sun.reflect.ConstructorAccessorImpl needs to be loaded in custom class loaders which only delegate public API class loads to their parent class loader.

OPERATING SYSTEM(S): Solaris 2.8
FULL JDK VERSION(S): java version "1.5.0_03"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_03-b07)
Java HotSpot(TM) Server VM (build 1.5.0_03-b07, mixed mode)
DESCRIPTION:
'CLTest' is the launcher program. It uses 'MyClassLoader' to load the class 'p1.LoadMe'. When 'CLTest'
then tries to create a new instance of 'p1.LoadMe', via reflection, it fails with the following error:
Exception in thread "main" java.lang.NoClassDefFoundError: sun/reflect/ConstructorAccessorImpl
        at sun.misc.Unsafe.defineClass(Native Method)
        at sun.reflect.ClassDefiner.defineClass(ClassDefiner.java:45)
        at sun.reflect.MethodAccessorGenerator$1.run(MethodAccessorGenerator.java:381)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.reflect.MethodAccessorGenerator.generate(MethodAccessorGenerator.java:377)
        at sun.reflect.MethodAccessorGenerator.generateConstructor(MethodAccessorGenerator.java:76)
        at sun.reflect.ReflectionFactory.newConstructorAccessor(ReflectionFactory.java:166)
        at java.lang.reflect.Constructor.acquireConstructorAccessor(Constructor.java:537)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:493)
        at java.lang.Class.newInstance0(Class.java:350)
        at java.lang.Class.newInstance(Class.java:303)
        at CLTest.main(CLTest.java:10)
To reproduce, cd to the directory containing CLTest.class, and use the following command:
 java -Dsun.reflect.noInflation=true CLTest
Note that -Dsun.reflect.noInflation=true forces the error to occur predictably. The error can also occur without this setting, but it depends on an internal threshold being exceeded.
TESTCASE:
CLTest.java:
import java.lang.reflect.Method;
public class CLTest {
 public static void main(String[] args) {
  try {
   MyClassLoader mcl = new MyClassLoader();
   Class c = mcl.loadClass("p1.LoadMe");
   c.newInstance();
  } catch(Exception e) {
   e.printStackTrace();
  }
 }
}
MyClassLoader.java:
import java.net.URL;
import java.net.URLClassLoader;
public class MyClassLoader extends URLClassLoader {
 public MyClassLoader() throws Exception {
  super(new URL[]{new URL("file:///" +
        System.getProperty("user.dir") +
        System.getProperty("file.separator") +
        "mclClassPath" +
        System.getProperty("file.separator"))});
 }
 
 public Class loadClass(String name) throws ClassNotFoundException {
  if(name.startsWith("java.")) {
   try {
    Class c = getParent().loadClass(name);
    if(c != null)
     return c;
   } catch(Exception e) {
   }
  }
  return findClass(name);
 }
}
LoadMe.java:
package p1;
import java.lang.reflect.Method;
public class LoadMe {
 public static void method1() {
  System.out.println("HELLO!");
 }
}
###@###.### 2005-05-05 16:46:23 GMT