In this tutorial i am going to discuss building a simple audio player with basic controls like play, pause, forward, backward, next, previous, playlist and seekbar. This app basically will read all audio files(.mp3) from sdcard and plays selected song. For this tutorial i am referencing MediaPlayer and go through it if you need any documentation about usage.

Android MediaPlayer Class

Android SDK is providing MediaPlayer Class to access android in built mediaplayer services like playing audio, video etc., In this tutorial i am using following functions of this class to control audio player.

MediaPlayer mp = new MediaPlayer();

// Set data source -
setDataSource("/sdcard/path_to_song");

// Play audio
mp.start();

// Pause audio
mp.pause();

// Reset mediaplayer
mp.reset();

// Get song length duration - in milliseconds
mp.getDuration();

// Get current duration - in milliseconds
mp.getCurrentDuration();

// Move song to particular second - used for Forward or Backward
mp.seekTo(positon); // position in milliseconds

// Check if song is playing or not
mp.isPlaying(); // returns true or false

1. Designing the Audio Player Layout

Design your audio player using some graphic designing softwares like photoshop. I used photoshop to design this app layout. If you are not aware of designing just download the required images from the internet. Following is a screenshot of the audio player which we are going to build in this tutorial. (You can find this layout PSD in the download code)

2. Preparing Required Icons and Images

Once you are done with your app layout design, prepare the required icons and background images for the audio player application. Prepare your icons in different states like default, focused and pressed and place them all in your drawable folder.

3. Writing XML layouts for ICON states (default/hover/pressed)

After saving all the icons with different states, we need to write xml drawable for each icon. Following is a sample for play button. Save this file under drawable folder.

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/img_btn_play_pressed"
        android:state_focused="true"
        android:state_pressed="true" />
    <item android:drawable="@drawable/img_btn_play_pressed"
        android:state_focused="false"
        android:state_pressed="true" />
    <item android:drawable="@drawable/img_btn_play_pressed"
        	android:state_focused="true" />
    <item android:drawable="@drawable/img_btn_play"
        android:state_focused="false"
        android:state_pressed="false" />
</selector>

Note: You need to write xml drawable for each icon you used for the player (like btn_pause.xml, btn_next.xml etc,.)

4. Writing XML design for SeekBar

In this tutorial i used customized SeekBar to show song progress. You can design the style of default SeekBar using xml styles. In your drawable folder create to xml files and type the following code.

Changing SeekBar background:

<?xml version="1.0" encoding="utf-8"?>
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <clip>
        <bitmap xmlns:android="http://schemas.android.com/apk/res/android"
            android:src="@drawable/img_seekbar_progress_blue"
            android:tileMode="repeat"
            android:antialias="true"
            android:dither="false"
            android:filter="false"
            android:gravity="left"
        />
        </clip>
    </item>
</layer-list>

Changing SeekBar Progress:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@android:id/background"
        android:drawable="@drawable/img_seekbar_bg"
        android:dither="true">
    </item>
    <item android:id="@android:id/secondaryProgress">
        <clip>
            <shape>
                <gradient
                    android:startColor="#80028ac8"
                    android:centerColor="#80127fb1"
                    android:centerY="0.75"
                    android:endColor="#a004638f"
                    android:angle="270"
                />
            </shape>
        </clip>
    </item>
    <item
        android:id="@android:id/progress"
        android:drawable="@drawable/seekbar_progress_bg"
    />
</layer-list>

Actual seekbar which uses above xml files:

<SeekBar
        	android:id="@+id/songProgressBar"
	         android:layout_width="fill_parent"
	         android:layout_height="wrap_content"
	         android:layout_marginRight="20dp"
	         android:layout_marginLeft="20dp"
	         android:layout_marginBottom="20dp"
	    	 android:layout_above="@id/player_footer_bg"
	    	 android:thumb="@drawable/seek_handler"
	    	 android:progressDrawable="@drawable/seekbar_progress"
	    	 android:paddingLeft="6dp"
	    	 android:paddingRight="6dp"/>

5. Writing XML for Player Layout

So far we created separate xml layout for all the icons, seekbar. Now we need to combine everything into single layout. Create a new file called player.xml under layout folder and paste the following code.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/player_background"> 

    <!-- Player Header -->
    <LinearLayout
        android:id="@+id/player_header_bg"
        android:layout_width="fill_parent"
        android:layout_height="60dip"
        android:background="@layout/bg_player_header"
        android:layout_alignParentTop="true"
        android:paddingLeft="5dp"
        android:paddingRight="5dp">

        <!-- Song Title -->
        <TextView
            android:id="@+id/songTitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:textColor="#04b3d2"
            android:textSize="16dp"
            android:paddingLeft="10dp"
            android:textStyle="bold"
            android:text="The Good, The Bad And The Ugly"
            android:layout_marginTop="10dp"/>

