How to implement smooth switching between two interface windows?

To smoothly switch between two interface windows in Android, animations are usually used for transitioning between Activity or Fragment.

If it's about an Activity, you can apply the overridePendingTransition(int enterAnim, int exitAnim) method immediately after calling startActivity(). The parameters are animation resources, for example, from the res/anim folder.

Example:

Intent intent = new Intent(this, SecondActivity.class);
startActivity(intent);
overridePendingTransition(android.R.anim.fade_in, android.R.anim.fade_out);

For Fragment, you can use FragmentTransaction with the setCustomAnimations() method, where animations for entering, exiting, and returning are set:

FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left, R.anim.slide_in_left, R.anim.slide_out_right);
ft.replace(R.id.container, newFragment);
ft.addToBackStack(null);
ft.commit();

Thus, smoothness is achieved through animations that create visual effects during screen transitions.