(For the time being, traditional desktop application developers have been spoiled. This does not mean that desktop application development is simpler than other development. As desktop application developers, we are now able to create various applications according to our ideas. Including myself, because I also started from making desktop programs. On the one hand, we have made it easier for desktop programs to interact with desktop operating systems, and to interact freely with any bottom hardware. This type of independent programming was originally for a small developer group to dare not venture into the muddy waters of mobile phone development.
Android Development Tutorial.pdf)