Car Park Ticket System with if statements which is half working...

Question

Hi
I have this following program which is a Car Park System, if you click the amount of hours, you can then pay for your ticket by clicking the money buttons on the left. The program is supposed to show a message dialog box when the amount turns to 0.00 or it shows a message with the amount of change if it goes under 0.00. The problem i am having is that the program works when i am using 50p's, �1's and �2's. But when i use several 10p's or 20p's, the amount reaches 0.00, but no message dialog box is shown, or sometimes when it reaches 0.00 it says Your change is �0.00 rather than just saying thank you.
The whole source code is here http://www.phpfi.com/89445
Thanks a lot for your help.

Answer 1

Like warneja said above........................
It's probably related to this:-
   double amount = 0;
        if ( amount == 0.00 )
              message.setText(" ");
                 JOptionPane.showMessageDialog( null,
              "Thank you", "EXACT AMOUNT", JOptionPane.INFORMATION_MESSAGE  );
         else if ( amount < 0.00 )
              message.setText(" ");
                 JOptionPane.showMessageDialog( null,
              "Your change is "+(pounds.format(Math.abs(amount))), "CHANGE", JOptionPane.INFORMATION_MESSAGE  );
         }Apart from changing the implementation tou might try something along the lines of
IF | amount | < eps THEN : Exact ammount of money reached.
where eps is a small number
'cos a lot of times you're going to get:
EXACT CHANGE reached - amount = 0.0000000000001
You could fing these things by putting in something like this:
At line 316
        System.out.println( "Amount is >"+ amount );
        if ( amount == 0.00 )
//......................then you'd be able to find your own bugs.
I can't thnk of the Java for Absolute Value now but try something like
           if( (amount < 0.10) && (amount > -0.10) )    // Less Than 10 Pennies
                 System.out.println( "Correct Money");
          }