ClassNotFoundException和ClassDefNotFoundException之间有什么区别

Question

What is the difference between ClassNotFoundException and ClassDefNotFoundException I know that both are subclass of Exception .

Got some explanation for ClassNotFoundException from this question. What is the difference between NoClassDefFoundError and ClassNotFoundException?

I read Java doc for ClassDefNotFoundException and it says:

ClassDefNotFoundException is thrown when the definition of a class cannot be found be the OWB typing system.

Please elaborate above statement, I am unaware of OWB typing system. And what exactly is the difference between both the classed and when these Exceptions are raised.

Answer 1

ClassNotFoundException is a core Java exception.

ClassDefNotFoundException is an "Oracle Warehouse Builder" exception (which in all likelihood just wraps a ClassNotFoundException ).

Answer 2

A ClassNotFoundException is thrown when the reported class is not found by the ClassLoader. This typically means that the class is missing from the CLASSPATH .

Suppose we have a class named as X has reference to Class Y. Classloader loads the class X, It's loaded now it goes through linking phase where it goes through three different subphases.

1. Verification-phase
2. Prepare-phase
3. Resolve-phase.

Now when it goes through Resolve-phase and this phase try to resolve reference of Y and unfortunately it does not find the definition of class Y, then It will be ClassDefNotFoundException for Class Y and it will wrap 'ClassNotFoundException' for class X.