Cordova Kotlin Plugin Tutorial

build-extras.gradle

android {
    sourceSets {
        main.java {
            srcDirs += 'src/main/kotlin'
        }
    }
}

KotlinToast.js

var exec = require('cordova/exec');

exports.start = function (arg0, success, error) {
    exec(success, error, 'KotlinToast', 'start', [arg0]);
};

KotlinToast.kt

package kotlintoast

import android.util.Log
import android.widget.Toast
import org.apache.cordova.*
import org.json.JSONArray
import org.json.JSONException

class KotlinToast : CordovaPlugin() {
    lateinit var context: CallbackContext

    @Throws(JSONException::class)
    override fun execute(action: String, data: JSONArray, callbackContext: CallbackContext): Boolean {
        context = callbackContext
        var result = true
        try {
            if (action == "start") {

                val input = data.getString(0)
                val output = "Kotlin says \"$input\""
                Toast.makeText(webView.context, output, Toast.LENGTH_LONG).show();
                callbackContext.success(output)
            } else {
                handleError("Invalid action")
                result = false
            }
        } catch (e: Exception) {
            handleException(e)
            result = false
        }

        return result
    }

    /**
     * Handles an error while executing a plugin API method.
     * Calls the registered Javascript plugin error handler callback.
     *
     * @param errorMsg Error message to pass to the JS error handler
     */
    private fun handleError(errorMsg: String) {
        try {
            Log.e(TAG, errorMsg)
            context.error(errorMsg)
        } catch (e: Exception) {
            Log.e(TAG, e.toString())
        }
    }

    private fun handleException(exception: Exception) {
        handleError(exception.toString())
    }

    companion object {

        protected val TAG = "KotlinToast"
    }
}

plugin.xml

<?xml version='1.0' encoding='utf-8'?>
<plugin id="vverh-digital-kotlin-toast" version="0.0.1" xmlns="http://apache.org/cordova/ns/plugins/1.0" xmlns:android="http://schemas.android.com/apk/res/android">
    <name>KotlinToast</name>
    <js-module name="KotlinToast" src="www/KotlinToast.js">
        <clobbers target="kotlin" />
    </js-module>
    <platform name="android">
        <config-file target="config.xml" parent="/*">        
            <preference name="GradlePluginKotlinEnabled" value="true" />
            <preference name="GradlePluginKotlinCodeStyle" value="official" />
            <preference name="GradlePluginKotlinVersion" value="1.3.50" />

            <feature name="KotlinToast">
                <param name="android-package" value="kotlintoast.KotlinToast" />
            </feature>
        </config-file>

        <source-file src="src/android/KotlinToast.kt" target-dir="src/main/kotlin/kotlintoast"/>
        <source-file src="src/android/build-extras.gradle" target-dir="."/>
    </platform>
</plugin>