CODEWITHSUNDEEP
android-studiokotlinandroid-databinding
Jack Guo
Jack Guo

Reputation: 4664

Unresolved reference: BR (Android Studio)

My top level build.gradle:

buildscript {
    ext.kotlin_version = '1.2.41'
    ext.lifecycle_version = "1.1.1"
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.3'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

My project level build.gradle:

android {
    ...
    dataBinding {
        enabled = true
    }
}

dependencies {
    ...
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    implementation "android.arch.lifecycle:extensions:$lifecycle_version"
}

I also added android.databinding.enableV2=true to gradle.properties per Google documents (https://developer.android.com/topic/libraries/data-binding/start)

When I try to run, it shows Unresolved reference: BR error in my BaseViewHolder class. It seems that BR class has been properly generated but it also says duplicate class found in the file .../R.java when I mouse over the class name. What have I done wrong?

fun bind(obj: Any) {
        binding.setVariable(BR.obj, obj)
        binding.executePendingBindings()
}

Upvotes: 28

Views: 23717

Answers (5)

HaXxan Parhar
HaXxan Parhar

Reputation: 11

To anyone who faces this issue in Android Studio Chipmunk or above:

First add this in the App level Gradle to enable data binding. This is the obvious one but making sure just in case.

buildFeatures {
       dataBinding true
   }

Secondly add kotlin-kapt plugin in the App level Gradle.

plugins {
    id 'com.android.application'
    id 'org.jetbrains.kotlin.android'
    id 'kotlin-kapt'
}

BR class is generated but not referenced properly that is why Unresolved Reference is coming. By adding kotlin-kapt, it will fix this issue.

Upvotes: 1

VIVEK CHOUDHARY
VIVEK CHOUDHARY

Reputation: 546

I manually typed the line "binding.setVariable(BR.item, item)" and it worked for me. Android studio shows the suggestion of importing BR. Choose the one from your project. Also enable databinding = true in gradle.

Upvotes: 1

nyxee
nyxee

Reputation: 2811

Android Studio failed to import my BR class automatically. All solutions provided above failed. I just had to import the class manually, Android studio had created it correctly.

SAMPLE:

package your_packagename

import your_packagename.BR
import ...
...

I think this happened due to Copy and Paste. When i typed BR manually, Android Stdio did the Automatic Import.

Upvotes: 45

A. Steenbergen
A. Steenbergen

Reputation: 3440

For Android Studio 3.3, Gradle 3.3.0 and Databinding v2, the only line that needs to be added to fix this issue is in your (app's or modules) build.gradle:

apply plugin: "kotlin-kapt"

Upvotes: 60

Jack Guo
Jack Guo

Reputation: 4664

After researching quite a bit, turns out there are a couple things to add in order to use data binding library

project build.gradle

buildscript {
    ext {
        compiler_version = '3.1.3'
    }
    dependencies {
        classpath "com.android.tools.build:gradle:$compiler_version"
    }
}

app build.gradle

apply plugin: 'kotlin-kapt'

android {
    dataBinding {
        enabled = true
    }
}

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

kapt {
    generateStubs = true
}

I started to have some warnings after adding the data binding library, like 3rd-party Gradle plug-ins may be the cause and Classpath entry points to a non-existent location. But compiles and runs fine

Upvotes: 24

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