diff --git a/app/src/main/java/keijumt/devandroid/common/Calculate.kt b/app/src/main/java/keijumt/devandroid/common/Calculate.kt
deleted file mode 100644
index 58ec5f4..0000000
--- a/app/src/main/java/keijumt/devandroid/common/Calculate.kt
+++ /dev/null
@@ -1,34 +0,0 @@
-package keijumt.devandroid.common
-
-import android.os.AsyncTask
-
-class Calculate(val callback: Callback<Int>) : AsyncTask<Int, Int, Int>() {
-
-    // ui thread
-    override fun onPreExecute() {
-        println("onPreExecute")
-    }
-
-    override fun doInBackground(vararg params: Int?): Int {
-        try {
-            println("doInBackground")
-            Thread.sleep(3000)
-        } catch (e: Exception) {
-
-        }
-        val value = params.get(0) ?: 1
-        return value * value
-    }
-
-    override fun onProgressUpdate(vararg values: Int?) {
-        println("onPorgressUpdate")
-    }
-
-    override fun onPostExecute(result: Int?) {
-        callback.execute(result)
-    }
-
-    interface Callback<T> {
-        fun execute(value: T?)
-    }
-}
\ No newline at end of file
diff --git a/app/src/main/java/keijumt/devandroid/common/Task.kt b/app/src/main/java/keijumt/devandroid/common/Task.kt
new file mode 100644
index 0000000..e2fdf8a
--- /dev/null
+++ b/app/src/main/java/keijumt/devandroid/common/Task.kt
@@ -0,0 +1,52 @@
+package keijumt.devandroid.common
+
+import android.os.AsyncTask
+import java.util.concurrent.CountDownLatch
+
+class Task(val callback: Callback<Int>) : AsyncTask<Void, Void, Int>() {
+
+    override fun doInBackground(vararg params: Void?): Int {
+        val countDownLatch = CountDownLatch(2)
+        var value1 = 0
+        var value2 = 0
+
+        val squireTask1 = SquareTask(object : Callback<Int> {
+            override fun execute(value: Int) {
+                value1 = value
+            }
+        }, countDownLatch)
+        val squareTask2 = SquareTask(object : Callback<Int> {
+            override fun execute(value: Int) {
+                value2 = value
+            }
+        }, countDownLatch)
+
+        squireTask1.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, 3)
+        squareTask2.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, 5)
+
+        countDownLatch.await()
+        return value1 * value2
+    }
+
+    override fun onPostExecute(result: Int?) {
+        callback.execute(result!!)
+    }
+
+    private class SquareTask(val callback: Callback<Int>, val countDownLatch: CountDownLatch) : AsyncTask<Int, Void, Int>() {
+        override fun doInBackground(vararg params: Int?): Int {
+            println("doInBackground, param is ${params.get(0)}")
+            val value = params.get(0)!!
+            return value * value
+        }
+
+        override fun onPostExecute(result: Int?) {
+            println("onPostExecute, result is ${result}")
+            callback.execute(result!!)
+            countDownLatch.countDown()
+        }
+    }
+
+    interface Callback<T> {
+        fun execute(value: T)
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/keijumt/devandroid/viewmodel/AsyncViewModel.kt b/app/src/main/java/keijumt/devandroid/viewmodel/AsyncViewModel.kt
index 84419cf..a7306a8 100644
--- a/app/src/main/java/keijumt/devandroid/viewmodel/AsyncViewModel.kt
+++ b/app/src/main/java/keijumt/devandroid/viewmodel/AsyncViewModel.kt
@@ -1,52 +1,23 @@
 package keijumt.devandroid.viewmodel
 
-import io.reactivex.Flowable
-import keijumt.devandroid.common.Calculate
-import kotlinx.coroutines.experimental.android.UI
-import kotlinx.coroutines.experimental.async
-import kotlinx.coroutines.experimental.delay
-import kotlinx.coroutines.experimental.launch
-import org.reactivestreams.Subscriber
+import android.os.AsyncTask
+import keijumt.devandroid.common.Task
 import javax.inject.Inject
 
 class AsyncViewModel @Inject constructor() : BaseViewModel() {
 
-    init {
-        println("start initialize")
-        val callback = object : Calculate.Callback<Int> {
-            override fun execute(value: Int?) {
-                println("callback execute value is ${value}")
-                println("call back thread is ${Thread.currentThread().name}")
+    fun async() {
+        val calc = Task(object : Task.Callback<Int> {
+            override fun execute(value: Int) {
+                println("callback is ${value}")
             }
-        }
-        val asyncCalc = Calculate(callback)
-        asyncCalc.execute(10)
-        println("finish initialize")
+        })
+        calc.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR)
+    }
 
-        launch(UI) {
-            val calc1 = async {
-                println("start async calc1")
-                delay(3000)
-                return@async 10
-            }
-            val calc2 = async {
-                println("start async calc2")
-                delay(3000)
-                return@async 6
-            }
-            val value1 = calc1.await()
-            val value2 = calc2.await()
-            println("value1 is ${value1}, value2 is ${value2}")
-            println("async await thread is ${Thread.currentThread().name}")
-        }
+    fun coroutine() {
+    }
 
-        val flowable = object : Flowable<Int>() {
-            override fun subscribeActual(s: Subscriber<in Int>?) {
-                println("start flowable")
-                Thread.sleep(3000)
-                s?.onNext(10)
-            }
-        }
-
+    fun rx() {
     }
 }
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment_async.xml b/app/src/main/res/layout/fragment_async.xml
index a976362..3e0022c 100644
--- a/app/src/main/res/layout/fragment_async.xml
+++ b/app/src/main/res/layout/fragment_async.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<layout>
+<layout xmlns:app="http://schemas.android.com/apk/res-auto">
 
     <data>
 
@@ -11,6 +11,33 @@
     <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:layout_width="match_parent"
         android:layout_height="match_parent">
-        
+
+        <Button
+            android:id="@+id/btn_asyncrask"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:onClick="@{() -> asyncViewModel.async()}"
+            android:text="asyncTask"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+        <Button
+            android:id="@+id/btn_rx"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:onClick="@{() -> asyncViewModel.rx()}"
+            android:text="rx"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/btn_asyncrask" />
+
+        <Button
+            android:id="@+id/btn_coroutine"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:onClick="@{() -> asyncViewModel.coroutine()}"
+            android:text="coroutine"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/btn_rx" />
+
     </android.support.constraint.ConstraintLayout>
 </layout>
\ No newline at end of file