kotlin View.OnClickListener? was expected

Question

I am trying to get this toggle button to work - All I want to do is print in console "hello" but am getting this error

Type mismatch: inferred type is Unit but View.OnClickListener? was expected

package com.radiomedia.drn1

import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity(){

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        playButton.setOnClickListener(
           print("hello")
         )

    }

}

Does this answer your question? [Android - How to achieve setOnClickListener in Kotlin?](https://stackoverflow.com/questions/44301301/android-how-to-achieve-setonclicklistener-in-kotlin) — Felix, Jul 27 '20 at 12:11

Shalu T D · Accepted Answer · 2020-07-27T12:14:03.410

3

Change setOnClickListener() method as any of the below options:

Option 1:

 playButton.setOnClickListener{
          print("hello")
    }

Option 2:

playButton.setOnClickListener(object : View.OnClickListener {
    override fun onClick(view: View?) {
        print("hello")
    }

})

Option 3:

playButton.setOnClickListener(View.OnClickListener { view ->
    print("hello")
})

edited Jul 27 '20 at 12:14

answered Jul 27 '20 at 12:04

Shalu T D

3,921
2
26
37

score 2 · Answer 2 · answered Jul 27 '20 at 12:05

2

You need to use braces instead, like this:

playButton.setOnClickListener{
       print("hello")
     }

answered Jul 27 '20 at 12:05

Shreemaan Abhishek

1,134
1
7
33

score 1 · Answer 3 · answered Jul 27 '20 at 12:05

1

either

    playButton.setOnClickListener {
       print("hello")
    }

or

 playButton.setOnClickListener(object: View.OnClickListener {
        override fun onClick(v: View?) {
            TODO("Not yet implemented")
        }

    })

answered Jul 27 '20 at 12:05

Blackbelt

156,034
29
297
305

kotlin View.OnClickListener? was expected

3 Answers3