在ASyncTask中更新TextView

Question

经过多年拖网试图找到一个可以理解的解决方案，我放弃了我的问题，并来到这里看看你是否可以提供帮助。

我的目标：更新一个TextView从1到99999每秒计数而不挂主线程。

package com.myapp.counter; 

import android.os.AsyncTask; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.TextView; 
import android.widget.Toast; 

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     myBackgroundThread myThread = new myBackgroundThread(); 

     myThread.execute(); 
    } 


    private class myBackgroundThread extends AsyncTask<Void,Integer,Void> 
    { 


     int maxTimer = 99999; 
     int i = 0; 

     //Assign the textView in MainActivity to a variable myCounter. 
     TextView myCounter = (TextView)findViewById(R.id.idCounter); 

     @Override 
     protected void onPreExecute() { 
     } 

     @Override 
     protected Void doInBackground(Void... params) { 

    // Toast.makeText(getApplicationContext(),"InBackground",Toast.LENGTH_SHORT).show(); 
      //Tried Toasting a message upon this starting but just threw an error 
      //Guess because i tried to add a UI component in a background task. 


      for(int i = 0; i < maxTimer; i++) 
      { 

       publishProgress(i); 


      } 

      return null; 

     } 

     //onProgressUpdate is never firing from publishProgress... 
     protected void onProgressUpdate(Integer i) { 


      Toast.makeText(getApplicationContext(),i,Toast.LENGTH_SHORT).show(); 
      //Updatet he counter from 000 to 1,2,3,4 etc. 
      myCounter.setText(i); 

     } 

     protected void onPostExecute(Void result) 
     { 

     } 

    } 


    public void startTimer(View view) 
    { 


     TextView myText = (TextView)findViewById(R.id.textView); 

     // Toast.makeText(this,"Started...", Toast.LENGTH_SHORT).show(); 

    } 


    public void stopTimer(View view) { 


     Toast.makeText(this, "Stopped...", Toast.LENGTH_SHORT).show(); 


    } 

} 

我似乎无法看到为什么publishProgress不会火，我想从按下按钮执行的AsyncTask。

我有3个元素2个按钮startTimer和stopTimer和1个textview在后台更新。

非常感谢所有。

Answer 1

泰这样的事情：

protected class InitTask extends AsyncTask<Context, Integer, String> { 

     // -- run intensive processes here 
     // -- notice that the datatype of the first param in the class definition matches the param passed to this 
     // method 
     // -- and that the datatype of the last param in the class definition matches the return type of this method 
     @Override 
     protected String doInBackground(Context... params) { 
      // -- on every iteration 
      // -- runs a while loop that causes the thread to sleep for 50 milliseconds 
      // -- publishes the progress - calls the onProgressUpdate handler defined below 
      // -- and increments the counter variable i by one 
      int i = 0; 
      while (i <= 50) { 
       try { 
        Thread.sleep(50); 
        publishProgress(i); 
        i++; 
       } 
       catch (Exception e) { 
        Log.i("makemachine", e.getMessage()); 
       } 
      } 
      return "COMPLETE!"; 
     } 

     // -- gets called just before thread begins 
     @Override 
     protected void onPreExecute() { 
      Log.i("makemachine", "onPreExecute()"); 
      super.onPreExecute(); 
     } 

     // -- called from the publish progress 
     // -- notice that the datatype of the second param gets passed to this method 
     @Override 
     protected void onProgressUpdate(Integer... values) { 
      super.onProgressUpdate(values); 
      Log.i("makemachine", "onProgressUpdate(): " + String.valueOf(values[0])); 
      _percentField.setText((values[0] * 2) + "%"); 
      _percentField.setTextSize(values[0]); 
     } 

     // -- called if the cancel button is pressed 
     @Override 
     protected void onCancelled() { 
      super.onCancelled(); 
      Log.i("makemachine", "onCancelled()"); 
      _percentField.setText("Cancelled!"); 
      _percentField.setTextColor(0xFFFF0000); 
     } 

     // -- called as soon as doInBackground method completes 
     // -- notice that the third param gets passed to this method 
     @Override 
     protected void onPostExecute(String result) { 
      super.onPostExecute(result); 
      Log.i("makemachine", "onPostExecute(): " + result); 
      _percentField.setText(result); 
      _percentField.setTextColor(0xFF69adea); 
      _cancelButton.setVisibility(View.INVISIBLE); 
     } 
    } 
}