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javaexceptionclassloader

Class.forName() and ClassNotFoundException

Say I have the following two classes:

public class MyClass {
    public String getDescription() {
        return "MyClass";
    }
}

and

public class MyClassLoader {
    public static void main (String[] argv) throws ClassNotFoundException {
        Class.forName("MyClass");
        System.out.println("MyClass class was successfully loaded");
    }
}

If both of these classes are in the default package, it runs fine, the class loads, and the world is beautiful. (If I were to delete the class MyClass, I would get a ClassNotFoundException, as expected.

However, if they are both in a package (let's say it's a package in Eclipse), and have the 

package myClassTestPackage;

declared in both, I get a ClassNotFoundException when I try to run it.

What causes this issue and how can I fix it? This is the simplest way I was able to reproduce an error I am experiencing in a much larger program.

Solution

  • That's because the Class.forName() method takes the fully qualified class name as parameter.

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

    So:

    Class.forName("myClassTestPackage.MyClass");