        <!-- Playlist button -->
        <ImageButton
            android:id="@+id/btnPlaylist"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:src="@drawable/btn_playlist"
            android:background="@null"/>
    </LinearLayout>

    <!-- Song Thumbnail Image -->
    <LinearLayout
        android:id="@+id/songThumbnail"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingTop="10dp"
        android:paddingBottom="10dp"
        android:gravity="center"
        android:layout_below="@id/player_header_bg">
    	<ImageView android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/adele"/>
    </LinearLayout>

    <!-- Player Footer -->
    <LinearLayout
        android:id="@+id/player_footer_bg"
        android:layout_width="fill_parent"
        android:layout_height="100dp"
        android:layout_alignParentBottom="true"
        android:background="@layout/bg_player_footer"
        android:gravity="center">

        <!-- Player Buttons -->
        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:gravity="center_vertical"
            android:background="@layout/rounded_corner"
            android:paddingLeft="10dp"
            android:paddingRight="10dp">
            <!-- Previous Button -->
            <ImageButton
                android:id="@+id/btnPrevious"
                android:src="@drawable/btn_previous"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@null"/>
            <!-- Backward Button -->
            <ImageButton
                android:id="@+id/btnBackward"
                android:src="@drawable/btn_backward"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@null"/>
            <!-- Play Button -->
            <ImageButton
                android:id="@+id/btnPlay"
                android:src="@drawable/btn_play"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@null"/>
            <!-- Forward Button -->
            <ImageButton
                android:id="@+id/btnForward"
                android:src="@drawable/btn_forward"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@null"/>
            <!-- Next Button -->
            <ImageButton
                android:id="@+id/btnNext"
                android:src="@drawable/btn_next"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@null"/>
        </LinearLayout>
    </LinearLayout>

    <!-- Progress Bar/Seek bar -->
    <SeekBar
        	android:id="@+id/songProgressBar"
	         android:layout_width="fill_parent"
	         android:layout_height="wrap_content"
	         android:layout_marginRight="20dp"
	         android:layout_marginLeft="20dp"
	         android:layout_marginBottom="20dp"
	    	 android:layout_above="@id/player_footer_bg"
	    	 android:thumb="@drawable/seek_handler"
	    	 android:progressDrawable="@drawable/seekbar_progress"
	    	 android:paddingLeft="6dp"
	    	 android:paddingRight="6dp"/>

    <!-- Timer Display -->
    <LinearLayout
        android:id="@+id/timerDisplay"
        android:layout_above="@id/songProgressBar"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginRight="20dp"
        android:layout_marginLeft="20dp"
        android:layout_marginBottom="10dp">
        <!-- Current Duration Label -->
        <TextView
            android:id="@+id/songCurrentDurationLabel"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="left"
            android:textColor="#eeeeee"
            android:textStyle="bold"/>
        <!-- Total Duration Label -->
        <TextView
            android:id="@+id/songTotalDurationLabel"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="right"
            android:textColor="#04cbde"
            android:textStyle="bold"/>
    </LinearLayout>

    <!-- Repeat / Shuffle buttons -->
    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/timerDisplay"
        android:gravity="center">
        <!-- Repeat Button -->
        <ImageButton
            android:id="@+id/btnRepeat"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/btn_repeat"
            android:layout_marginRight="5dp"
            android:background="@null"/>

        <!-- Shuffle Button -->
         <ImageButton
            android:id="@+id/btnShuffle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/btn_shuffle"
            android:layout_marginLeft="5dp"
            android:background="@null"/>
    </LinearLayout>
</RelativeLayout>

The above xml will give following output layout.

6. Writing XML for PlayList ListView

Playlist is displayed using a listview. If you are not aware of listview go through this Android ListView Tutorial and get an idea of listview layout.

⇒ Create an xml file under drawable folder and name it as list_selector.xml and type following code. This xml is used for gradient background for list item.

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Selector style for listrow -->
<item
 android:state_selected="false"
    android:state_pressed="false"
    android:drawable="@drawable/gradient_bg" />
<item android:state_pressed="true"
    android:drawable="@drawable/gradient_bg_hover" />
<item android:state_selected="true"
 android:state_pressed="false"
    android:drawable="@drawable/gradient_bg_hover" />
</selector>

⇒ Create a new xml file under layout layout folder and name it as playlist.xml and type the following code. This xml file is for listview.

