Implementing Flutter PlatformChannels methods the smart way

FlutterPlugin.kt

package my.flutter.plugin

import io.flutter.plugin.common.MethodCall
import io.flutter.plugin.common.MethodChannel
import io.flutter.plugin.common.MethodChannel.MethodCallHandler
import io.flutter.plugin.common.MethodChannel.Result
import io.flutter.plugin.common.PluginRegistry.Registrar
import android.content.ContentValues.TAG
import android.util.Log
import java.lang.reflect.Method
import java.util.HashMap


class FlutterPlugin : MethodCallHandler {

    // ...
  
    // This method is getting called through a platform channel
    fun getPlatformVersion(call: MethodCall, result: Result) {
        result.success("Android ${android.os.Build.VERSION.RELEASE}")
    }

    // region MethodCallHandler
  
    // This map holds all available methods in this class
    private val methodMap = HashMap<String, Method>()

    // Handles the method call and calls the correct method in this class
    override fun onMethodCall(call: MethodCall, result: Result) {
        if (methodMap.isEmpty()) {
            fetchMethods()
        }

        val method = methodMap.get(call.method)
        if (null == method) {
            result.notImplemented()
            return
        }

        Log.v(TAG, "Method: " + call.method)
        val args = arrayOfNulls<Any>(2)
        args[0] = call
        args[1] = result

        try {
            method.invoke(this, *args)
        } catch (e: Exception) {
            result.error(call.method, e.message, e)
        }

    }

    // Fetches all methods in this class
    private fun fetchMethods() {
        val c = this::class.java
        val m = c.declaredMethods

        for (method in m) {
            methodMap[method.name] = method
        }
    }
    // endregion
}