How do i validate ?

Question

problem : i want to validate my input with a regex.
my input is "27/12/2005 15:41:20";
my validation regex pattern is "dd/MM/yyyy HH:mm:ss"
How do i validate ?
I did the following but i can not TRUST because of those outputs. it does not validate
String str="27/12/2005  15:41:20";
     boolean tf=str.matches("dd/MM/yyyy HH:mm:ss");
     System.out.println(tf); // false !
     boolean tg=!str.matches("dd/MM/yyyy HH:mm:ss");
     System.out.println(tg); // true !
     str="27/12/2005  15:41";
     boolean tk=!str.matches("dd/MM/yyyy HH:mm:ss");
     System.out.println(tk); // true !Please suggest some validation trick .
Regards

Answer 1

it's a valid date according to that formatyes. valid date really.
i tried this also,
boolean okGood = java.util.regex.Pattern.matches("dd/MM/yyyy HH:mm:ss","27/12/2005  15:41:");
     System.out.println(okGood); this too does not not work.
In fact i have this code,
some relevalt piece of code which i am using
String startTime = (String)f.get("StartTime"); // f is dyna form in Struts
// blah
ActionErrors errors = new ActionErrors();
          if (startTime == null || (startTime.matches("dd/MM/yyyy HH:mm:ss"))) {
          errors.add("start time", new ActionError("startTime"));
          }This validation is not proper.
so, i want my user should input date only in that format , otherwise i am going to redirect him to the index.jsp page again for re-input with warning.