How to browse the ViewPager program?

Please tell me how to browse the page ViewPager programmatically, to achieve some kind of event. In my case - at the end of playback of an audio file attached to a page. Here is the code if you need to see the implementation:

public class SliderActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener { static final String TAG = "myLogs"; ViewPager viewPager; CustomSwipeAdapter adapter; ToggleButton toggleButton; ImageButton imageButton; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); setContentView(R.layout.activity_slider); imageButton = (ImageButton) findViewById(R.id.imageButtonHome); View.OnClickListener clickHome = new View.OnClickListener() { @Override public void onClick(View v) { if(mp !=null && mp.isPlaying()){ mp.stop(); } GoHome(); } }; imageButton.setOnClickListener(clickHome); /* * Читаем json и создаем из него объект книги bookFiles */ Gson gson = new Gson(); int bookId = GetBookId(); String fileName = "book_" + bookId + ".json"; String gsResult = MyJSON.getData(getApplicationContext(), fileName); BookFiles bookFiles = gson.fromJson(gsResult, BookFiles.class); final String folderB = "bookfiles_" + bookId; /* Получаем из объекта bookFiles массивы путей к файлам книги */ ArrayList<String> pagesFiles = bookFiles.getPagesPath(); final ArrayList<String> soundsFiles = bookFiles.getSoundsPath(); viewPager = (ViewPager) findViewById(R.id.view_pager); viewPager.setPageTransformer(true, new ZoomOutPageTransformer()); adapter = new CustomSwipeAdapter(this, pagesFiles); viewPager.setAdapter(adapter); toggleButton = (ToggleButton) findViewById(R.id.imageButtonPlay); //слушаем номер слайда при перелистывании viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() { @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { String nameS = Uri.parse(soundsFiles.get(position)).getLastPathSegment(); if(mp != null){ mp.stop(); } getMedia(nameS, folderB); toggleButton.setOnCheckedChangeListener(SliderActivity.this); if (toggleButton.isChecked()){ mp.start(); } } @Override public void onPageScrollStateChanged(int state) { } }); ViewPager.OnPageChangeListener listener = new ViewPager.SimpleOnPageChangeListener() { @Override public void onPageSelected(int position) { String nameS = Uri.parse(soundsFiles.get(position)).getLastPathSegment(); if(mp != null){ mp.stop(); } getMedia(nameS, folderB); toggleButton.setOnCheckedChangeListener(SliderActivity.this); if (toggleButton.isChecked()){ mp.start(); } } }; viewPager.addOnPageChangeListener(listener); listener.onPageSelected(0); } public int GetBookId() { Intent intent = getIntent(); int bookId = intent.getIntExtra("bookId", 1); return bookId; } @Override public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { if (isChecked) mp.start(); else if (mp.isPlaying()) { mp.pause(); } } public void getMedia(String nameS, String folderB) { try { final String soundPath = String.valueOf(getApplicationContext().getExternalFilesDir(folderB)); final Uri souF = Uri.fromFile(new File(soundPath, nameS)); final MediaPlayer mp = MyPlayer.getMp(getApplicationContext(), souF); mp.setAudioStreamType(AudioManager.STREAM_MUSIC); } catch (Exception e) { e.printStackTrace(); } } private void GoHome() { new Handler().postDelayed(new Runnable() { @Override public void run() { Intent intent = new Intent(SliderActivity.this, MainActivity.class); startActivity(intent); finish(); } }, 10); } }