java error

1. When migrating an eclipse project, if you encounter
"Project facet Java version 1.7 is not supported."
jdk1.7 in the project is not supported. It means that the project is compiled by other versions of jdk, and it will report that the version is not supported when running in eclipse.
Solution:
Method 1, select the project Properties, select Project Facets, right-click and select Java, Change Version....
Method 2, there is a .settings folder in the project directory, and there is a org.eclipse.wst.common.project.facet.core.xml file in this folder, the content is as follows;

<?xml version="1.0" encoding="UTF-8"?>
<faceted-project>
<fixed facet="jst.java"/>
<fixed facet="jst.web"/>
<installed facet="jst.web" version="2.4"/>
<installed facet="jst.java" version="7.0"/>
</faceted-project>

<installed facet="jst.java" version="7.0"/>

change into

<installed facet="jst.java" version="6.0"/>

two,