title: Runnable JAR file error: Unsupported major.minor version 51.0
body: <p>I made an application in Java (version 7) with Eclipse (Indigo) when I exported my application interface on a Runnable JAR file on my computer and tried it worked fine, then I tried on another computer and I get this problem</p>
  
  <pre><code>Exception in thread "main" java.lang.UnsupportedClassVersionError: cliente/Princ
  ipal : Unsupported major.minor version 51.0
      at java.lang.ClassLoader.defineClass1(Native Method)
      at java.lang.ClassLoader.defineClassCond(Unknown Source)
      at java.lang.ClassLoader.defineClass(Unknown Source)
      at java.security.SecureClassLoader.defineClass(Unknown Source)
      at java.net.URLClassLoader.defineClass(Unknown Source)
      at java.net.URLClassLoader.access$000(Unknown Source)
      at java.net.URLClassLoader$1.run(Unknown Source)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.net.URLClassLoader.findClass(Unknown Source)
      at java.lang.ClassLoader.loadClass(Unknown Source)
      at java.lang.ClassLoader.loadClass(Unknown Source)
      at java.lang.Class.forName0(Native Method)
      at java.lang.Class.forName(Unknown Source)
      at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoa
  der.java:56)
  </code></pre>
  
  <p>I saw other post that this can be because the other computer have an older version of Java than mine, can somebody confirm this please?.</p>