Unresolved reference:ActivityMainBinding

Question

I know that this question have been asked before but I tried all the answers given and I still got nothing. I'm trying to define a var binding:ActivityMainBinding and I got an error

Unresolved reference:ActivityMainBinding

Here is a part of my mainActivity

import com.kolydas.aboutme.databinding.ActivityMainBinding //error

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding //error
    //....
}

Here is my App build.gradle

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

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.kolydas.aboutme"
        minSdkVersion 19
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

    dataBinding{
        enabled = true  //enable data binding
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    kapt "com.android.databinding:compiler:3.4.0"
}

And of course in my xml file i have the layout /layout tags in the beginning and in the end.

Solution 1

None of the suggestions worked for me, because the correct way to resolve this issue is to put (app level build.gradle)

buildFeatures{
   dataBinding = true
   viewBinding = true
}

Solution 2

Sometimes all you need is clean and rebuild the project.

Build -> Clean Project 
Build -> Rebuild Project

This would be enough for generating the binding classes.

Generated binding classes

Solution 3

Try to add in build.gradle (Module:app)

buildFeatures {
   viewBinding true
}

Solution 4

It's not about the Gradle file. It is about the XML file.

First, make sure that your layout tag contains just this line:

xmlns:android="http://schemas.android.com/apk/res/android"

or these lines:

xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"

Then rebuild the project.

Solution 5

Just to sum up all useful actions:

1. Check if you got top-level <layout> tag in respective .xml file.
2. Verify build.gradle (app) if binding enabled=true in android section.

3. Verify imports in activity file:

   import android.databinding.DataBindingUtil
   import com.example.[YOUR_APP_NAME].databinding.ActivityMainBinding
   

4. Try to rebuild project Build > Rebuild Project after every action just to refresh and check the results.

   Good Luck! It's just beginning of this Android journey:)

View more solutions

Comments

[Rob Ert]

You can also try to reboot your IDE if it's not refreshing code, but it extremely rare.

[TarekB]

in case someone needs to see the code here is the github link github.com/udacity/andfun-kotlin-android-trivia/blob/…

[One Face]

This worked for view binding. Had to include apply plugin: 'kotlin-kapt' in the gradle file.

[B. Go]

Please avoid images of code! You can format code in your answer with the {} button

[user1283182]

For some questions about unresolved FragmentTitleBinding, please try to replace the default <FrameLayout> tag with <layout> tag in your res/layout/fragment_title.xml

[Bardo]

I had layout_height and width on my Layout root node, but when only namespace attributes where left, the system proposed me to convert it to databinding layout. I cleaned and rebuild project, and the problem got solved.

[cluster1]

Yep. That has worked for me! No actual configuration changes necessary. Thanks a lot.

[thebluepandabear]

Worked like a charm! Thanks :)

[mufazmi]

While this code may answer the question, providing additional context regarding how and/or why it solves the problem would improve the answer's long-term value.

[HelloWorld]

This looks like the "official" way to do it as it is described in Android Codelabs.

[SMBiggs]

Yes, this finally lets me add the correct import statement. :)

[Dieglock]

In my case I had the wrong context on the xml file. Thanks.

[Admin]

Doing this all the time is boring. Isn't there a better way to do this?

[t0in4]

for Kotlin add in plugins { id 'kotlin-kapt' }