<?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">

    <ListView
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:divider="#242424"
        android:dividerHeight="1dp"
        android:listSelector="@drawable/list_selector" />

</LinearLayout>

⇒ Also create a new xml file under layout folder for single List Item. Name file as playlist_item.xml and type following code. This xml file is for single list item which holds song title.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    android:background="@drawable/list_selector"
    android:padding="5dp">
    <TextView
        android:id="@+id/songTitle"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="16dp"
        android:padding="10dp"
        android:color="#f3f3f3"/>
</LinearLayout>

By using above layout we can achieve following list view by loading data into it.

7. Writing Class for reading MP3 files from SDcard

So far we are done with static layouts for the player. Now the actual code starts.
Create a new class file and name it as SongsManager.java. This class will read all the files from device sdcard and filters the files which are having .mp3 extension.

package com.androidhive.musicplayer;

import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.HashMap;

public class SongsManager {
	// SDCard Path
	final String MEDIA_PATH = new String("/sdcard/");
	private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

	// Constructor
	public SongsManager(){

	}

	/**
	 * Function to read all mp3 files from sdcard
	 * and store the details in ArrayList
	 * */
	public ArrayList<HashMap<String, String>> getPlayList(){
		File home = new File(MEDIA_PATH);

		if (home.listFiles(new FileExtensionFilter()).length > 0) {
			for (File file : home.listFiles(new FileExtensionFilter())) {
				HashMap<String, String> song = new HashMap<String, String>();
				song.put("songTitle", file.getName().substring(0, (file.getName().length() - 4)));
				song.put("songPath", file.getPath());

				// Adding each song to SongList
				songsList.add(song);
			}
		}
		// return songs list array
		return songsList;
	}

	/**
	 * Class to filter files which are having .mp3 extension
	 * */
	class FileExtensionFilter implements FilenameFilter {
		public boolean accept(File dir, String name) {
			return (name.endsWith(".mp3") || name.endsWith(".MP3"));
		}
	}
}

8. Writing Class for PlayList ListView

Create a new Activity class for playlist listview. Name the file as PlayListActivity.java This class will display list of songs in list layout by using SongsManager.java class

package com.androidhive.musicplayer;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class PlayListActivity extends ListActivity {
	// Songs list
	public ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.playlist);

		ArrayList<HashMap<String, String>> songsListData = new ArrayList<HashMap<String, String>>();

		SongsManager plm = new SongsManager();
		// get all songs from sdcard
		this.songsList = plm.getPlayList();

		// looping through playlist
		for (int i = 0; i < songsList.size(); i++) {
			// creating new HashMap
			HashMap<String, String> song = songsList.get(i);

			// adding HashList to ArrayList
			songsListData.add(song);
		}

		// Adding menuItems to ListView
		ListAdapter adapter = new SimpleAdapter(this, songsListData,
				R.layout.playlist_item, new String[] { "songTitle" }, new int[] {
						R.id.songTitle });

		setListAdapter(adapter);

		// selecting single ListView item
		ListView lv = getListView();
		// listening to single listitem click
		lv.setOnItemClickListener(new OnItemClickListener() {

			@Override
			public void onItemClick(AdapterView<?> parent, View view,
					int position, long id) {
				// getting listitem index
				int songIndex = position;

				// Starting new intent
				Intent in = new Intent(getApplicationContext(),
						AndroidBuildingMusicPlayerActivity.class);
				// Sending songIndex to PlayerActivity
				in.putExtra("songIndex", songIndex);
				setResult(100, in);
				// Closing PlayListView
				finish();
			}
		});
	}
}

9. Helper Class functions

Create a new class called Utilities.java for handling extra work like converting time to progress percentage and vice-versa. Also it has function to convert millisecond to a timer string which will displayed on the seekbar of the player.

package com.androidhive.musicplayer;

public class Utilities {

	/**
	 * Function to convert milliseconds time to
	 * Timer Format
	 * Hours:Minutes:Seconds
	 * */
	public String milliSecondsToTimer(long milliseconds){
		String finalTimerString = "";
		String secondsString = "";

		// Convert total duration into time
		   int hours = (int)( milliseconds / (1000*60*60));
		   int minutes = (int)(milliseconds % (1000*60*60)) / (1000*60);
		   int seconds = (int) ((milliseconds % (1000*60*60)) % (1000*60) / 1000);
		   // Add hours if there
		   if(hours > 0){
			   finalTimerString = hours + ":";
		   }

		   // Prepending 0 to seconds if it is one digit
		   if(seconds < 10){
			   secondsString = "0" + seconds;
		   }else{
			   secondsString = "" + seconds;}

		   finalTimerString = finalTimerString + minutes + ":" + secondsString;

		// return timer string
		return finalTimerString;
	}

	/**
	 * Function to get Progress percentage
	 * @param currentDuration
	 * @param totalDuration
	 * */
	public int getProgressPercentage(long currentDuration, long totalDuration){
		Double percentage = (double) 0;

		long currentSeconds = (int) (currentDuration / 1000);
		long totalSeconds = (int) (totalDuration / 1000);

