title: How to setup ButterKnife plugin in Android Studio?
body: <p>I need to install the plugin Butter Knife. Where can I download it? I downloaded a .jar plugin (but not if the file is the one I need), I have installed but when I click on the option "generate" not the option to use butterknife appears. following a video tutorial I modified files Gradle build: I have them now as follows:</p>
  
  <pre><code>apply plugin: 'android-apt'
  apply plugin: 'com.android.application'
  
  
  android {
      compileSdkVersion rootProject.ext.compileSdkVersion
      buildToolsVersion rootProject.ext.buildToolsVersion
  
      defaultConfig {
          applicationId "calcursoedxleccion0.cal"
          minSdkVersion rootProject.ext.minSdkVersion
          targetSdkVersion rootProject.ext.targetSdkVersion
          versionCode 1
          versionName "1.0"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      testCompile 'junit:junit:4.12'
      compile "com.android.support:appcompat-v7:$rootProject.ext.supportLibraryVersion"
      compile "com.android.support:recyclerview-v7:$rootProject.ext.supportLibraryVersion"
      compile "com.android.support:support-v4:$rootProject.ext.supportLibraryVersion"
      compile "com.android.support:design:$rootProject.ext.supportLibraryVersion"
  
     // compile "com.jakewharton:butterknife:$rootProject.ext.butterKnifeVersion"
      compile "com.jakewharton:butterknife:$rootProject.ext.butterKnifeVersion"
  
  
     apt "com.jakewharton:butterknife-compiler:8.0.1"
  }
  </code></pre>
  
  <p>and</p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  
  buildscript {
      repositories {
          jcenter()
          mavenCentral()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:2.1.2'
          classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          jcenter()
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  
  ext{
  
      minSdkVersion = 16
      targetSdkVersion = 23
      compileSdkVersion = 23
      buildToolsVersion = '23.0.3'
  
      supportLibraryVersion = '23.3.0'
      butterKnifeVersion = '8.0.1'
  }
  </code></pre>
  
  <p>Gradle to synchronize I get this error:</p>
  
  <blockquote>
    <p>"The android android-library or plugin must be applied to the project"
    error (1.0)</p>
  </blockquote>
  
  <p>What am I doing wrong?</p>