How to integrate ZXing Library to Android Studio for Barcode Scanning?

My build.gradle file like this:

apply plugin: 'com.android.application'android {    compileSdkVersion 21    buildToolsVersion "21.1.2"    defaultConfig {        applicationId "com.myapplication2"        minSdkVersion 16        targetSdkVersion 21        versionCode 1        versionName "1.0"    }    buildTypes {        release {            minifyEnabled false            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'        }    }}repositories {    mavenCentral()    maven {        url "https://raw.github.com/embarkmobile/zxing-android-minimal/mvn-repo/maven-repository/"    }}dependencies {    compile fileTree(dir: 'libs', include: ['*.jar'])    compile 'com.android.support:appcompat-v7:21.0.3'    // Supports Android 4.0.3 and later (API level 15)    compile 'com.embarkmobile:zxing-android-minimal:2.0.0@aar'    // Supports Android 2.1 and later (API level 7), but not optimal for later Android versions.    // If you only plan on supporting Android 4.0.3 and up, you don't need to include this.    compile 'com.embarkmobile:zxing-android-legacy:2.0.0@aar'    // Convenience library to launch the scanning and encoding Activities.    // It automatically picks the best scanning library from the above two, depending on the    // Android version and what is available.    compile 'com.embarkmobile:zxing-android-integration:2.0.0@aar'    // Version 3.0.x of zxing core contains some code that is not compatible on Android 2.2 and earlier.    // This mostly affects encoding, but you should test if you plan to support these versions.    // Older versions e.g. 2.2 may also work if you need support for older Android versions.    compile 'com.google.zxing:core:3.0.1'}