Is there a thread safe date format ?

Question

I had format problem with date so I wrote a test program to see if I could reproduce it
this program runs 2 threads which translate a system date into a french date format
I used 3 method
1 - static java.text.DateFormat df = �����������������DateFormat.getDateInstance(DateFormat.SHORT,Locale.FRANCE);
the result is
thread 1 �04/02/02
thread 1 �04/02/02
thread 1 �04/02/02
thread 2 �04/02/02
thread 1 �04/02/2002 � ==> ?
thread 2 �04/02/02
thread 1 �04/02/2002 �==> ?
thread 2 �04/02/02
thread 1 �04/02/2002 �==> ?
thread 2 �04/02/02
thread 1 �04/02/2002
2 - static java.text.DateFormat df = ��������������DateFormat.getDateInstance(DateFormat.LONG,Locale.FRANCE);
thread 2 �4 f�vrier 2002
thread 2 �4 f�vrier 2002
thread 2 �4 f�vrier 2002
thread 2 �4 f�vrier 2002
thread 1 �0004 f�vrier 2002 �==> ?
thread 1 �4 f�vrier 2002
thread 1 �4 f�vrier 2002
3 - �SimpleDateFormat ("dd/MM/yyyy");
thread 2 �04/0002/2002 ==> ?
thread 1 �04/02/2002
thread 2 �04/0002/2002 ==> ?
thread 1 �04/02/2002
thread 2 �04/0002/2002 ==> ?
thread 1 �04/02/2002
thread 1 �04/02/2002
did I miss something ?
why it is not "thread safe " ?
any help ...
thranks denis
(my sample program)
import java.util.*;
import java.text.*;
public class th extends Thread {
/** T1 = getDateInstance(DateFormat.[SHORT-LONG],Locale.FRANCE); **/
//static java.text.DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT,Locale.FRANCE);
/** T2 = SimpleDateFormat **/
static private SimpleDateFormat _formatter = new SimpleDateFormat ("dd/MM/yyyy");
public String message ;
public th (String msg) {
this.message = msg ;
public void run () {
try {
while ( true ) {
printmess() ;
} catch (Exception e ) {System.out.println (" error  ") ; } ;
public void printmess( ) {
     /** T1 **/
     //String dateString = df.format(new Date());
     /** T2 **/          
String dateString = _formatter.format( new Date() );
System.out.println(message+" "+dateString);
public static void main(String[] args) {
Thread t1 = new th("thread 1 ") ;
Thread t2 = new th("thread 2 ") ;
t1.start();
t2.start();

Answer 1

I was able to reproduce your problem and found that make a minor change seems to have fixed the problem:
import java.util.*;
import java.text.*;
public class th extends Thread {
/** T1 = getDateInstance(DateFormat.[SHORT-LONG],Locale.FRANCE); **/
//static java.text.DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT,Locale.FRANCE);
/** T2 = SimpleDateFormat **/
// static private SimpleDateFormat _formatter = new SimpleDateFormat ("dd/MM/yyyy");
SimpleDateFormat _formatter;
public String message ;
public th (String msg) {
this.message = msg ;
_formatter = new SimpleDateFormat ("dd/MM/yyyy");
public void run () {
try {
while ( true ) {
printmess() ;
} catch (Exception e ) {System.out.println (" error ") ; } ;
public void printmess( ) {
/** T1 **/
//String dateString = df.format(new Date());
/** T2 **/
String dateString = _formatter.format( new Date() );
System.out.println(message+" "+dateString);
public static void main(String[] args) {
Thread t1 = new th("thread 1 ") ;
Thread t2 = new th("thread 2 ") ;
t1.start();
t2.start();
V.V.