		// calculating percentage
		percentage =(((double)currentSeconds)/totalSeconds)*100;

		// return percentage
		return percentage.intValue();
	}

	/**
	 * Function to change progress to timer
	 * @param progress -
	 * @param totalDuration
	 * returns current duration in milliseconds
	 * */
	public int progressToTimer(int progress, int totalDuration) {
		int currentDuration = 0;
		totalDuration = (int) (totalDuration / 1000);
		currentDuration = (int) ((((double)progress) / 100) * totalDuration);

		// return current duration in milliseconds
		return currentDuration * 1000;
	}
}

7. Writing Classes needed for Audio Player

Open your main activity class which deals with main player interface and make the class implements from OnCompletionListener, SeekBar.OnSeekBarChangeListener.
In this case my main activity name is AndroidBuildingMusicPlayerActivity.

public class AndroidBuildingMusicPlayerActivity extends Activity
       implements OnCompletionListener, SeekBar.OnSeekBarChangeListener {

Now declare all variable needed for this audio player class.

public class AndroidBuildingMusicPlayerActivity extends Activity
       implements OnCompletionListener, SeekBar.OnSeekBarChangeListener {

	private ImageButton btnPlay;
	private ImageButton btnForward;
	private ImageButton btnBackward;
	private ImageButton btnNext;
	private ImageButton btnPrevious;
	private ImageButton btnPlaylist;
	private ImageButton btnRepeat;
	private ImageButton btnShuffle;
	private SeekBar songProgressBar;
	private TextView songTitleLabel;
	private TextView songCurrentDurationLabel;
	private TextView songTotalDurationLabel;
	// Media Player
	private  MediaPlayer mp;
	// Handler to update UI timer, progress bar etc,.
	private Handler mHandler = new Handler();;
	private SongsManager songManager;
	private Utilities utils;
	private int seekForwardTime = 5000; // 5000 milliseconds
	private int seekBackwardTime = 5000; // 5000 milliseconds
	private int currentSongIndex = 0;
	private boolean isShuffle = false;
	private boolean isRepeat = false;
	private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

Now reference all buttons, images from xml layout to class.

// All player buttons
		btnPlay = (ImageButton) findViewById(R.id.btnPlay);
		btnForward = (ImageButton) findViewById(R.id.btnForward);
		btnBackward = (ImageButton) findViewById(R.id.btnBackward);
		btnNext = (ImageButton) findViewById(R.id.btnNext);
		btnPrevious = (ImageButton) findViewById(R.id.btnPrevious);
		btnPlaylist = (ImageButton) findViewById(R.id.btnPlaylist);
		btnRepeat = (ImageButton) findViewById(R.id.btnRepeat);
		btnShuffle = (ImageButton) findViewById(R.id.btnShuffle);
		songProgressBar = (SeekBar) findViewById(R.id.songProgressBar);
		songTitleLabel = (TextView) findViewById(R.id.songTitle);
		songCurrentDurationLabel = (TextView) findViewById(R.id.songCurrentDurationLabel);
		songTotalDurationLabel = (TextView) findViewById(R.id.songTotalDurationLabel);

		// Mediaplayer
		mp = new MediaPlayer();
		songManager = new SongsManager();
		utils = new Utilities();

		// Listeners
		songProgressBar.setOnSeekBarChangeListener(this); // Important
		mp.setOnCompletionListener(this); // Important

		// Getting all songs list
		songsList = songManager.getPlayList();

Launching PlayList

Write click event listener to playlist button. On clicking playlist button we need to launch PlayListAcitivity.java and from listview on selecting a particular song we need get songIndex.

/**
		 * Button Click event for Play list click event
		 * Launches list activity which displays list of songs
		 * */
		btnPlaylist.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				Intent i = new Intent(getApplicationContext(), PlayListActivity.class);
				startActivityForResult(i, 100);
			}
		});

To receive the selected songIndex add following fucntion. (Make sure that you added this function outside of onCreate method)

/**
	 * Receiving song index from playlist view
	 * and play the song
	 * */
	@Override
    protected void onActivityResult(int requestCode,
                                     int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(resultCode == 100){
         	 currentSongIndex = data.getExtras().getInt("songIndex");
         	 // play selected song
             playSong(currentSongIndex);
        }

    }

Playing Song

Add the following function to your class. This function accepts songIndex as param and plays it. Also when start playing a song it switches the play button to pause button state.

