Connecting Java or Kotlin to Flutter using MethodChannel

methodchannel.kt

package com.example.ourproject

import android.os.Bundle
import io.flutter.plugin.common.MethodChannel
import android.widget.Toast
import io.flutter.app.FlutterActivity
import io.flutter.plugins.GeneratedPluginRegistrant

class MainActivity: FlutterActivity() {
	private val CHANNEL = "ourproject.sendstring"

  	override fun onCreate(savedInstanceState: Bundle?) {
    	super.onCreate(savedInstanceState)
    	GeneratedPluginRegistrant.registerWith(this)

    	MethodChannel(flutterView, CHANNEL).setMethodCallHandler { call, result ->
      		if (call.method == "callSendStringFun") {
      			showHelloFromFlutter(call.argument("arg"))
      			val temp = sendString()
          		result.success(temp)
      		} else {
        		result.notImplemented()
      		}
    	}
  	}

  	private fun sendString(): String {
    	val stringToSend: String = "Hello from Kotlin"
    	return stringToSend
  	}

  	private fun showHelloFromFlutter(argFromFlutter : String?){
  		Toast.makeText(this, argFromFlutter, Toast.LENGTH_SHORT).show()
  	}
}

how to write in android code?

@sonthichaipks I wrote this code almost 3 years ago. You can read this article .

I got an error "Unhandled Exception: PlatformException" in release mode but can work on debug mode.
Could you help me plz ?