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kapt compiler issue in studio 3.2.1 with data binding and room

Build fails with error "cannot find symbol DataBindingComponent" in all generated binding classes.If I remove the room compiler dependency from my module gradle, then it unable to find room db at run time saying "Db_Impl does not exist".
def room_version = "1.1.1"
implementation "android.arch.persistence.room:runtime:$room_version"
//kapt "android.arch.persistence.room:compiler:$room_version"
//kapt 'com.android.databinding:compiler:3.2.1'

dependencies {
def room_version = "2.1.0-alpha06"
implementation "androidx.room:room-runtime:1.1.1"
annotationProcessor "androidx.room:room-compiler:1.1.1" // For Kotlin use kapt instead of annotationProcessor
// optional - Kotlin Extensions and Coroutines support for Room
implementation "androidx.room:room-ktx:1.1.1"
// optional - RxJava support for Room
implementation "androidx.room:room-rxjava2:1.1.1"
// optional - Guava support for Room, including Optional and ListenableFuture
implementation "androidx.room:room-guava:1.1.1"
// Test helpers
testImplementation "androidx.room:room-testing:1.1.1"
}

Try this..
add this dependency into app level gradle file.
implementation "android.arch.persistence.room:runtime:1.1.1"
annotationProcessor "android.arch.persistence.room:compiler:1.1.1"
more information refer this link
https://www.simplifiedcoding.net/android-room-database-example/

You are missing kotlin's annotation processor plugin. Add this to the top of your app level gradle file
apply plugin: 'kotlin-kapt'
and uncomment the data binding dependency. Sync after this.

Annotation processors must be explicitly declared now. - compiler-1.1.1.jar (android.arch.lifecycle:compiler:1.1.1)

I am trying to add below libraries into my app
ext {
roomLibraryVersion = '1.1.0'
lifeCycleVersion = '1.1.1'
}
//room data base
implementation "android.arch.persistence.room:runtime:$roomLibraryVersion"
implementation "android.arch.persistence.room:compiler:$roomLibraryVersion"
annotationProcessor "android.arch.persistence.room:compiler:$roomLibraryVersion"
//life cycle
implementation "android.arch.lifecycle:runtime:$lifeCycleVersion"
implementation "android.arch.lifecycle:compiler:$lifeCycleVersion"
implementation "android.arch.lifecycle:extensions:$lifeCycleVersion"
// rx android
implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
implementation "io.reactivex.rxjava2:rxjava:2.1.14"
implementation 'android.arch.persistence.room:rxjava2:1.1.0'
//paging
implementation 'android.arch.paging:runtime:1.0.0'
I am getting below exception while running the code. Can anybody please help me to solve this issue
Execution failed for task ':app:javaPreCompileDebug'.
> Annotation processors must be explicitly declared now. The following dependencies on the compile classpath are found to contain annotation processor. Please add them to the annotationProcessor configuration.
- compiler-1.1.1.jar (android.arch.lifecycle:compiler:1.1.1)
Alternatively, set android.defaultConfig.javaCompileOptions.annotationProcessorOptions.includeCompileClasspath = true to continue with previous behavior. Note that this option is deprecated and will be removed in the future.

Change:
implementation "android.arch.lifecycle:compiler:$lifeCycleVersion"
to:
annotationProcessor "android.arch.lifecycle:compiler:$lifeCycleVersion"

If you're using Kotlin, replace 'implementation' with 'kapt'
implementation "android.arch.lifecycle:extensions:$lifecycle_version"
kapt "android.arch.lifecycle:compiler:$lifecycle_version"
And put this at the top of your app level Gradle file
apply plugin: 'kotlin-kapt'

