Progress Bar while media player is preparing-Collection of common programming errors

11 years ago

admin

5 minutes

I am trying to figure out how to have a progress bar that says “Loading. Please Wait…” while my media player prepares a streaming file. What occurs now is that it displays after the song is prepared. how can i fix this?

        mediaPlayerLoadingBar =ProgressDialog.show(PlaylistActivity.this, "", "Loading. Please wait...", true);         
                    /*dubstep stream*/
                    try {
                        dubstepMediaPlayer.setDataSource(dubstepPlaylistString[0]);
                        dubstepMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
                        dubstepMediaPlayer.prepare();

                    } catch (IllegalArgumentException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (SecurityException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (IllegalStateException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }


                    dubstepMediaPlayer.start();
                    if(dubstepMediaPlayer.isPlaying()){
                        mediaPlayerLoadingBar.dismiss();
                    }`

EDIT: This is the code I have now:

`switch(pSelection){ case 1:

                    new AsyncTask(){

                    @Override
                    protected void onPreExecute(){
                        mediaPlayerLoadingBar =ProgressDialog.show(PlaylistActivity.this, "", "Loading. Please wait...", true);
                        try {
                            dubstepMediaPlayer.setDataSource(dubstepPlaylistString[0]);
                        } catch (IllegalArgumentException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        } catch (IllegalStateException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                        dubstepMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
                    }

                    @Override
                    protected Void doInBackground(Void... params) {
                        // TODO Auto-generated method stub
                        //mediaPlayerLoadingBar =ProgressDialog.show(PlaylistActivity.this, "", "Loading. Please wait...", true);
                        return null;
                    }

                    protected void onPostExecute(Void result){
                        //mediaPlayerLoadingBar =ProgressDialog.show(PlaylistActivity.this, "", "Loading. Please wait...", true)
                            dubstepMediaPlayer.prepareAsync();
                        dubstepMediaPlayer.start();
                        mediaPlayerLoadingBar.dismiss();

                }

                }.execute();`

The issue lies in that you are not doing anything asynchronously here, and you should be. You should use an AsyncTask to do your work.

Take a look at ‘the 4 steps’, as detailed here:

The 4 steps

When an asynchronous task is executed, the task goes through 4 steps:
1. onPreExecute(), invoked on the UI thread immediately after the task is executed. This step is normally used to setup the task, for instance by showing a progress bar in the user interface.
2. doInBackground(Params…), invoked on the background thread immediately after onPreExecute() finishes executing. This step is used to perform background computation that can take a long time. The parameters of the asynchronous task are passed to this step. The result of the computation must be returned by this step and will be passed back to the last step. This step can also use publishProgress(Progress…) to publish one or more units of progress. These values are published on the UI thread, in the onProgressUpdate(Progress…) step.
3. onProgressUpdate(Progress…), invoked on the UI thread after a call to publishProgress(Progress…). The timing of the execution is undefined. This method is used to display any form of progress in the user interface while the background computation is still executing. For instance, it can be used to animate a progress bar or show logs in a text field.
4. onPostExecute(Result), invoked on the UI thread after the background computation finishes. The result of the background computation is passed to this step as a parameter.
EDIT:

You can create an anonymous inner class to do your bidding, which may be similar to how you are creating your onClick handler. In your onClick do something like this:
```
//pseudo-code...
onClick(View v, ...) {
    new AsyncTask() {
        protected void onPreExecute() {
            // do pre execute stuff...
        }

        protected Generic3 doInBackground(Generic1... params) {
            // do background stuff...
        }

        protected void onPostExecute(Generic3 result) {
            // do post execute stuff...
        }
    }.execute();
}
```
Don’t forget to keep an eye on your generics here!

Here is the activity class.Here i am showing the way only.

package com.android.mediaactivity;

import android.app.Activity;
import android.os.Bundle;
import android.widget.LinearLayout;
import android.widget.ProgressBar;

    public class MediaActivity extends Activity 
    {
        public LinearLayout mainLayout;
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) 
        {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            mainLayout=(LinearLayout)findViewById(R.id.mainlinear);
            MediaPlayer media=new MediaPlayer(this);
            media.startPlayer();
        }
    }

Here is mediaplayerclass.

package com.android.mediaactivity;

import java.io.IOException;

import android.media.MediaPlayer.OnPreparedListener;

public class MediaPlayer implements OnPreparedListener {    MediaActivity mediaActivity;    android.media.MediaPlayer mediaPlayer;  public MediaPlayer(MediaActivity mediaActivity)     {       this.mediaActivity=mediaActivity;   }   public void startPlayer()   {       mediaPlayer=new android.media.MediaPlayer();
           mediaPlayer.setOnPreparedListener(this);         mediaPlayer.reset();        try {           mediaPlayer.setDataSource("");          mediaPlayer.prepareAsync();             toggleProgress(true);       } catch (IllegalArgumentException e) {          // TODO Auto-generated catch block          e.printStackTrace();        } catch (IllegalStateException e) {             // TODO Auto-generated catch block          e.printStackTrace();        } catch (IOException e) {           // TODO Auto-generated catch block          e.printStackTrace();        }   }   public void onPrepared(android.media.MediaPlayer mp)    {       toggleProgress(false);      mediaPlayer.start();    }
    public void toggleProgress(final boolean show)
    {
        mediaActivity.runOnUiThread(new Runnable() 
        {
            public void run() 
            {
                if(show)
                        mediaActivity.mainLayout.setVisibility(mediaActivity.mainLayout.VISIBLE);
                else
                        mediaActivity.mainLayout.setVisibility(mediaActivity.mainLayout.INVISIBLE);             }       });
    }

}

And here is the main.xml

When you say prepare on the underlying mediaplayer object, internally it really does some preparation like – setting up the extractor for the file, setting up the audio decoder to decode the encoded audio file and setting up the audio sink to play the raw audio data that was decoded from the decoder. Now all this will take time, it is not instantaneous.

So in your original code, you check if the mediaplayer isPlaying and then dismiss it but the problem is at that point of time the mediaplayer is not playing the audio yet and thus your dismiss is never called so it always visible.

What you need to do is implement the listener MediaPlayer.OnPreparedListener and when the method onPrepared is called in your application call the dismiss mediaPlayerLoadingBar.dismiss(); in that method.