c002

.idea/misc.xml

@@ -5,7 +5,7 @@
       <configuration PROFILE_NAME="Debug" CONFIG_NAME="Debug" />
     </configurations>
   </component>
-  <component name="ProjectRootManager">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" default="true" project-jdk-name="1.8" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>
 </project>
\ No newline at end of file

.idea/test002.iml

@@ -2,7 +2,9 @@
 <module type="JAVA_MODULE" version="4">
   <component name="NewModuleRootManager" inherit-compiler-output="true">
     <exclude-output />
-    <content url="file://$MODULE_DIR$" />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$" isTestSource="false" />
+    </content>
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>

ff01.java

+public class ff01 {
+}