Sometimes IDEA creates a new project, which may cause the editor to be unable to directly create java files, as shown in the figure below, so I tried the following methods:
（1）选择 File——>Project Structure——>Project Settings——>Modules
As shown in the new project, Java files cannot be created after new
(2) Select the folder where the java of the project is stored, set it as the source file, and click OK
(3) Click New again, you will find that you can create a new java.class file
If you think it's useful, like it, share it~