why `java.lang.SecurityException: Prohibited package name: java` is required?

Question

I created a class \"String\" and placed that in package \"java\" [ actually i wanted to create java.lang to see which class is loaded by classLoader as

Answer 1

User code is never allowed to put classes into one of the standard Java packages. That way, user code cannot access any package-private classes/methods/fields in the Java implementation. Some of those package-private objects allow access to JVM internals. (I'm thinking of SharedSecrets in particular.)