eclipse wrong VM related to java 1.7
Eclipse is not good at updating its configuration :). go ahead and check for the right JRE in the following spots:


Eclipse global preferences (Eclipse preferences > Java > Installed JREs)
Project properties > Libraries 


I had the same problem using ant build. The way to fix it there is by going to Run > External Tools > External tools configurations... and adjusting the JRE on the JRE tab