＞ Could not create task ‘:app:MyTest.main()‘. ＞ SourceSet with name ‘main‘ not found.问题修复

Android studio 无法执行Java类的main方法问题及解决方法 

FAILURE: Build failed with an exception.

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

* What went wrong:
A problem occurred configuring project ':app'.
> Could not create task ':app:MyTest.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 9s
9:10:31: Task execution finished 'MyTest.main()'.

解决方法： 在.idea文件夹下的gradle.xml文件中 标签下添加，然后重新运行就可以了