Difference between NoClassDefFoundException and ClassNotFoundException

A NoClassDefFoundException is thrown if a class is referenced with Java’s “new” operator (i.e. static loading) but the runtime system cannot find the referenced class.

Ex: Employee e = new Employee();


A ClassNotFoundException is thrown when an application tries to load in a
class through its string name using the following methods but no definition for the
class with the specified name could be found:

1. The forName(..) method in class - Class.
2. The findSystemClass(..) method in class - ClassLoader.
3. The loadClass(..) method in class - ClassLoader

Ex: Class employeeClass = Class.forName("com.samples.Employee") ;