Eclipse appears
Java compiler level does not match the version of the installed Java project facet
Error message
the reason:
It is caused by the inconsistency between the selected version of the Java Compiler and the java version specified in'Project Facets'.
Just modify it to be consistent,
There are many ways to modify the'Project Facets' version,
1. You can directly modify the corresponding configuration file
Modify facet="java" item in .settings/org.eclipse.wst.common.project.facet.core.xml in the project directory;
2. Modify through Eclipse, right-click the project=>Properties=>Project Facets to modify the Java version