Cannot resolve symbol ViewModelProviders

I am working on Android ViewModel architecture component but I am getting the above mentioned error when trying to initialize a ViewModel in an AppCompatActivity.
import android.arch.lifecycle.ViewModelProviders;
ViewModelProviders.of(this).get(CounterViewModel.class);
There are a few questions and articles related to this, and they pointed towards adding the lifecycle:extensions and lifecycle:viewmodel dependencies in the app gradle file, but I am still getting the error.
implementation "android.arch.lifecycle:extensions:1.1.1"
implementation "android.arch.lifecycle:viewmodel:1.1.1"
annotationProcessor "android.arch.lifecycle:compiler:1.1.1"
The package android.arch.lifecycle does not contain the class ViewModelProviders and it only has ViewModelProvider class.
What else needs to be added to access the ViewModelProviders class?
Edit :
Dependencies in app/build.gradle:
dependencies {
implementation project(':lifecycle')
implementation project(':base')
implementation "android.arch.lifecycle:extensions:1.1.1"
implementation "android.arch.lifecycle:viewmodel:1.1.1"
annotationProcessor "android.arch.lifecycle:compiler:1.1.1"
}

android.arch.lifecycle:extensions:1.1.1 definitely has android.arch.lifecycle.ViewModelProviders. You can see it in Android Studio, if you open the "External Libraries" portion of the project tree and examine the library contents:
Some possible reasons for not finding the import include:
You have implementation "android.arch.lifecycle:extensions:1.1.1" in the wrong place (it should be in the dependencies closure of the module's build.gradle file, such as app/build.gradle)
You did not sync Android Studio with the Gradle build files (you are normally prompted to do this, but you can do it manually from File > Sync Project with Gradle Files from the Android Studio main menu)

You do not need both lifecycle:extensions and lifecycle:viewmodel in your build.gradle file, remove
implementation "android.arch.lifecycle:viewmodel:1.1.1"
and it should be fine now. Also, you may want to migrate to AndroidX and use the 2.0.0 versions of the library.

ViewModelProviders is now deprecated. Use ViewModelProvider instead.

If you are configuring in libary, you can modify the implementation to api

ViewModel in Kotlin: Unresolved Reference

I am trying to implement ViewModel in a 100% Kotlin app. Every piece of documentation I can find says I want to use this to get the ViewModel instance:
ViewModelProviders.of(this).get(CustomViewModel::class.java)
According to the docs, I should be able to import this with:
import android.arch.lifecycle.ViewModelProviders
This import is unresolved though. I am using the following in my build file:
def androidArchVersion = '1.1.1'
implementation "android.arch.lifecycle:viewmodel:$androidArchVersion"
implementation "android.arch.lifecycle:livedata:$androidArchVersion"
annotationProcessor "android.arch.lifecycler:compiler:$androidArchVersion"
testImplementation "android.arch.core:core-testing:$androidArchVersion"
Why can't I access ViewModelProviders?

Include the following as a dependency:
implementation "android.arch.lifecycle:extensions:1.1.1"
The equivalent AndroidX dependency is:
"androidx.lifecycle:lifecycle-extensions:VERSION"
in where VERSION can be replaced for Current Stable, Beta or Alpha values given in this official link
This dependency is for both ViewModel and LiveData and thus would not require you to give separate dependencies for the same either; i.e. the first two dependencies indicated by you can be replaced by the aforementioned lifecycle extensions dependency.

In my case I was missing :
implementation "androidx.fragment:fragment-ktx:1.1.0"

In addition to what Sup suggested, you'll have to correct lifecycler:compiler to lifecycle:compiler - the Gradle sync shouldn't even complete successfully with this typo.
Secondly, the standard android annotation processing ("annotationProcessor") doesn't really work with Kotlin. Instead, use Kotlin's kapt.
At the top of your build.gradle file, add the following:
apply plugin: 'kotlin-kapt'.
And in your dependencies section, replace occurences of annotationProcessor (like the above one) with kapt, e.g.
kapt "android.arch.lifecycle:compiler:1.1.1"

ViewModelProviders is deprecated in 1.1.0
Check this android docs
https://developer.android.com/topic/libraries/architecture/viewmodel
I am using 2.3.1 and add below dependency in build.gradle
implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'
implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.3.1'
implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.3.1'
Declare ViewModel in your Kotlin code as per below:
private val cartViewModel: CartViewModel by viewModels()
Still, if you facing below error like
Unresolved reference: viewModels
Then need to add below below dependency in build.gradle
implementation 'androidx.lifecycle:lifecycle-extensions-ktx:2.2.0'
implementation 'androidx.activity:activity-ktx:1.4.0'
implementation 'androidx.fragment:fragment-ktx:1.3.6'
OR
implementation 'androidx.navigation:navigation-fragment-ktx:2.3.5'
implementation 'androidx.navigation:navigation-ui-ktx:2.3.5'

