AsyncTask used to show progress bar

[Monica Marcus]

I wrote a program to show a progress bar using the AsyncTask class. I can see in the Log window the progress in increments of 5, but the progress bar does not show anything. The method showProgress() is activated by a button. Here is the MainActivity class:

package com.example.asynktaskexample_1;

import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.app.Activity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;

public class MainActivity extends Activity {
	ProgressBar prgs;
	ProgressTask task;
	Button showProgressBtn;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		prgs  = (ProgressBar) findViewById(R.id.progress);
		showProgressBtn = (Button) findViewById(R.id.btn);
		showProgressBtn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				showProgress();
			}
		});

	}

	private class ProgressTask extends AsyncTask<Integer,Integer,Void>{
		
		protected void onPreExecute() {
			prgs.setMax(100); // set maximum progress to 100.
			}
		protected void onCancelled() {
			prgs.setMax(0); // stop the progress
			}
		protected Void doInBackground(Integer... params) {
			int start=params[0];
			for(int i=start;i<=100;i+=5){
			try {
			boolean cancelled=isCancelled();
			if(!cancelled){
			publishProgress(i);
			Log.v("Progress","increment " + i);
			onProgressUpdate(i);
			SystemClock.sleep(1000);
			}
			} catch (Exception e) {
			Log.e("Error", e.toString());
			}
			}
			return null;
			}
		protected void onProgressUpdate(Integer... values) {

			// increment progress bar by progress value
				setProgress(10);
			}
		protected void onPostExecute(Void result) {
			// async task finished
			Log.v("Progress", "Finished");
			}

	}
	
	public void showProgress() {
		task = new ProgressTask();
		// start progress bar with initial progress 10
		///////////////////task.execute(10,10,null);
		task.execute(10);
		
	}

}

And here's the layout file:

<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <Button
		android:id="@+id/btn"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content"
		android:text="@string/btn_show_progress"
		android:onClick="showProgress" >
    </Button>
	<ProgressBar
		android:layout_width="fill_parent"
		android:layout_height="wrap_content"
		android:id="@+id/progress"
		android:max="100"
		style="?android:attr/progressBarStyleHorizontal">
	</ProgressBar>
	<Button
		android:id="@+id/btnCancel"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content"
		android:text="@string/btn_cancel" 
		android:onClick="onCancelled">
	</Button>
</LinearLayout>

What is wrong? What is missing? (The Cancel button does not work either, but this is not my main concern now.) I want to see the progress bar animated. Thank you in advance for help! I really need it!

[Swastik Dey]

I haven't tested your code, but look at the documentation of setProgress method. It says Sets the progress for the progress bars in the title.. I guess you need to call setProgess method of ProgressBar class for your own progress bar declared in the xml file.

http://developer.android.com/reference/android/app/Activity.html#setProgress(int)

[Swastik Dey]

protected void onProgressUpdate(Integer... values) {

			// increment progress bar by progress value
				setProgress(10);
				
				prgs.setProgress(prgs.getProgress()+10);
			}

[Monica Marcus]

Hi Swastik, thank you for this idea. It almost works, using your suggestions. The only problem is that the bar does not fill up 100%. But I used your suggestion to pay attention to the setProgress function and I got it work!!!

Here's my program now:

package com.example.asynktaskexample_1;

import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.app.Activity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;

public class MainActivity extends Activity {
	ProgressBar prgs;
	ProgressTask task = new ProgressTask();
	Button showProgressBtn;
	Button stopProgressBtn;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		prgs  = (ProgressBar) findViewById(R.id.progress);
		showProgressBtn = (Button) findViewById(R.id.btn);
		showProgressBtn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				showProgress();
			}
		});
		stopProgressBtn = (Button) findViewById(R.id.btnCancel);
		stopProgressBtn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				stopProgress();
			}
		});

	}

	private class ProgressTask extends AsyncTask<Integer,Integer,Void>{
		
		protected void onPreExecute() {
			super.onPreExecute(); ///////???????
			prgs.setMax(100); // set maximum progress to 100.
			
			}
		protected void onCancelled() {
			prgs.setMax(0); // stop the progress
			Log.v("Progress","Cancelled");
			}
		protected Void doInBackground(Integer... params) {
			int start=params[0];
			for(int i=start;i<=100;i+=5){
			try {
			boolean cancelled=isCancelled();
			if(!cancelled){
			///////////////////////////publishProgress(i); ///
			prgs.setProgress(i);
			Log.v("Progress","increment " + i);
			///////////////////////////onProgressUpdate(i); ///
			SystemClock.sleep(1000);
			}
			} catch (Exception e) {
			Log.e("Error", e.toString());
			}
			}
			return null;
			}
		protected void onProgressUpdate(Integer... values) {

			// increment progress bar by progress value
			    //////////////////////setProgress(10);
				//////////////////////prgs.setProgress(prgs.getProgress() + 5); // the bar does not fill 100%
				prgs.setProgress(5);
				Log.v("Progress","Once");
			}
		protected void onPostExecute(Void result) {
			// async task finished
			Log.v("Progress", "Finished");
			}

	}
	
	public void showProgress() {
		////////////////////task = new ProgressTask();
		// start progress bar with initial progress 10
		///////////////////task.execute(10,5,null);
		task.execute(10);
		
	}

	public void stopProgress() {
	task.cancel(true);	
	}

}

[Swastik Dey]

Hi monica,

I tried with your last code, and for its me its filling the complete bar.

[Monica Marcus]

Yes, it does. That's what I meant to say. I just did not use exactly your code modification, but I got the idea from your code.

[Swastik Dey]

I did that in a hurry, any ways it's great that it worked.

[Marco Di iorio]

To show increment near progress bar and not in logcat?
Thanks