1,install inteliji idea plugin:Kotlin;

2,JAVA:

3,Android:

step 1:double click Shift in android studio, enter Convert Java F Kotlin;

step 2:double click Shift in android studio,enter configure Kotlin;

step 3:add classpath “org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version” in app gradle like

buildscript {
  ext.kotlin_version = '0.14.451'
  repositories {
     mavenCentral()
  }
  dependencies {
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
  }
}
    ```