AsyncTask in Android(2)

activity_main.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent" >

    <TextView

        android:id="@+id/textView1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentTop="true"

        android:layout_centerHorizontal="true"

        android:padding="@dimen/padding_medium"

        android:text="@string/async_task"

        tools:context=".AsyncTaskActivity" />

    <ProgressBar

        android:id="@+id/progress"

        style="?android:attr/progressBarStyleHorizontal"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_below="@+id/textView1"

        android:layout_marginTop="34dp" />

    <Button

        android:id="@+id/btn_start"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@+id/progress"

        android:layout_centerHorizontal="true"

        android:layout_marginTop="40dp"

        android:minWidth="120dp"

        android:text="@string/start_btn" />

    <TextView

        android:id="@+id/txt_percentage"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentLeft="true"

        android:layout_below="@+id/progress"

        android:text="downloading  0%"

        android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>

MainActivity.java:

package com.async.ram;

import android.os.AsyncTask;

import android.os.Bundle;

import android.os.SystemClock;

import android.app.Activity;

import android.view.View;

import android.widget.Button;

import android.widget.ProgressBar;

import android.widget.TextView;

import android.widget.Toast;

public class AsyncTaskActivity extends Activity {

Button btn_start;

ProgressBar progressBar;

TextView txt_percentage;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_async_task);

btn_start = (Button) findViewById(R.id.btn_start);

progressBar = (ProgressBar) findViewById(R.id.progress);

txt_percentage = (TextView) findViewById(R.id.txt_percentage);

btn_start.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

btn_start.setEnabled(false);

new ShowDialogAsyncTask().execute();

}

});

}

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

int progress_status;

@Override

protected void onPreExecute() {

// update the UI immediately after the task is executed

super.onPreExecute();

progress_status = 0;

txt_percentage.setText("downloading 0%");

}

@Override

protected Void doInBackground(Void... params) {

while (progress_status < 100) {

progress_status += 2;

publishProgress(progress_status);

SystemClock.sleep(300);

}

return null;

}

@Override

protected void onProgressUpdate(Integer... values) {

super.onProgressUpdate(values);

progressBar.setProgress(values[0]);

txt_percentage.setText("downloading " + values[0] + "%");

}

@Override

protected void onPostExecute(Void result) {

super.onPostExecute(result);

txt_percentage.setText("download complete");

btn_start.setEnabled(true);

}

}

}