Question about Observability of a Package

[Sergej Smoljanov]

JLS:7https://docs.oracle.com/javase/specs/jls/se7/html/jls-7.html#jls-7.4.3

The packages java, java.lang, and java.io are always observable.

i can`t do this:

class Test{
  public static void main(String[] arg){
     Serializable s =null;
  }
}

because i had no import.
why jls says that java.io are always observable?

[Marcus Biel]

I wouldn't bother to much on that.

I am a certified SCP 6 since 2008, and never heard this weird phrase.
However, I googled, no one really seems to understand what they meant, but here I found this on coderanch:
Observable packages


Hope that helps.


Marcus

[E Armitage]

It just says they are observable. It doesn't say that being observable means that you can use classes in those packages without importing them.