java - ThreadLocal variable for SimpleDateFormat (OR) new SimpleDateFormat - Correct? -

i come across this article , got confused

in our project in few places using threadlocal constructing threadlocal variable

in few other places constructing new object simpledateformat inside private local method.

example,

private date getconverteddate(string date){   simpledateformat sdf = new simpledateformat(); --> thread safe or not } 

could clarify in detail?

thanks.

variables created inside method - live on stack, are not shared across threads. each thread has it's own stack. declaring inside method, working it, forgetting it, make thread safe.

after comments here snippet:

public class deleteme {      public static void main(string[] args) throws exception {         deleteme me = new deleteme();         me.go();     }      public void go() throws exception {         final mutable mutable = new mutable();         new thread(new runnable() {             @override             public void run() {                 mutable.sett(57);             }         }).start();         /** main thread waits bit sure custom thread start */         thread.sleep(2000);         system.out.println(mutable.gett());     }      private class mutable{         public int t = 0;          public int gett() {             return t;         }          public void sett(int t) {             this.t = t;         }     } }