java.lang.IllegalStateException: Could not find method count(View) in a parent or ancestor Context for android:onClick attribute defined on view class

Question

The app keeps crashing whenever I click the count or reset button I think that the app is not recognizing the onclick methods count and reset I tried the same using java but it was working fine using java so the problem must be with kotlin Is there any solution for this probelm? or should I follow any alternative methods?

package com.example.a39kotlinfun

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.TextView

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


    var textView = findViewById<TextView>(R.id.textView)

    var count = 0

    fun count(view : View){
        count += 1
        textView.text = count.toString()
    }

    fun reset(view : View){
        count = 0
        textView.text = "0"
    }
}

}

XML:

 <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="50dp"
    android:layout_marginBottom="400dp"
    android:text="Hello World!"
    android:textSize="36sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="55dp"
    android:layout_marginLeft="55dp"
    android:layout_marginTop="111dp"
    android:layout_marginBottom="247dp"
    android:onClick="count"
    android:text="count"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/textView" />

<Button
    android:id="@+id/button2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="111dp"
    android:layout_marginEnd="51dp"
    android:layout_marginRight="51dp"
    android:layout_marginBottom="247dp"
    android:onClick="reset"
    android:text="reset"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/textView" />

</androidx.constraintlayout.widget.ConstraintLayout>

Logcat:

java.lang.IllegalStateException: Could not find method count(View) in a parent or ancestor Context for android:onClick attribute defined on view class com.google.android.material.button.MaterialButton with id 'button'
    at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:447)
    at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:405)
    at android.view.View.performClick(View.java:7189)
    at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1119)
    at android.view.View.performClickInternal(View.java:7166)
    at android.view.View.access$3500(View.java:819)
    at android.view.View$PerformClick.run(View.java:27682)
    at android.os.Handler.handleCallback(Handler.java:883)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loop(Looper.java:224)
    at android.app.ActivityThread.main(ActivityThread.java:7592)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)

Answer 1

Move the count and reset methods out of onCreate method.

class MainActivity : AppCompatActivity() {

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

       var textView = findViewById<TextView>(R.id.textView)
    }

    var count = 0

    fun count(view : View){
        count += 1
        textView.text = count.toString()
    }

    fun reset(view : View){
        count = 0
        textView.text = "0"
    }
}

In any case setting android:onClick should be avoided and the best solution is to use:

val button = findViewById<Button>(R.id.button)
button.setOnClickListener {
    count += 1
    textView.text = count.toString()
}