如何在Android Kotlin中添加或查找主活动之外的文本视图

Question

包com.example.asyntask

导入android.content.ContentValues.TAG

导入android.os.AsyncTask

导入androidx.appcompat.app.AppCompatActivity

导入android.os.Bundle

导入android.util.Log

导入android.widget.Button

导入android.widget.Text查看

导入kotlinx.android.synthetic.main.activity_main.*

类MainActivity:AppCompatActivity((｛

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
btnStart.setOnClickListener {
val tvCounter=findViewById<TextView>(R.id.tvCounter)
CountTask().execute(5)
}
}

}

class CountTask((：异步任务<Int，Int，单位>((｛

private val tag: String? = "Async"
override fun doInBackground(vararg params: Int?) {
Log.d(tag, "doInBackground: started")
val n: Int = params[0]!!
for (i in 0 until n) {
wait1Sec()
publishProgress(i)
}
}
private fun wait1Sec():Unit{
val start =System.currentTimeMillis()
while(System.currentTimeMillis()<start+1000){}
}

override fun onProgressUpdate(vararg values: Int?) {
super.onProgressUpdate(*values)
//WANT TO WRITE TEXT IN TEXT VIEW BUT HOW TO GET VIEW HERE
}

}

Answer 1

请尝试创建从异步任务到主活动的进度更新回调

类似：

Interface UpdateListener{
fun onProgressUpdate(progress:Int);
}
class CountTask(val listener:UpdateListener) : AsyncTask<Int, Int, Unit>() {
override fun onProgressUpdate(vararg values: Int?) {
super.onProgressUpdate(*values)
//WANT TO WRITE TEXT IN TEXT VIEW BUT HOW TO GET VIEW HERE
listener.onpreogressupdate(...)
}  
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
btnStart.setOnClickListener {
val tvCounter=findViewById<TextView>(R.id.tvCounter)
CountTask(object:listener:UpdateListener{

override fun onProgressUpdate(progress:Int){
//TODO update here
}

}).execute(5)
}
}