how to set a counter in asynctask in android 4

import android.os.AsyncTask
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        var tv=abc as TextView
        MyAsync(tv).execute()
    }

    class MyAsync(var x:TextView) : AsyncTask<String, String, String>() {
        var j=0
        override fun doInBackground(vararg params: String?): String {
            
           for(j in 0..3) {
               Thread.sleep(2000)
 // Calls onProgressUpdate()
               publishProgress(j.toString())
           }
            return j.toString()
        }

        override fun onProgressUpdate(vararg values: String?) {
            x.text=values[0]
        }
    }
 }