error: cannot find symbol class for add kotlin class into java class in android studio 3.0 stable - gradle

Question

i use android studio 3.0 and some old java class Convert Java to Kotlin. after that Kotlin class cant import in java class!
in below you can see my gradle and a picture of my error.
module build.grade
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.0.0'
classpath 'com.google.gms:google-services:3.1.0'
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
jcenter()
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
in app level build.gradle in normally i use gradle code and in android 3.0 i think we need any thing
apply plugin: 'com.android.application'
android {
compileSdkVersion 25
buildToolsVersion '26.0.2'
defaultConfig {
applicationId "com.idehnavazan.beautifierclient"
minSdkVersion 14
targetSdkVersion 25
versionCode 1
versionName "1.0"
multiDexEnabled true
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
dataBinding {
enabled = true
}
}
repositories {
mavenCentral()
jcenter()
maven { url 'https://maven.google.com' }
maven { url 'https://jitpack.io' }
}
dependencies {
compile 'com.android.support:multidex:1.0.1'
compile 'com.android.support:appcompat-v7:25.3.1'
compile 'com.github.rey5137:material:1.2.2'
compile 'com.android.support:cardview-v7:25.3.1'
}
apply plugin: 'com.google.gms.google-services'

Answer 1

To work with Kotlin files you need to add Kotlin to your project.
project/build.gradle
buildscript {
ext.kotlinVersion = '1.1.51'
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.0.0'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
}
}
project/module/build.gradle
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
dependencies {
implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"
}
What's next
Since you're using support library 25.3.1 and Android plugin 3.0.0 your next question will probably be this: style attribute '#android:attr/windowEnterAnimation' not found.

Answer 2

I have added all kotlin classes in separate folder and it work for me!
Keep your java classes separate from kotlin. I was having
app:compileDebugJavaWithJavac Kotlin class calling from java: error: cannot find symbol
compile time error.

Answer 3

My issue was that I have imported a submodule using
testImplementation instead of implementation inside of module gradle file that is declaring your module as a dependency.
Changing the dependency declaration fixed it for me.

Answer 4

I am also new to kotlin/android and was using ViewBinding. I was renaming an xml-file when this type of error occured. I just added:
dataBinding {
enabled = true
}
to the build.gradle(module)-file and it now works. To be honest, I never understood the difference between view- and data-binding

Answer 5

kotlin/android and was using ViewBinding.
just add this inside build.gradle(module)-file
viewBinding{
enabled = true
}