Fragment replacing

Activity.java

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_subscription_purchase);
        container = findViewById(R.id.container);
   
        fragmentManager = getSupportFragmentManager();
        DataInputFragment fragment1 = DataInputFragment.newInstance();

        if (savedInstanceState == null) {
            FragmentTransaction fragmentTransaction = fragmentManager
                    .beginTransaction();
            fragmentTransaction.add(R.id.container, fragment1, DATA_FRAGMENT);
            fragmentTransaction.addToBackStack(DATA_FRAGMENT);

            fragmentTransaction.commit();
        }

    }

    private void replaceFragment() {
        FragmentTransaction fragmentTransaction = fragmentManager
                .beginTransaction();

        if (currentFragment == 1) {
            currentFragment++;
            CodeConfirmFragment fragment = CodeConfirmFragment.newInstance();
            fragmentTransaction
                    .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)

                    .replace(R.id.container, fragment,
                            CODE_CONFIRM_FRAGMENT)
                    .addToBackStack(CODE_CONFIRM_FRAGMENT);
        } else if (currentFragment == 2) {
            currentFragment++;
            PromocodeFragment fragment = PromocodeFragment.newInstance();
            fragmentTransaction
                    .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
                    .replace(R.id.container, fragment,
                            PROMOCODE_FRAGMENT)
                    .addToBackStack(PROMOCODE_FRAGMENT);
        } else if (currentFragment == 3) {
            currentFragment++;
            WebViewFragment fragment = WebViewFragment.newInstance();
            fragmentTransaction
                    .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
                    .replace(R.id.container, fragment,
                            WEBVIEW_FRAGMENT)
                    .addToBackStack(WEBVIEW_FRAGMENT);
        }

        Log.w("ww", "replaceFragment: " + fragmentManager.getBackStackEntryCount());
        fragmentTransaction.commit();
    }

    @Override
    public void onBackPressed() {
        currentFragment--;
        if (currentFragment == 0) fragmentManager.popBackStack();
        super.onBackPressed();
    }