java - Does throwing an exception change its state? -

i've run simple experiments this:

public static void main(string[] args) {     try {         nullpointerexception n = new nullpointerexception();         system.out.println(lists.newarraylist(n.getstacktrace()));         n.printstacktrace();         system.out.println(lists.newarraylist(n.getstacktrace()));         throw n;     } catch (nullpointerexception e) {         e.printstacktrace();         system.out.println(lists.newarraylist(e.getstacktrace()));     } } 

and output this:

java.lang.nullpointerexception     @ mytest.main(mytest.java:231) java.lang.nullpointerexception     @ mytest.main(mytest.java:231) [mytest.main(abstractscannertest.java:231)] [mytest.main(abstractscannertest.java:231)] [mytest.main(abstractscannertest.java:231)] 

but wonder if done exception when thrown. academic question, though relevant under circumstances if exception part of api , may or may not have been thrown when provided implementation.

no, throwable object not modified throw operation; passed call stack similar how method's argument be. throwables designed immutable objects , don't have setters, though support modifying stack trace rpc or similar frameworks can make sure appropriate error-tracing information included. said, throwable object other, , write throwable class had mutator methods called in catch block, though that's not usual.