Question

I have been playing around with a CustomerClassLoader as i am trying to load a .class file into JUnitCore.runClasses(...); but i am getting the following error

Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: SimpleTest (wrong name: JUnit/SimpleTest)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
at Java.CustomClassLoader.access$000(CustomClassLoader.java:16)
at Java.CustomClassLoader$1.run(CustomClassLoader.java:45)
at java.security.AccessController.doPrivileged(Native Method)
at Java.CustomClassLoader.findClass(CustomClassLoader.java:33)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
.....

I don’t know what it wrong as I am passing in the correct class name and path for the class. here is the code that i am using

CustomClassLoader

import java.io.FileInputStream;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedExceptionAction;

public class CustomClassLoader extends ClassLoader {

String repoLocation = "C:/TempBINfolder/bin/JUnit/";

public CustomClassLoader() { }

public CustomClassLoader(ClassLoader parent) {
super(parent);
}

@Override
protected Class<?> findClass(final String name)
throws ClassNotFoundException {

AccessControlContext acc = AccessController.getContext();

try {
return (Class)AccessController.doPrivileged(
 new PrivilegedExceptionAction() {
  public Object run() throws ClassNotFoundException {

   FileInputStream fi = null;
   try {

    String path = name.replace('.', '/');
    fi = new FileInputStream(repoLocation + path
      + ".class");
    byte[] classBytes = new byte[fi.available()];
    fi.read(classBytes);
    return defineClass(name, classBytes, 0,
      classBytes.length);
   }catch(Exception e )
   {
    throw new ClassNotFoundException(name);
   }
  }
 }, acc);
} catch (java.security.PrivilegedActionException pae) {
return super.findClass(name);
}
}
}

And this is how i am calling it

ClassLoader cls= new CustomClassLoader(ClassLoader.getSystemClassLoader());
Class stringClass = null;
    try {
        stringClass = cls.loadClass("SimpleTest");
    } catch (ClassNotFoundException ex) {
        Logger.getLogger(CompilerForm.class.getName()).log(Level.SEVERE, null, ex);
    }
    try {
        stringClass.newInstance();
    } catch (InstantiationException ex) {
        Logger.getLogger(CompilerForm.class.getName()).log(Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        Logger.getLogger(CompilerForm.class.getName()).log(Level.SEVERE, null, ex);
    }

    JUnitCore.runClasses(stringClass);

Does anyone know why i am getting this error?

Answer 1

Change

stringClass = cls.loadClass("SimpleTest");

to
stringClass = cls.loadClass("JUnit.SimpleTest");

(i.e Add the fully qualified package name of the class file)

and

String repoLocation = "C:/TempBINfolder/bin/JUnit/";

to
String repoLocation = "C:/TempBINfolder/bin/";