Exception in thread "main" java.lang.NoClassDefFoundError: weblogic.WLST.

[fusion@wlsadmin base_domain]$ cd /u02/Middleware_console/wlserver_10.3/server/bin
[fusion@wlsadmin bin]$ pwd
/u02/Middleware_console/wlserver_10.3/server/bin
[fusion@wlsadmin bin]$ java weblogic.WLST
Exception in thread "main" java.lang.NoClassDefFoundError: weblogic.WLST
   at gnu.java.lang.MainThread.run(libgcj.so.7rh)
Caused by: java.lang.ClassNotFoundException: weblogic.WLST not found in gnu.gcj.runtime.SystemClassLoader{urls=[file:./], parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}
   at java.net.URLClassLoader.findClass(libgcj.so.7rh)
   at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
   at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
   at gnu.java.lang.MainThread.run(libgcj.so.7rh)
[fusion@wlsadmin bin]$


++++++

Issue
+++++++
Exception in thread "main" java.lang.NoClassDefFoundError: weblogic.WLST.

It is unable to find this  class "java.lang.NoClassDefFoundError" and there is no issue with java
if it is issue with java then it will show message as "JAVA NOT FOUND SOMETHING".

(OR)
It is unable to load the class on the JVM.


[fusion@wlsadmin bin]$ which java
/usr/bin/java       
                               ===> when we install operating system the default java is                                                                installed in this locaiton "/usr/bin/java",Hence there is no issue with java.


[fusion@wlsadmin bin]$ echo $CLASSPATH             ==>Unable to load classes of weblogic server instance  on JVM so include weblogic product classes on JVM by setting env file.

[fusion@wlsadmin bin]$ 

+++++++++++++++++++++++++++++++++++++++++++++++
Let me set java which i have installed it on my OS.
+++++++++++++++++++++++++++++++++++++++++++++++
/u02/Middleware_console/wlserver_10.3/server/bin
[fusion@wlsadmin bin]$ export JAVA_HOME=/u02/jdk1.7.0_45
[fusion@wlsadmin bin]$ export PATH=$JAVA_HOME/bin:$PATH
[fusion@wlsadmin bin]$ which java            ==>Now my java is set but still it is not able to load this class file on JVM.
/u02/jdk1.7.0_45/bin/java
[fusion@wlsadmin bin]$ java weblogic.WLST
Error: Could not find or load main class weblogic.WLST
[fusion@wlsadmin bin]$ 



How can we tell operating system to use specific JVM?
/u02/Middleware_console/wlserver_10.3/server/bin
[fusion@wlsadmin bin]$ export JAVA_HOME=/u02/jdk1.7.0_45
[fusion@wlsadmin bin]$ export PATH=$JAVA_HOME/bin:$PATH
[fusion@wlsadmin bin]$ which java

or

[fusion@wlsadmin bin]$ ./setWLSEnv.sh
CLASSPATH=/u02/Middleware_console/patch_wls1036/profiles/default/sys_manifest_classpath/weblogic_patch.jar:/u02/jdk1.7.0_45/lib/tools.jar:/u02/Middleware_console/wlserver_10.3/server/lib/weblogic_sp.jar:/u02/Middleware_console/wlserver_10.3/server/lib/weblogic.jar:/u02/Middleware_console/modules/features/weblogic.server.modules_10.3.6.0.jar:/u02/Middleware_console/wlserver_10.3/server/lib/webservices.jar:/u02/Middleware_console/modules/org.apache.ant_1.7.1/lib/ant-all.jar:/u02/Middleware_console/modules/net.sf.antcontrib_1.1.0.0_1-0b2/lib/ant-contrib.jar:

PATH=/u02/Middleware_console/wlserver_10.3/server/bin:/u02/Middleware_console/modules/org.apache.ant_1.7.1/bin:/u02/jdk1.7.0_45/jre/bin:/u02/jdk1.7.0_45/bin:/u02/jdk1.7.0_45/bin:/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/home/fusion/bin

Your environment has been set.
[fusion@wlsadmin bin]$ java weblogic.WLST
Error: Could not find or load main class weblogic.WLST
[fusion@wlsadmin bin]$ echo $CLASSPATH  ==>Now classpath has been set ,because it has set in current session
[fusion@wlsadmin bin]$


++++++++++++++++++++++++++++
To resolve issue set 
++++++++++++++++++++++++++++++
. ./setWLSEnv.sh 

First dot is for "CURRENT SESSION"
Second dot is for "CURRENT TERMINAL"

Now try running java weblogic.WLST 



/u02/Middleware_console/wlserver_10.3/server/bin
[fusion@wlsadmin bin]$ . ./setWLSEnv.sh
CLASSPATH=/u02/Middleware_console/patch_wls1036/profiles/default/sys_manifest_classpath/weblogic_patch.jar:/u02/jdk1.7.0_45/lib/tools.jar:/u02/Middleware_console/wlserver_10.3/server/lib/weblogic_sp.jar:/u02/Middleware_console/wlserver_10.3/server/lib/weblogic.jar:/u02/Middleware_console/modules/features/weblogic.server.modules_10.3.6.0.jar:/u02/Middleware_console/wlserver_10.3/server/lib/webservices.jar:/u02/Middleware_console/modules/org.apache.ant_1.7.1/lib/ant-all.jar:/u02/Middleware_console/modules/net.sf.antcontrib_1.1.0.0_1-0b2/lib/ant-contrib.jar:

PATH=/u02/Middleware_console/wlserver_10.3/server/bin:/u02/Middleware_console/modules/org.apache.ant_1.7.1/bin:/u02/jdk1.7.0_45/jre/bin:/u02/jdk1.7.0_45/bin:/u02/jdk1.7.0_45/bin:/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/home/fusion/bin

Your environment has been set.
[fusion@wlsadmin bin]$ echo $CLASSPATH
/u02/Middleware_console/patch_wls1036/profiles/default/sys_manifest_classpath/weblogic_patch.jar:/u02/jdk1.7.0_45/lib/tools.jar:/u02/Middleware_console/wlserver_10.3/server/lib/weblogic_sp.jar:/u02/Middleware_console/wlserver_10.3/server/lib/weblogic.jar:/u02/Middleware_console/modules/features/weblogic.server.modules_10.3.6.0.jar:/u02/Middleware_console/wlserver_10.3/server/lib/webservices.jar:/u02/Middleware_console/modules/org.apache.ant_1.7.1/lib/ant-all.jar:/u02/Middleware_console/modules/net.sf.antcontrib_1.1.0.0_1-0b2/lib/ant-contrib.jar:
[fusion@wlsadmin bin]$ which java
/u02/jdk1.7.0_45/jre/bin/java
[fusion@wlsadmin bin]$ java weblogic.WLST

Initializing WebLogic Scripting Tool (WLST) ...

Welcome to WebLogic Server Administration Scripting Shell

Type help() for help on available commands

wls:/offline>


Happy learning !!!!!!!!!!!!