Its because of Java version mismatch.Just need to double check your system environment variable JDK_HOME
and JRE_HOME
point to JAVA 1.7 as well.
You must run and compile your application with the same version of Java.
If you're using Eclipse you should do 2 things:
In Eclipse, click on "Window > Preferences", and in the window that appears, on the left side, under "Java", click on "Installed JREs", click on "Add..." and navigate to the folder that contains the JDK.
Right-click on your project and click on "Properties", in the window that appears, on the left side, click on "Java Compiler" and uncheck "Use compliance from execution environment on the Java Build Path", this allows you to choose in the the list "Compiler compilance level" the same version that you set in the previous step.
Hope that helps.