Описание тега noclassdeffounderror
The Java Error thrown if the Java Virtual Machine or a ClassLoader instance tries to load in the definition of a class (as part of a normal method call or as part of creating a new instance using the new expression) and a valid representation of the class could not be constructed.
The Java Error thrown if the Java Virtual Machine or a ClassLoader instance tries to load in the definition of a class (as part of a normal method call or as part of creating a new instance using the new expression) and no definition of the class could be found.
The searched-for class definition existed when the currently executing class was compiled, but the definition can no longer be found.
This error is also caused by an uncaught exception in the static initializer of the class.
Don't confuse it with /questions/tagged/classnotfoundexception, it's a different kind of error, see the following links for more details: