java.lang.ClassNotFoundException for a specified class

Question

In my main I have the following statement

Class booki = Class.forName("Book");

which throws a java.lang.ClassNotFoundException exception

when I use the full path like Class booki = Class.forName("javatests.Book"); it is ok.

The main class and the Book class are in the same package, I also tried using import static javatests.Book.*; but still it throws the exception if I don't set the full path javatests.Book. Can someone explain to me why?

Answer 1

Class.forName resolves a fully qualified class name to the class. Since a method does not know where it is called from neither the package of the calling class nor imports in the calling class play any role.

Answer 2

From docs Class#forName

 public static Class<?> forName(String className)
                    throws ClassNotFoundException

Parameters:
className - the fully qualified name of the desired class.

So this will not throw ClassNotFoundException

Class booki = Class.forName("javatests.Book");  

For example, it is not needed to import java.lang.* package in java program but to load class Thread from java.lang package you need to write

Class t = Class.forName("java.lang.Thread");

the above code fragment returns the runtime Class descriptor for the class named java.lang.Thread