/**
	 * Function to play a song
	 * @param songIndex - index of song
	 * */
	public void  playSong(int songIndex){
		// Play song
		try {
        	mp.reset();
			mp.setDataSource(songsList.get(songIndex).get("songPath"));
			mp.prepare();
			mp.start();
			// Displaying Song title
			String songTitle = songsList.get(songIndex).get("songTitle");
        	songTitleLabel.setText(songTitle);

        	// Changing Button Image to pause image
			btnPlay.setImageResource(R.drawable.btn_pause);

			// set Progress bar values
			songProgressBar.setProgress(0);
			songProgressBar.setMax(100);

			// Updating progress bar
			updateProgressBar();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalStateException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

Forward / Backward button click events

Add event listeners to Forward and Backward buttons which forwards or backwards song by specified seconds.

Forward button click event – moves song to specified number of seconds forward

/**
		 * Forward button click event
		 * Forwards song specified seconds
		 * */
		btnForward.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// get current song position
				int currentPosition = mp.getCurrentPosition();
				// check if seekForward time is lesser than song duration
				if(currentPosition + seekForwardTime <= mp.getDuration()){
					// forward song
					mp.seekTo(currentPosition + seekForwardTime);
				}else{
					// forward to end position
					mp.seekTo(mp.getDuration());
				}
			}
		});

Backward button click event – moves song to specified number of seconds backward

/**
		 * Backward button click event
		 * Backward song to specified seconds
		 * */
		btnBackward.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// get current song position
				int currentPosition = mp.getCurrentPosition();
				// check if seekBackward time is greater than 0 sec
				if(currentPosition - seekBackwardTime >= 0){
					// forward song
					mp.seekTo(currentPosition - seekBackwardTime);
				}else{
					// backward to starting position
					mp.seekTo(0);
				}

			}
		});

Next / Back button click events

Add click listeners to next and back buttons.

Next button click event – which plays next song from the playlist if presents else plays first song

/**
		 * Next button click event
		 * Plays next song by taking currentSongIndex + 1
		 * */
		btnNext.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// check if next song is there or not
				if(currentSongIndex < (songsList.size() - 1)){
					playSong(currentSongIndex + 1);
					currentSongIndex = currentSongIndex + 1;
				}else{
					// play first song
					playSong(0);
					currentSongIndex = 0;
				}

			}
		});

Back button click event – which plays previous song if presents or plays last song

/**
		 * Back button click event
		 * Plays previous song by currentSongIndex - 1
		 * */
		btnPrevious.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				if(currentSongIndex > 0){
					playSong(currentSongIndex - 1);
					currentSongIndex = currentSongIndex - 1;
				}else{
					// play last song
					playSong(songsList.size() - 1);
					currentSongIndex = songsList.size() - 1;
				}

			}
		});

Updating SeekBar progress and Timer

To update progress bar timer i implemented a background thread which runs in background using a Handler. If you new to Handler follow this doc. Updating the UI from a Timer

/**
	 * Update timer on seekbar
	 * */
	public void updateProgressBar() {
        mHandler.postDelayed(mUpdateTimeTask, 100);
    }	

	/**
	 * Background Runnable thread
	 * */
	private Runnable mUpdateTimeTask = new Runnable() {
		   public void run() {
			   long totalDuration = mp.getDuration();
			   long currentDuration = mp.getCurrentPosition();

			   // Displaying Total Duration time
			   songTotalDurationLabel.setText(""+utils.milliSecondsToTimer(totalDuration));
			   // Displaying time completed playing
			   songCurrentDurationLabel.setText(""+utils.milliSecondsToTimer(currentDuration));

			   // Updating progress bar
			   int progress = (int)(utils.getProgressPercentage(currentDuration, totalDuration));
			   //Log.d("Progress", ""+progress);
			   songProgressBar.setProgress(progress);

			   // Running this thread after 100 milliseconds
		       mHandler.postDelayed(this, 100);
		   }
		};

	/**
	 *
	 * */
	@Override
	public void onProgressChanged(SeekBar seekBar, int progress, boolean fromTouch) {

	}

	/**
	 * When user starts moving the progress handler
	 * */
	@Override
	public void onStartTrackingTouch(SeekBar seekBar) {
		// remove message Handler from updating progress bar
		mHandler.removeCallbacks(mUpdateTimeTask);
    }

	/**
	 * When user stops moving the progress hanlder
	 * */
	@Override
    public void onStopTrackingTouch(SeekBar seekBar) {
		mHandler.removeCallbacks(mUpdateTimeTask);
		int totalDuration = mp.getDuration();
		int currentPosition = utils.progressToTimer(seekBar.getProgress(), totalDuration);

		// forward or backward to certain seconds
		mp.seekTo(currentPosition);

		// update timer progress again
		updateProgressBar();
    }

Repeat button click event

On clicking repeat button we need to set isRepeat to true and vice-versa. Also we need to change image source of repeat button to focused state.

