fixed Unsupported major.minor version 51.0

Recently I moved to Java 7.  I was doing coding , I opened my old project which was in  Java 1.6.
my eclipse started giving me this error which is :
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Unsupported major.minor version 51.0
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java.lang.UnsupportedClassVersionError: com/javapapers/spring/SpringEmail : Unsupported major.minor version 51.0

at java.lang.ClassLoader.defineClass1(Native Method)

at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)

at java.lang.ClassLoader.defineClass(ClassLoader.java:615)

at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)

at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)

at java.net.URLClassLoader.access$000(URLClassLoader.java:58)

at java.net.URLClassLoader$1.run(URLClassLoader.java:197)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(URLClassLoader.java:190)

at java.lang.ClassLoader.loadClass(ClassLoader.java:306)

at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)

at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

Exception in thread "main" 

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I found solution for this 

it was version mismatch with jre

J2SE 8 = 52,

J2SE 7 = 51,

J2SE 6.0 = 50,

J2SE 5.0 = 49,

JDK 1.4 = 48,

JDK 1.3 = 47,

JDK 1.2 = 46,

JDK 1.1 = 45

I recompile with java 1.6

http://mytechnologythought.blogspot.in/2013/06/starting-tomcat-v70-server-at-localhost.html