import kotlinx.android.synthetic.main.activity_main2.*然后
tv!!.text = "你好" tv!!.textSize = 12.5f但是,程序会报错
Error:(16, 9) Unresolved reference: btn Error:(15, 9) Unresolved reference: tv Error:(14, 9) Unresolved reference: tv Error:(7, 8) Unresolved reference: kotlinx Error:Execution failed for task ':app:compileDebugKotlin'. > Compilation error. See log for more details后来google到解决办法
classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"然后
apply plugin: 'kotlin-android-extensions'完美解决