ButterKnife @OnClick annotation not working in Kotlin fragment

Question

I like the readability of the @OnClick attribute from ButterKnife: hence, I'm using it even in Kotlin. Unfortunately, the click handler just isn't being fired when I click. Am I missing something? Is there something I have to do to integrate the click listener in kotlin?

Fragment:

import kotlinx.android.synthetic.main.fragment_profile.*

class ProfileFragment : Fragment() {

    override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        val view = inflater!!.inflate(R.layout.fragment_profile, container, false)
        ButterKnife.bind(this, view)


        return view
    }

    companion object {
        fun newInstance(): ProfileFragment {
            return ProfileFragment()
        }
    }

    @OnClick(R.id.fab)
    public fun onFab() {
        Toast.makeText(activity, "ABC", Toast.LENGTH_LONG).show()
        Snackbar.make(container, "Hey there!", Snackbar.LENGTH_LONG).show()
    }
}

Layout

<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="300dp">

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="16dp"
    android:layout_gravity="bottom|right|end"
    android:src="@drawable/ic_edit"
    app:fabSize="normal"
    app:elevation="6dp"
    app:pressedTranslationZ="12dp"/>

</android.support.design.widget.CoordinatorLayout>

Answer 1

If you are using Kotlin, replace annotationProcessor with kapt

The reason behind it is that may be you are using dependencies like this :

dependencies {
  implementation 'com.jakewharton:butterknife:10.1.0'
  annotationProcessor 'com.jakewharton:butterknife-compiler:10.1.0'
}

replace it like this:

dependencies {
  implementation 'com.jakewharton:butterknife:10.1.0'
  kapt'com.jakewharton:butterknife-compiler:10.1.0'
}