Possible scenario of when you can get JNI or JVM or classloader error

Sample class
----------------

package java.util;

public class ArrayListClass {
public static void main(String[] args) {

ArrayList list = new ArrayList();
HashMap hmap = new HashMap();
hmap.put(1,1);
hmap.put(2,2);
hmap.put(3,3);
hmap.put(4,4);
hmap.put(5,5);
hmap.put(6,6);

list.add(hmap);

Iterator itr = list.iterator();
System.out.println("ArrayListClass on Iterators.......");
while(itr.hasNext()){
System.out.println(itr.next());
}
}
}


Errors : 
---------

Since you have declared the same name as the java.util Package you will get the error 
as 

JNI or JVM or Classloader error.

Exception in thread "main" java.lang.SecurityException: Prohibited package name: java.util
at java.lang.ClassLoader.preDefineClass(ClassLoader.java:659)
at java.lang.ClassLoader.defineClass(ClassLoader.java:758)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:495)