Kotlin学习教程之协程Coroutine

 dependencies { 
  implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:0.22.5'  
  implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:0.19.3" 
 }

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 tools:context=".coroutine.CoroutineActivity">

 <TextView
  android:id="@+id/tvHello"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" />
</android.support.constraint.ConstraintLayout>

class CoroutineActivity : AppCompatActivity() {
 override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
  setContentView(R.layout.activity_coroutine)
  setup()
 }

 fun setup() {
  launch(UI) { // launch coroutine in UI context
   for (i in 10 downTo 1) { // countdown from 10 to 1
    tvHello.text = "Countdown $i ..." // update text
    delay(1000) // wait half a second
   }
   tvHello.text = "Done!"
  }
 }
}

class CoroutineActivity : AppCompatActivity() {
 lateinit var job:Job
 override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
  setContentView(R.layout.activity_coroutine)
  setup()
 }

 fun setup() {
  job = launch(CommonPool) { // launch coroutine in UI context
   for (i in 10 downTo 1) { // countdown from 10 to 1
    tvHello.text = "Countdown $i ..." // update text
    delay(1000) // wait half a second
   }
   tvHello.text = "Done!"
  }
 }

 override fun onPause() {
  super.onPause()
  job.cancel()
 }
}

launch(UI)

launch(){...}

launch(CommonPool){...}

 private fun createPlainPool(): ExecutorService {
  val threadId = AtomicInteger()
  return Executors.newFixedThreadPool(defaultParallelism()) {
   Thread(it, "CommonPool-worker-${threadId.incrementAndGet()}").apply { isDaemon = true }
  }
 }

 private fun defaultParallelism() = (Runtime.getRuntime().availableProcessors() - 1).coerceAtLeast(1)