SMS sending with Twilio and Android

Question

I have the Android project. I use Gradle and Kotlin.
I need to realize the SMS sending mechanism with Twilio.

I used this manual: How to Send an SMS from Android

So, I have created the Backend.
Here is the build.gradle for Backend:

group 'com.my.app'
version '1.0-SNAPSHOT'

buildscript {
    repositories { jcenter() }
    dependencies {
        classpath 'com.github.jengelman.gradle.plugins:shadow:1.2.3'
    }
}

apply plugin: 'java'
apply plugin: 'application'
apply plugin: 'com.github.johnrengelman.shadow'

sourceCompatibility = 1.8
mainClassName = 'SMSBackend'

repositories {
    mavenCentral()
}

dependencies {
    testImplementation group: 'junit', name: 'junit', version: '4.12'
    implementation 'com.sparkjava:spark-core:2.6.0'
    implementation group: 'com.twilio.sdk', name: 'twilio', version: '7.9.0'
    implementation 'org.slf4j:slf4j-simple:1.6.1'
}

And here is the main activity - SMSBackend.java

import com.twilio.http.TwilioRestClient;
import com.twilio.rest.api.v2010.account.Message;
import com.twilio.rest.api.v2010.account.MessageCreator;
import com.twilio.type.PhoneNumber;
import static spark.Spark.*;

import static spark.Spark.get;
import static spark.Spark.post;

public class SMSBackend {
    public static void main(String[] args) {
        get("/", (req, res) -> "Hello, World!");

        TwilioRestClient client = new TwilioRestClient.Builder(System.getenv("AC749....d462247b104a"), System.getenv("096e4788......ed95cc36c")).build();

    post("/sms", (req, res) -> {
        String body = req.queryParams("Body");
        String to = req.queryParams("To");
        String from = "+15037381694";

        Message message = new MessageCreator(
                new PhoneNumber(to),
                new PhoneNumber(from),
                body).create(client);

        return message.getSid();
    });
    }
}

After that, I use ngrok in order this app becomes available externally.

I type the command:

ngrok http 4567

And have an output as the link below:

And now I go to my Android application. I need to enter my telephone number, click on the button and after that receive the SMS.
For this, I put the link from ngrok into my activity.

My MyActivity.kt

package com.my.app

import android.content.Context
import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.Menu
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import android.widget.Toast

import java.io.IOException;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.Response;

class MyActivity : AppCompatActivity() {

private val mClient = OkHttpClient()
private val mContext = getApplicationContext()
private val message = resources.getString(R.string.textSMS)
private val userPhoneNumber = findViewById(R.id.editText) as EditText
private val buttonSend = findViewById(R.id.button) as Button

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

        buttonSend.setOnClickListener {
            post(("https://2b722554.ngrok.io/sms"), object : Callback {
                        override fun onFailure(call: Call, e: IOException) {
                            e.printStackTrace()
                        }

                        @Throws(IOException::class)
                        override fun onResponse(call: Call, response: Response) {
                            runOnUiThread(object : Runnable {
                                public override fun run() {
                                    userPhoneNumber.setText("")
                                    message.setText("")
                                    Toast.makeText(applicationContext, "SMS Sent!", Toast.LENGTH_SHORT).show()
                                }
                            })
                        }

            })
    }

}

@Throws(IOException::class)
    internal fun post(url: String, callback: Callback): Call {
        val formBody = FormBody.Builder()
                .add("To", userPhoneNumber.getText().toString())
                .add("Body", message.getText().toString())
                .build()
             val request = Request.Builder()
                .url(url)
                .post(formBody)
                .build()
    val response = mClient.newCall(request)
    response.enqueue(callback)
    return response
}

So, when I run my application on the emulator or real device I can enter the number but the button is not working.
But I can send and receive the SMS from Twilio site, so, my Twilio number is Ok.

What am I missing?

UPD. I have changed all my kotline code. Now my application doesn't run on the emulator or real device

Answer 1

Looking at the click listener you add to the button:

buttonSend.setOnClickListener {
  fun onClick(v: View) {
    ...
  }
}

this will only create a local function called onClick but it won't execute any code inside the click listener. To get this to work, you need to remove all local function declarations and execute the request right in the click listener body:

buttonSend.setOnClickListener {
  post(getString("https://07eca790.ngrok.io/sms") ...
}

Here's a reference: Local Functions