java.lang.NoClassDefFoundError in java

This is normally a CLASSPATH problem. Try resetting the CLASSPATH, and/or make sure all third party JAR's are actually present in the correct locations. In some rare cases you will get this problem when the JVM has problems loading a third party jar due to version incompatibilities.

To set classpath in java, just see how to reset it. Following links may be useful to read:

• Path and classpath in java
• Determining current value of classpath
• Setting classpath in windows