[Kotlin] AsyncTask

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">

    <TextView
        android:id="@+id/tvText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Ready"
        android:textSize="30dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent" />

    <Button
        android:id="@+id/btnStart"
        android:layout_width="180dp"
        android:layout_height="80dp"
        android:textAllCaps="false"
        android:text="Start"
        android:textSize="16dp"
        android:layout_marginTop="30dp"
        app:layout_constraintTop_toBottomOf="@+id/tvText"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

activity_main.xml

 

 

 

 

 

 

MyAsyncTask.kt

package com.jwsoft.kotlinproject

import android.os.AsyncTask
import android.widget.TextView
import java.lang.Exception

class MyAsyncTask(var tvText: TextView) : AsyncTask<Void, Int, Boolean>() {

    override fun onPreExecute() {
        super.onPreExecute()
    }

    override fun doInBackground(vararg params: Void?): Boolean {
        for (i in 1..50) {
            try {
                Thread.sleep(5)
            } catch (e: Exception) {
                e.printStackTrace()
            }
            publishProgress(i)
        }

        return true
    }

    override fun onProgressUpdate(vararg values: Int?) {
        super.onProgressUpdate(*values)
        tvText.text = values[0].toString() + " 초 경과"
    }

    override fun onPostExecute(result: Boolean?) {
        super.onPostExecute(result)
    }

    override fun onCancelled(result: Boolean?) {
        super.onCancelled(result)
    }

}

 

 

 

 

 

 

 

MainActivity.kt

package com.jwsoft.kotlinproject

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

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

        var myAsyncTask = MyAsyncTask(tvText)

        btnStart.setOnClickListener {
            myAsyncTask.execute()
        }
    }

}

실행 결과

 

한 번 더 클릭하면 에러 발생!

에러 발생

하나의 객체이므로 재사용 불가능.

execute() 한 번만 쓸 수 있음.

객체를 새로 생성해야 함.

 

(참고. Thread 객체도 start() 한 번만 사용 가능)

(그런 의미에서 Thread 객체랑 AsyncTask 객체랑 비슷하네)

---

MainActivity.kt

package com.jwsoft.kotlinproject

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

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

        btnStart.setOnClickListener {
            var myAsyncTask = MyAsyncTask(tvText)
            myAsyncTask.execute()
        }
    }

}

실행 결과