(Students who have played with Android phones should be very clear about the mechanism of the mobile phone's anyhow screen. Most games cannot be switched from one screen to another. Some games can only be played vertically, while others can only be played horizontally. Why should games be forced to be a single screen in development? The simple reason is that there are too many problems in the dark area of the switching screen. It is too difficult to develop, so most games will force the horizontal screen or vertical screen. Today, I used a small example to take the students to check some development skills of reverse screen switching in Android development.)