Issue with databinding using Kotlin for Android

问题:

I am trying to enable data binding for my Android project using Kotlin. I have Kotlin plugin enabled, but I am not able to enable data binding I keep getting the following error

Error:(66, 0) Could not find method kapt() for arguments [com.android.databinding:compiler:2.0.0-beta6] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler

I have the following dependencies for data binding in my gradle file

dependencies {
 ...
 kapt 'com.android.databinding:compiler:2.0.0-beta6'
} 

kapt {
    generateStubs = true
}

回答1:

Edit: With Kotlin 1.1 and Kapt3 it works slightly different:

in your project build.gradle:

buildscript {

   ext {
       ...
       plugin_version = "2.3.1"
       kotlin_version = "1.1.2-3"
       ...
   }

   ...

   dependencies {
       classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
       classpath "com.android.tools.build:gradle:$plugin_version"
       ...
   }
}

and in your app build.gradle:

    apply plugin: "kotlin-android"
    apply plugin: "kotlin-kapt"
    ...
    android {
      ...
      dataBinding {
            enabled = true
        }
      ...
    }

    dependencies {
       ...
       kapt "com.android.databinding:compiler:$plugin_version"
       ...
    }

It's really important that the databinding compiler version and the plugin version are identical.
Also note that with kapt3, you shouldn't use the generateStubs flag anymore.

---

Old Answer

Having the Android Studio plugin enabled isn't enough, you also need to adjust your gradle files a little bit (add and apply the kotlin-gradle-plugin) Here are excerpts of my gradle files with working Java and Kotlin Databinding

In your project build.gradle:

buildscript {
...
 dependencies {
   classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.0.5"
   classpath 'com.android.tools.build:gradle:2.2.3'
   ...
 }
}

and in your app build.gradle:

apply plugin: "kotlin-android"
...
android {
  ...
  dataBinding {
        enabled = true
    }
  ...
}
kapt {
    generateStubs = true
}
dependencies {
   ...
   kapt "com.android.databinding:compiler:2.2.0"
   ...
}

(I'm using a newer version of the databinding compiler here, you probably should do this as well)

回答2:

Try to include the missing blocks in your gradle files with the help of the following reference gradle file source.

App level Build.Gradle

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.3"
    defaultConfig {
        applicationId "com.example.adventure.abc"
        minSdkVersion 16
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

        vectorDrawables.useSupportLibrary = true
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    sourceSets {
        main.java.srcDirs += 'src/main/kotlin/com/dougritter/marvelmovies'
    }
    dataBinding {
        enabled = true
    }
}




kapt {
    generateStubs = true
}

dependencies {
    //Compatibility
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    kapt 'com.android.databinding:compiler:2.3.0'

    //Libraries
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:25.3.1'
    compile 'com.android.support:design:25.3.1'
    compile 'com.android.support:support-vector-drawable:25.3.1'
    compile 'com.android.support:support-v4:25.3.1'
    compile project(':domain')
    compile project(':androidutils')
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    compile 'com.jakewharton.timber:timber:4.5.1'


}

Project level Build.Gradle

    // Top-level build file where you can add configuration options common to all sub-projects/modules.


buildscript {
    ext.kotlin_version = '1.1.2-2'
    repositories {
        maven { url 'https://maven.google.com' }
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.0-alpha1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
// NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
        maven { url 'https://maven.google.com' }
        mavenCentral()
    }
}


task clean(type: Delete) {
    delete rootProject.buildDir
}