When reading some documentation about assertions, I found:
java -ea -dsa
"Enables assertions in general, but disables assertions in system classes."
Which are the system classes?
According to the assertions documentation, system classes are classes "which do not have an explicit class loader", i.e. the classes loaded by the bootstrap classloader. AFAIK that means the contents of rt.jar, the entire standard API.
Per the same documentation system classes are classes which do not have a class loader. Could be the classes found on the boot class path
来源：https://stackoverflow.com/questions/2670269/which-are-javas-system-classes