title: Can't run my program after compiling says unsupported class version error
body: <p>I am a new user for linux. I just installed jdk1.7.0_02.rpm and tried to compile my program using <code>javac tester.java</code> When i try to run the file by <code>java tester</code> i get these errors</p>
  
  <pre><code>Exception in thread "main" java.lang.UnsupportedClassVersionError: tester : Unsupported major.minor version 51.0
  at java.lang.ClassLoader.defineClass1(Native Method)
  at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
  at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
  at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
  at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
  at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
  </code></pre>
  
  <p>Could not find the main class: tester. Program will exit.</p>
  
  <p>Then i checked the <em>java -version</em> and it was :</p>
  
  <pre><code>java version "1.6.0_22"
  OpenJDK Runtime Environment (IcedTea6 1.10.4) (fedora-61.1.10.4.fc16-i386)
  OpenJDK Server VM (build 20.0-b11, mixed mode)
  </code></pre>
  
  <p>Now how do i change this version ? I even installed jre1.7.0_02 but nothing changed !</p>
  
  <p>This is what is happening :</p>
  
  <p><img src="https://i.stack.imgur.com/ymUCe.png" alt="enter image description here"></p>