project facet Java version 6.0 is not supported problem in eclipse IDE

The problem we can face is due to lower version of java being specified in your facet settings.
We get this problem when we try to run Web application/project in eclipse IDE  and try to run in apache tomcat server.
The solution of this problem is:
Goto project properties -> Select Project Facets -> Check the Java version, if it is other than java 5.0 then click on Add/Remove Project Facets. 
A new pop-up will open select "Facets Project" from the configurations dropdown.
Now you will see a Project Facet named "Java". select the checkbox and change the version to 5.0 and click finish.
Clean build your workspace. 


Now It should work.
Thanks.