title: Fetching a URL in Android Kotlin asynchronously
body: <p>So I'm trying to write a very simple Android app that fetches a response from a URL when a button gets pressed. The kotlin Android extensions have been advertised as a drop-in replacement for the boilerplate necessary in Java, so I tried my hand. Here's what I tried so far:</p>
  
  <pre><code>package com.example.susemihl.myapplication
  
  import android.os.Bundle
  import android.support.v7.app.AppCompatActivity
  import android.widget.TextView
  import kotlinx.android.synthetic.main.activity_main.*
  import kotlinx.coroutines.experimental.CommonPool
  import kotlinx.coroutines.experimental.async
  import kotlinx.coroutines.experimental.runBlocking
  import java.net.URL
  
  suspend fun fetch_url(url: String): String {
      return URL(url).readText()
  }
  
  fun fetch_async(url: String, view: TextView) = runBlocking {
      val result = async(CommonPool) { fetch_url(url) }
      view.setText(result.await())
  }
  
  class MainActivity : AppCompatActivity() {
  
      override fun onCreate(savedInstanceState: Bundle?) {
          super.onCreate(savedInstanceState)
          setContentView(R.layout.activity_main)
          mainTextView.setText("Hello there.")
          mainButton.setOnClickListener {
              mainButton.setText("Check again.")
              fetch_async("https://random-app.appspot.com/", 
                          mainTextView)
          }
  
      }
  }
  </code></pre>
  
  <p>This worked intermittently, but is now completely broken. There is no response to the button click. Print-debugging shows me that the thread gets executed, but seems to hang on the readText() call. Anything stupid I'm doing wrong here?</p>