POBIERANIE SEEKBARA DO ZMIENNEJ
SeekBar seekBar1 = findViewById(R.id.seekBar1);

POBIERANIE WARTOSCI SEEKBARA SPOSOB NUMER 1
int wartoscSeekbara = seekBar1.getProgress();

POBIERANIE WARTOSCI SEEKBARA SPOSOB NUMER 2
seekBar1.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
  @Override
  public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
    // zmienna progress zawiera wartosc seekbara USUN KOMENTARZ
  }

  @Override
  public void onStartTrackingTouch(SeekBar seekBar) {

  }

  @Override
  public void onStopTrackingTouch(SeekBar seekBar) {

  }
});