/**
		 * Button Click event for Repeat button
		 * Enables repeat flag to true
		 * */
		btnRepeat.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				if(isRepeat){
					isRepeat = false;
					Toast.makeText(getApplicationContext(), "Repeat is OFF", Toast.LENGTH_SHORT).show();
					btnRepeat.setImageResource(R.drawable.btn_repeat);
				}else{
					// make repeat to true
					isRepeat = true;
					Toast.makeText(getApplicationContext(), "Repeat is ON", Toast.LENGTH_SHORT).show();
					// make shuffle to false
					isShuffle = false;
					btnRepeat.setImageResource(R.drawable.btn_repeat_focused);
					btnShuffle.setImageResource(R.drawable.btn_shuffle);
				}
			}
		});

Shuffle button click event

On clicking shuffle button we need to set isShuffle to true and vice-versa. Also we need to change image source of shuffle button to focused state.

/**
		 * Button Click event for Shuffle button
		 * Enables shuffle flag to true
		 * */
		btnShuffle.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				if(isShuffle){
					isShuffle = false;
					Toast.makeText(getApplicationContext(), "Shuffle is OFF", Toast.LENGTH_SHORT).show();
					btnShuffle.setImageResource(R.drawable.btn_shuffle);
				}else{
					// make repeat to true
					isShuffle= true;
					Toast.makeText(getApplicationContext(), "Shuffle is ON", Toast.LENGTH_SHORT).show();
					// make shuffle to false
					isRepeat = false;
					btnShuffle.setImageResource(R.drawable.btn_shuffle_focused);
					btnRepeat.setImageResource(R.drawable.btn_repeat);
				}
			}
		});

Implementing song onCompletion Listener

It is important to implement this listener which will notify you once the song is completed playing. In this method we need to play next song automatically depending on repeat and shuffle conditions.

/**
	 * On Song Playing completed
	 * if repeat is ON play same song again
	 * if shuffle is ON play random song
	 * */
	@Override
	public void onCompletion(MediaPlayer arg0) {

		// check for repeat is ON or OFF
		if(isRepeat){
			// repeat is on play same song again
			playSong(currentSongIndex);
		} else if(isShuffle){
			// shuffle is on - play a random song
			Random rand = new Random();
			currentSongIndex = rand.nextInt((songsList.size() - 1) - 0 + 1) + 0;
			playSong(currentSongIndex);
		} else{
			// no repeat or shuffle ON - play next song
			if(currentSongIndex < (songsList.size() - 1)){
				playSong(currentSongIndex + 1);
				currentSongIndex = currentSongIndex + 1;
			}else{
				// play first song
				playSong(0);
				currentSongIndex = 0;
			}
		}
	}

Update your AndroidManifest.xml

Update your AndroidManifest.xml to following code. Add android:configChanges=”keyboardHidden|orientation” to your main activity node.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.androidhive.musicplayer"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="8" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".AndroidBuildingMusicPlayerActivity"
            android:label="@string/app_name"
            android:configChanges="keyboardHidden|orientation">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name=".PlayListActivity" />
    </application>

</manifest>
<!-- AndroidBuildingMusicPlayerActivity -->

Final Code

Following is complete code for the AndroidBuildingMusicPlayerActivity.java class.

package com.androidhive.musicplayer;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Random;

import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.ImageButton;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.Toast;

public class AndroidBuildingMusicPlayerActivity extends Activity implements OnCompletionListener, SeekBar.OnSeekBarChangeListener {

	private ImageButton btnPlay;
	private ImageButton btnForward;
	private ImageButton btnBackward;
	private ImageButton btnNext;
	private ImageButton btnPrevious;
	private ImageButton btnPlaylist;
	private ImageButton btnRepeat;
	private ImageButton btnShuffle;
	private SeekBar songProgressBar;
	private TextView songTitleLabel;
	private TextView songCurrentDurationLabel;
	private TextView songTotalDurationLabel;
	// Media Player
	private  MediaPlayer mp;
	// Handler to update UI timer, progress bar etc,.
	private Handler mHandler = new Handler();;
	private SongsManager songManager;
	private Utilities utils;
	private int seekForwardTime = 5000; // 5000 milliseconds
	private int seekBackwardTime = 5000; // 5000 milliseconds
	private int currentSongIndex = 0;
	private boolean isShuffle = false;
	private boolean isRepeat = false;
	private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.player);

