Java Android Mediaplayer

package com.audiomp3;

import android.media.MediaPlayer;
import android.os.Debug;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private SeekBar seekBar;
    private int indexSelect = 0;
    private int progress[] = new int[2];
    MediaPlayer medias[] = new MediaPlayer[2];

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initializeVariables();

        //mediaPlayer.setLooping(true);

        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

            @Override
            public void onProgressChanged(SeekBar seekBar, int progresValue, boolean fromUser) {

                if(fromUser == true) {

                    progress[indexSelect] = progresValue;
                    final float volume = (float) (1 - (Math.log(100 - progresValue) / Math.log(100)));

                    if (medias[indexSelect] != null) {
                        medias[indexSelect].setVolume(volume, volume);
                    }

                }

            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {}

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {}

        });

    }

    private void initializeVariables() {
        seekBar = (SeekBar) findViewById(R.id.seekBar);
    }


    private void audioStop(int index) {

        if(medias[index]!=null) {
            if(medias[index].isPlaying())
                medias[index].stop();
            medias[index].reset();
            medias[index].release();
            medias[index]=null;
        }
    }

    private void audioStart(int index, int audioFile) {

        seekBar.setProgress(progress[index]);

        if (medias[index] == null || !medias[index].isPlaying()){

            this.audioStop(index);

            indexSelect = index;
            medias[index] = MediaPlayer.create(this, audioFile);
            medias[index].start();

        }else{
            this.audioStop(index);
        }

    }


    public void btnStartClick(View view) throws IOException {this.audioStart(0, R.raw.iromi); }
    public void btnDosClick(View view) throws IOException {this.audioStart(1, R.raw.nicolo); }


}