Warning: warning: Supported source version 'RELEASE_7' from annotation processor 'android.arch.lifecycle.LifecycleProcessor' less than -source '1.8'

Question

Trying to build a sample using Android Studio 3 Canary 5 with Architecture Components and Kotlin gives this warning.

Can anyone tell me the reason?

Thanks, Ove

Edit #1: This is a sample made some time ago by Dan Lew

https://github.com/dlew/android-architecture-counter-sample

build.gradle:

apply plugin: 'com.android.application' apply plugin: 'kotlin-android' apply plugin: 'kotlin-kapt'  android {     compileSdkVersion 25     buildToolsVersion rootProject.ext.buildToolsVersion     defaultConfig {         applicationId "net.danlew.counter"         minSdkVersion 23         targetSdkVersion 25         versionCode 1         versionName "1.0"         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"     }     buildTypes {         release {             minifyEnabled false             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'         }     } }  dependencies {     compile fileTree(dir: 'libs', include: ['*.jar'])     androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {         exclude group: 'com.android.support', module: 'support-annotations'     })     compile "com.android.support:appcompat-v7:${rootProject.ext.supportLibVersion}"     compile "com.android.support:recyclerview-v7:${rootProject.ext.supportLibVersion}"     compile "com.android.support:design:${rootProject.ext.supportLibVersion}"     compile "com.android.support:cardview-v7:${rootProject.ext.supportLibVersion}"     compile 'com.android.support.constraint:constraint-layout:1.0.2'     testCompile 'junit:junit:4.12'      compile "android.arch.lifecycle:extensions:${rootProject.archLifecycleVersion}"     compile "android.arch.persistence.room:runtime:${rootProject.archRoomVersion}"     compile "android.arch.persistence.room:rxjava2:${rootProject.archRoomVersion}"     kapt "android.arch.lifecycle:compiler:${rootProject.archLifecycleVersion}"     kapt "android.arch.persistence.room:compiler:${rootProject.archRoomVersion}"     compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"      String butterKnifeVersion = '8.5.1'     compile "com.jakewharton:butterknife:$butterKnifeVersion"     kapt "com.jakewharton:butterknife-compiler:$butterKnifeVersion"      compile 'io.reactivex.rxjava2:rxjava:2.1.0'      String daggerVersion = '2.10'     compile "com.google.dagger:dagger:$daggerVersion"     kapt "com.google.dagger:dagger-compiler:$daggerVersion"      String rxBindingVersion = '2.0.0'     compile "com.jakewharton.rxbinding2:rxbinding:$rxBindingVersion"     compile "com.jakewharton.rxbinding2:rxbinding-kotlin:$rxBindingVersion"      compile 'com.jakewharton.timber:timber:4.5.1'      compile 'com.jakewharton.rxrelay2:rxrelay:2.0.0' }  repositories {     mavenCentral() } 

Answer 1

There is a Java 8 annotation processor now arch components are stable so replace:

"android.arch.lifecycle:compiler:${rootProject.archLifecycleVersion}" 

with

"android.arch.lifecycle:common-java8:1.0.0"