		// All player buttons
		btnPlay = (ImageButton) findViewById(R.id.btnPlay);
		btnForward = (ImageButton) findViewById(R.id.btnForward);
		btnBackward = (ImageButton) findViewById(R.id.btnBackward);
		btnNext = (ImageButton) findViewById(R.id.btnNext);
		btnPrevious = (ImageButton) findViewById(R.id.btnPrevious);
		btnPlaylist = (ImageButton) findViewById(R.id.btnPlaylist);
		btnRepeat = (ImageButton) findViewById(R.id.btnRepeat);
		btnShuffle = (ImageButton) findViewById(R.id.btnShuffle);
		songProgressBar = (SeekBar) findViewById(R.id.songProgressBar);
		songTitleLabel = (TextView) findViewById(R.id.songTitle);
		songCurrentDurationLabel = (TextView) findViewById(R.id.songCurrentDurationLabel);
		songTotalDurationLabel = (TextView) findViewById(R.id.songTotalDurationLabel);

		// Mediaplayer
		mp = new MediaPlayer();
		songManager = new SongsManager();
		utils = new Utilities();

		// Listeners
		songProgressBar.setOnSeekBarChangeListener(this); // Important
		mp.setOnCompletionListener(this); // Important

		// Getting all songs list
		songsList = songManager.getPlayList();

		// By default play first song
		playSong(0);

		/**
		 * Play button click event
		 * plays a song and changes button to pause image
		 * pauses a song and changes button to play image
		 * */
		btnPlay.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// check for already playing
				if(mp.isPlaying()){
					if(mp!=null){
						mp.pause();
						// Changing button image to play button
						btnPlay.setImageResource(R.drawable.btn_play);
					}
				}else{
					// Resume song
					if(mp!=null){
						mp.start();
						// Changing button image to pause button
						btnPlay.setImageResource(R.drawable.btn_pause);
					}
				}

			}
		});

		/**
		 * Forward button click event
		 * Forwards song specified seconds
		 * */
		btnForward.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// get current song position
				int currentPosition = mp.getCurrentPosition();
				// check if seekForward time is lesser than song duration
				if(currentPosition + seekForwardTime <= mp.getDuration()){
					// forward song
					mp.seekTo(currentPosition + seekForwardTime);
				}else{
					// forward to end position
					mp.seekTo(mp.getDuration());
				}
			}
		});

		/**
		 * Backward button click event
		 * Backward song to specified seconds
		 * */
		btnBackward.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// get current song position
				int currentPosition = mp.getCurrentPosition();
				// check if seekBackward time is greater than 0 sec
				if(currentPosition - seekBackwardTime >= 0){
					// forward song
					mp.seekTo(currentPosition - seekBackwardTime);
				}else{
					// backward to starting position
					mp.seekTo(0);
				}

			}
		});

		/**
		 * Next button click event
		 * Plays next song by taking currentSongIndex + 1
		 * */
		btnNext.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// check if next song is there or not
				if(currentSongIndex < (songsList.size() - 1)){
					playSong(currentSongIndex + 1);
					currentSongIndex = currentSongIndex + 1;
				}else{
					// play first song
					playSong(0);
					currentSongIndex = 0;
				}

			}
		});

		/**
		 * Back button click event
		 * Plays previous song by currentSongIndex - 1
		 * */
		btnPrevious.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				if(currentSongIndex > 0){
					playSong(currentSongIndex - 1);
					currentSongIndex = currentSongIndex - 1;
				}else{
					// play last song
					playSong(songsList.size() - 1);
					currentSongIndex = songsList.size() - 1;
				}

			}
		});

		/**
		 * Button Click event for Repeat button
		 * Enables repeat flag to true
		 * */
		btnRepeat.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				if(isRepeat){
					isRepeat = false;
					Toast.makeText(getApplicationContext(), "Repeat is OFF", Toast.LENGTH_SHORT).show();
					btnRepeat.setImageResource(R.drawable.btn_repeat);
				}else{
					// make repeat to true
					isRepeat = true;
					Toast.makeText(getApplicationContext(), "Repeat is ON", Toast.LENGTH_SHORT).show();
					// make shuffle to false
					isShuffle = false;
					btnRepeat.setImageResource(R.drawable.btn_repeat_focused);
					btnShuffle.setImageResource(R.drawable.btn_shuffle);
				}
			}
		});

		/**
		 * Button Click event for Shuffle button
		 * Enables shuffle flag to true
		 * */
		btnShuffle.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				if(isShuffle){
					isShuffle = false;
					Toast.makeText(getApplicationContext(), "Shuffle is OFF", Toast.LENGTH_SHORT).show();
					btnShuffle.setImageResource(R.drawable.btn_shuffle);
				}else{
					// make repeat to true
					isShuffle= true;
					Toast.makeText(getApplicationContext(), "Shuffle is ON", Toast.LENGTH_SHORT).show();
					// make shuffle to false
					isRepeat = false;
					btnShuffle.setImageResource(R.drawable.btn_shuffle_focused);
					btnRepeat.setImageResource(R.drawable.btn_repeat);
				}
			}
		});

