1、在项目的build.gradle下

buildscript {

    ext {

        compileSdkVersion =29

        buildToolsVersion ='29.0.0'

        targetSdkVersion =29//用最新

        minSdkVersion =19

        versionCode =1

        versionName ='1.0.0'

        kotlinVersion ='1.3.10'//升级到1.3.10

    }

    dependencies {

        classpath'com.android.tools.build:gradle:3.4.1'//升级到最新

        classpath"org.jetbrains.kotlin:kotlin-gradle-plugin:$rootProject.kotlinVersion"

        classpath'com.jakewharton:butterknife-gradle-plugin:9.0.0-rc3'//控件自动生成插件(9.0.0-rc2或以上)

    }

}

2、app下的build.gradle下

dependencies {

   //这个在app写，防止绑定控件报空

    annotationProcessor'com.jakewharton:butterknife-compiler:9.0.0-rc3'

    implementation'com.jakewharton:butterknife:9.0.0-rc3'

    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$rootProject.kotlinVersion"//改成jdk

}