Java Errors: ClassNotFoundError, NoClassDefFoundError, UnsupportedClassVersionError, LinkageError, ClassFormatError

As per JVM's parent-delegation class loading model a class can be loaded by either a bootstrap class loader or user defined class loader. During class loading the virtual machine can throw following errors and for the given reasons:

• NoClassDefFoundError
• If bootstrap class loader is directly invoked by the virtual machine and it is unable to load the binary data for the requested type.

• ClassNotFoundError
• If a user-defined class loader delegates to the bootstrap class loader or to a user-defined class loader which is then unable to load the binary data for the requested type, then the ClassNotFoundError is thrown. 

• ClassFormatError
•  If the class is located or produced but not in a proper structure
• If the class does not contain a superclass and is not class Object.

•  UnsupportedClassVersionError
• If the binary data is produced but is not part of a recognized version.

• LinkageError
• If class name already appears in the current class loader's name space.