Resolving the error "Java compiler level does not match the version of the installed Java project" in Eclipse

I inherited a Java project created by another developer. When I opened it in Eclipse, I was able to build and run it, but Eclipse's Problems window showed an error, "Java compiler level does not match the version of the installed Java project."

Here's how I fixed it:

1. Right-click the project name in Project Explorer and select Properties. Then click Project Facets.

 

 

2. Click the dropdown arrow to the right of Java. Select the value 1.6, rather than 1.5.

 

 

3. Click OK. The error should disappear from the Problems window.