When I looked at the source code, I found that the structure between classes was complicated. I didn't know where to go when I clicked and clicked. I was a little dizzy.
File-->Settings Open the settings interface
Navigate to plugins and enter UML, as shown in the following figure:
Make sure that the UML Support box is checked, click apply in the lower right corner, and restart the idea
Then find a java class file, right click on Diagram
