public class CapitalsActivity extends AppCompatActivity {
    private Button nextButton;
    private int index = 0;
    private TextView questionTextView;

    private Questions[] questions = new Questions[]{
            new Questions(R.string.question_france, "Париж"),
            new Questions(R.string.question_sweden, "Стокгольм"),
            new Questions(R.string.question_poland, "Варшава")
    };

    private void updateQuestion() {
        int question = questions[index].getTextResId();
        questionTextView.setText(question);
    }

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

        nextButton = (Button) findViewById(R.id.next_button);
        nextButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                index = (index + 1) % questions.length;
                updateQuestion();
            }
        });

    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}