		/**
		 * Button Click event for Play list click event
		 * Launches list activity which displays list of songs
		 * */
		btnPlaylist.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View arg0) {
				Intent i = new Intent(getApplicationContext(), PlayListActivity.class);
				startActivityForResult(i, 100);
			}
		});

	}

	/**
	 * Receiving song index from playlist view
	 * and play the song
	 * */
	@Override
    protected void onActivityResult(int requestCode,
                                     int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(resultCode == 100){
         	 currentSongIndex = data.getExtras().getInt("songIndex");
         	 // play selected song
             playSong(currentSongIndex);
        }

    }

	/**
	 * Function to play a song
	 * @param songIndex - index of song
	 * */
	public void  playSong(int songIndex){
		// Play song
		try {
        	mp.reset();
			mp.setDataSource(songsList.get(songIndex).get("songPath"));
			mp.prepare();
			mp.start();
			// Displaying Song title
			String songTitle = songsList.get(songIndex).get("songTitle");
        	songTitleLabel.setText(songTitle);

        	// Changing Button Image to pause image
			btnPlay.setImageResource(R.drawable.btn_pause);

			// set Progress bar values
			songProgressBar.setProgress(0);
			songProgressBar.setMax(100);

			// Updating progress bar
			updateProgressBar();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalStateException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	/**
	 * Update timer on seekbar
	 * */
	public void updateProgressBar() {
        mHandler.postDelayed(mUpdateTimeTask, 100);
    }	

	/**
	 * Background Runnable thread
	 * */
	private Runnable mUpdateTimeTask = new Runnable() {
		   public void run() {
			   long totalDuration = mp.getDuration();
			   long currentDuration = mp.getCurrentPosition();

			   // Displaying Total Duration time
			   songTotalDurationLabel.setText(""+utils.milliSecondsToTimer(totalDuration));
			   // Displaying time completed playing
			   songCurrentDurationLabel.setText(""+utils.milliSecondsToTimer(currentDuration));

			   // Updating progress bar
			   int progress = (int)(utils.getProgressPercentage(currentDuration, totalDuration));
			   //Log.d("Progress", ""+progress);
			   songProgressBar.setProgress(progress);

			   // Running this thread after 100 milliseconds
		       mHandler.postDelayed(this, 100);
		   }
		};

	/**
	 *
	 * */
	@Override
	public void onProgressChanged(SeekBar seekBar, int progress, boolean fromTouch) {

	}

	/**
	 * When user starts moving the progress handler
	 * */
	@Override
	public void onStartTrackingTouch(SeekBar seekBar) {
		// remove message Handler from updating progress bar
		mHandler.removeCallbacks(mUpdateTimeTask);
    }

	/**
	 * When user stops moving the progress hanlder
	 * */
	@Override
    public void onStopTrackingTouch(SeekBar seekBar) {
		mHandler.removeCallbacks(mUpdateTimeTask);
		int totalDuration = mp.getDuration();
		int currentPosition = utils.progressToTimer(seekBar.getProgress(), totalDuration);

		// forward or backward to certain seconds
		mp.seekTo(currentPosition);

		// update timer progress again
		updateProgressBar();
    }

	/**
	 * On Song Playing completed
	 * if repeat is ON play same song again
	 * if shuffle is ON play random song
	 * */
	@Override
	public void onCompletion(MediaPlayer arg0) {

		// check for repeat is ON or OFF
		if(isRepeat){
			// repeat is on play same song again
			playSong(currentSongIndex);
		} else if(isShuffle){
			// shuffle is on - play a random song
			Random rand = new Random();
			currentSongIndex = rand.nextInt((songsList.size() - 1) - 0 + 1) + 0;
			playSong(currentSongIndex);
		} else{
			// no repeat or shuffle ON - play next song
			if(currentSongIndex < (songsList.size() - 1)){
				playSong(currentSongIndex + 1);
				currentSongIndex = currentSongIndex + 1;
			}else{
				// play first song
				playSong(0);
				currentSongIndex = 0;
			}
		}
	}

	@Override
	 public void onDestroy(){
	 super.onDestroy();
	    mp.release();
	 }

}

Sending files to Emulator SDCard (For Testing)

To test this app in your android emulator you need to load your emulator with some songs. You can send files to emulator sdcard using adb tool which comes with Android SDK.

Navigate to your android SDK folder/platform-tools/ using command line. And using push command you can send files to sdcard. (Start your emulator before performing push command)

platform-tools> adb push "c:\Songs\White Flag.mp3" "/sdcard/"

Run your application.