I solve this by doing like this.
implement this dependency
implementation "android.arch.lifecycle:extensions:1.1.1"
then call my ViewModel class
homeViewModel = ViewModelProvider(this).get(HomeViewModel::class.java)

I faced this kind of problem in AndroidStudio 3.0.1 and solved by adding
following dependencies in the proper build.gradle:
implementation "android.arch.lifecycle:extensions:1.1.1"
annotationProcessor "android.arch.lifecycle:compiler:1.1.1"
version code may be different as AndroidStudio tells you if it differs.

If the above "adding/updating dependecies" did not resolve your issue then try to restart your android studio. It´s just to root, I do not see any major issue with it. Hope it helps.

Resolved with this dependency for me
implementation "androidx.lifecycle:lifecycle-extensions:2.2.0"

If someone want androidx, then, first - in build.gradle (app):
implementation "androidx.lifecycle:lifecycle-extensions:2.2.0"
Second - in file with code:
import androidx.lifecycle.ViewModelProvider
And third - use it:
ViewModelProvider(this).get(CustomViewModel::class.java)
Or use it like this (if needed ViewModelFactory):
ViewModelProvider(this, CustomViewModelFactory).get(CustomViewModel::class.java)

Not really sure why there are soo many solutions to this problem however while none of these worked for me, I did find a solution in my case.
implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.4.1"

This can also be resolved by targeting minSdkVersion to 21.
If you have minSdkVersion 21 or higher, you won't need implementation "android.arch.lifecycle:extensions:1.1.1".

android {
kotlinOptions {
jvmTarget = '1.8'
}
}
project e app level

Android Room Database - Unresolved reference #Entity and other annotations

I am using Android Room Persistence library (v.1.0.0-alpha1) in my app.
Although it is working fine, when I open model class (Kotlin Data class) in Android studio, it shows Unresolved reference for all annotations used for Room database like #Entity, #ColumnInfo etc. I tried changing version of arch library to 1.0.0-alpha5 but result was same.
In Lint inspection it is showing Remove deprecated symbol import for all imported annotations.AS was not showing this error previously.
How can I resolve this issue
Edit
Following are imports I have added in my build.gradle
compile "android.arch.persistence.room:runtime:1.0.0-alpha5"
compile "android.arch.persistence.room:rxjava2:1.0.0-alpha5"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha5"
kapt "android.arch.persistence.room:compiler:1.0.0-alpha5"

Here you have an example.
https://github.com/jsperk/PocRoom
Remember, you need add:
Gradle (Project)--> maven
Gradle (Module App) dependencies -->
implementation "android.arch.persistence.room:runtime:1.0.0"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0"
testImplementation "android.arch.persistence.room:testing:1.0.0"
implementation "android.arch.persistence.room:rxjava2:1.0.0"

In my project, I have this question cause I'm using
android.arch.lifecycle:livedata:1.1.1
than no matter using room with version 1.1.1 or 1.0.0, it still can't find the android.arch.persistence.room.Entity.
I've searched for a long time, till I found that, when I delete the LiveData implementation, the problem solved. Then I notice that, the version of these two libraries conflict. At last, I use the same version of 1.1.0 for livedata and room (since livedata have no version of 1.0.0), and solved it.
def arch_version = "1.1.0"
implementation "android.arch.persistence.room:runtime:$arch_version"
annotationProcessor "android.arch.persistence.room:compiler:$arch_version"
implementation "android.arch.persistence.room:rxjava2:$arch_version"
implementation "android.arch.persistence.room:common:$arch_version"
implementation "android.arch.lifecycle:livedata:$arch_version"
implementation "android.arch.lifecycle:extensions:$arch_version"

Adding these dependencies to your Gradle(Module App) file will solve it:-
implementation "android.arch.persistence.room:runtime:1.1.1"
annotationProcessor "android.arch.persistence.room:compiler:1.1.1"
testImplementation "android.arch.persistence.room:testing:1.1.1"
implementation "android.arch.persistence.room:rxjava2:1.1.1"