[ckan-dev] starting pycharm IDE failed, displays "Exception in thread "main" java.lang.NoClassDefFoundError: com/intellij/idea/Main" error information, can you help me to solve this problem

[bupt bupt]

hello everyone,
       now I am using pycharm IDE software. But when I start it, it
displays
"Exception in thread "main" java.lang.NoClassDefFoundError:
com/intellij/idea/Main"
error information, Can you help me to ensure where is the problem? And how
can I solve this problem? Thank you very much~~
       The terminal output details are as followed:

"
ys at ys-VirtualBox:~/softwaresetup$ . pycharm-2.7.1/bin/pycharm.sh
OpenJDK Runtime Environment (IcedTea6 1.12.3) (6b27-1.12.3-0ubuntu1~12.04.1)
OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)
OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)
WARNING: You are launching the IDE using OpenJDK Java runtime.

         ITS KNOWN TO HAVE PERFORMANCE AND GRAPHICS ISSUES!
         SWITCH TO THE ORACLE(SUN) JDK BEFORE REPORTING PROBLEMS!

NOTE:    If you have both Oracle (Sun) JDK and OpenJDK installed
         please validate either PYCHARM_JDK, JDK_HOME, or JAVA_HOME
environment variable points to valid Oracle (Sun) JDK installation.
         See http://ow.ly/6TuKQ for more info on switching default JDK.

Press Enter to continue.

Exception in thread "main" java.lang.NoClassDefFoundError:
com/intellij/idea/Main
Caused by: java.lang.ClassNotFoundException: com.intellij.idea.Main
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: com.intellij.idea.Main. Program will exit.
"
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