diff --git a/app/src/main/java/keijumt/devandroid/common/Calculate.kt b/app/src/main/java/keijumt/devandroid/common/Calculate.kt
new file mode 100644
index 0000000..58ec5f4
--- /dev/null
+++ b/app/src/main/java/keijumt/devandroid/common/Calculate.kt
@@ -0,0 +1,34 @@
+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