Gradle

//include ':FragmentNavigator'
//project(':FragmentNavigator').projectDir = new File(settingsDir, '../../Libraries/FragmentNavigator/library')

compile project(path: ':FragmentNavigator')

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Gradle library
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build.gradle

apply plugin: 'java'
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
}

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build.gradle

apply plugin: 'com.android.library'
android {
    compileSdkVersion 23    buildToolsVersion "23.0.3"
    defaultConfig {
        minSdkVersion 14        targetSdkVersion 23        versionCode 1        versionName "1.0"    }
    buildTypes {
        release {
            minifyEnabled false            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:23.4.0'}

settings.gradle

include ':app', ':lib', ':mylibrary' //Include library


local.properties
ndk.dir=D\:\\Android\\AndroidSDK\\ndk-bundlesdk.dir=D\:\\Android\\AndroidSDK