Android UI How to - Update the UI from a separate thread with AsyncTask

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The following code shows how to Update the UI from a separate thread with AsyncTask.

Example

Main layout xml file

<?xml version="1.0" encoding="utf-8"?>
  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello" />

<Button
    android:id="@+id/btnStartCounter"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Start"
    android:onClick="startCounter" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="TextView" />

</LinearLayout>

Main Activity Java code

package com.java2s.myapplication3.app;
/*  w w  w.  ja v  a 2 s  .  co m*/

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity {
    TextView txtView1;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(android.R.layout.main);

        txtView1 = (TextView) findViewById(android.R.id.textView1);
    }

    private class DoCountingTask extends AsyncTask<Void, Integer, Void> {
        protected Void doInBackground(Void... params) {
            for (int i = 0; i < 1000; i++) {
                publishProgress(i);
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    Log.d("Threading", e.getLocalizedMessage());
                }
            }
            return null;
        }

        protected void onProgressUpdate(Integer... progress) {
            txtView1.setText(progress[0].toString());
            Log.d("Threading", "updating...");
        }
    }

    public void startCounter(View view) {
        new DoCountingTask().execute();
    }

}

}

The preceding code will update the UI safely from another thread.

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