AndroidStudio无法执行Java的main函数

FAILURE: Build failed with an exception.

* Where:
Initialization script 'C:\Users\lp\AppData\Local\Temp\ThreadDemo_main__.gradle' line: 21

* What went wrong:
A problem occurred configuring project ':app'.
> Could not create task ':app:ThreadDemo.main()'.
   > SourceSet with name 'main' not found.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 0s

解决方案：
项目目录下找.idea文件目录下gradle.xml文件
打开文件查找是否有delegatedBuild节点，如果没有就加上，如果有检查value是否为false

注意是在GradleProjectSettings标签下
改完之后保存重新build项目运行就可以了