']
        res.srcDirs = ['res']
    }
}
}

 apply from: 'https://raw.github.com/chrisbanes/gradle-mvn-push/master/gradle-mvn-push.gradle'

EDIT2 :

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring project ':Sahertoday'.
> Could not resolve all dependencies for configuration ':Sahertoday:_debugCompile'.
> Could not find com.astuetz:pagerslidingtabstrip:1.0.1.
 Required by:
     Saher-3:Sahertoday:unspecified

* Try:
 Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get         more log output.

 BUILD FAILED

Answer 1

First of all, you can add this dependency to your project, without compiling the lib locally.

dependencies {
    compile 'com.astuetz:pagerslidingtabstrip:1.0.1'
}

Otherwise if you would like to compile this lib locally, you have to define these keys in gradle.properties in the root.

ANDROID_BUILD_TARGET_SDK_VERSION=19
ANDROID_BUILD_TOOLS_VERSION=19
ANDROID_BUILD_SDK_VERSION=19