I just want to create a very basic application in android that plays a audio file based on a URL input.I have made the Application and I would like it to be reviewed based on good programming practices.This is the first time that I have used the Media Player class it works as I would like it to but I am sure my code can be optimized and improved. Following is my code for the MediaPlayerActivity.class that I have built:-

public class MediaPlayerActivity extends AppCompatActivity {      TextView tvArtistName, tvSongName;     ImageView ivPlay, ivPrev, ivNext, ivPause;      MediaPlayer mediaPlayer = new MediaPlayer();      private double startTime = 0;     private double finalTime = 0;      private Handler myHandler = new Handler();     ;     private int forwardTime = 5000;     private int backwardTime = 5000;     private SeekBar seekbar;     public static int oneTimeOnly = 0;      ActionBar actionBar;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_media_player);         actionBar = getSupportActionBar();         actionBar.hide();          tvArtistName = (TextView) findViewById(R.id.tvArtistName);         tvSongName = (TextView) findViewById(R.id.tvSongName);         ivPlay = (ImageView) findViewById(R.id.iv_play);         ivPause = (ImageView) findViewById(R.id.iv_pause);         ivNext = (ImageView) findViewById(R.id.iv_next);         ivPrev = (ImageView) findViewById(R.id.iv_prev);         seekbar = (SeekBar) findViewById(R.id.seekBar);         seekbar.setClickable(false);           Intent intent = getIntent();         if (intent.getExtras() != null) {             final String url = intent.getStringExtra("url");             String song = intent.getStringExtra("song");             String artist = intent.getStringExtra("artist");              tvArtistName.setText(artist);             tvSongName.setText(song);              mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);             mediaPlayer = MediaPlayer.create(getApplicationContext(), Uri.parse(url));               ivPlay.setOnClickListener(new View.OnClickListener() {                 @Override                 public void onClick(View view) {                     // Toast.makeText(getApplicationContext(), "Playing sound", Toast.LENGTH_SHORT).show();                     if (mediaPlayer.isPlaying()) {                         mediaPlayer.stop();                         mediaPlayer.reset();                     }                     mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {                         @Override                         public void onCompletion(MediaPlayer mediaPlayer) {                             mediaPlayer.stop();                             mediaPlayer.reset();                         }                     });                     mediaPlayer.start();                     finalTime = mediaPlayer.getDuration();                     startTime = mediaPlayer.getCurrentPosition();                      if (oneTimeOnly == 0) {                         seekbar.setMax((int) finalTime);                         oneTimeOnly = 1;                     }                      seekbar.setProgress((int) startTime);                     myHandler.postDelayed(UpdateSongTime, 100);                     ivPlay.setVisibility(View.GONE);                     ivPause.setVisibility(View.VISIBLE);                  }             });              ivPause.setOnClickListener(new View.OnClickListener() {                 @Override                 public void onClick(View view) {                     Toast.makeText(getApplicationContext(), "Pausing sound", Toast.LENGTH_SHORT).show();                     mediaPlayer.pause();                     ivPause.setVisibility(View.GONE);                     ivPlay.setVisibility(View.VISIBLE);                 }             });              ivNext.setOnClickListener(new View.OnClickListener() {                 @Override                 public void onClick(View view) {                     int temp = (int) startTime;                      if ((temp + forwardTime) <= finalTime) {                         startTime = startTime + forwardTime;                         mediaPlayer.seekTo((int) startTime);                         //Toast.makeText(getApplicationContext(),"You have Jumped forward 5 seconds",Toast.LENGTH_SHORT).show();                     } else {                         //Toast.makeText(getApplicationContext(),"Cannot jump forward 5 seconds",Toast.LENGTH_SHORT).show();                     }                 }             });              ivPrev.setOnClickListener(new View.OnClickListener() {                 @Override                 public void onClick(View view) {                     int temp = (int) startTime;                      if ((temp - backwardTime) > 0) {                         startTime = startTime - backwardTime;                         mediaPlayer.seekTo((int) startTime);                         //Toast.makeText(getApplicationContext(),"You have Jumped backward 5 seconds",Toast.LENGTH_SHORT).show();                     } else {                         //Toast.makeText(getApplicationContext(),"Cannot jump backward 5 seconds",Toast.LENGTH_SHORT).show();                     }                  }             });         }     }      @Override     public void onBackPressed() {         super.onBackPressed();         mediaPlayer.release();         mediaPlayer = null;         seekbar.setProgress(0);         startTime = 0;         finalTime = 0;     }      private Runnable UpdateSongTime = new Runnable() {         public void run() {             if (mediaPlayer!=null)             {                 startTime = mediaPlayer.getCurrentPosition();                 seekbar.setProgress((int) startTime);                 myHandler.postDelayed(this, 100);             }         }     }; } 

Any help for improvement is appreciated.Thank you.