Pattern and Matcher problem. Help Please!

Question

I am trying to make the user enter a correct US$ in HTML(jsp format) ie 12.34 but not 12.3456. As far as i know, the regular expression below is correct for $$.
but the there is no error even if the user types 12.34567
can anyone help me please?
this is the code i wrote...
public static final int DATA_ENTRY = 1;
public static final int INVALID_CURRENCY = 2;
public static final int PROCESS_INPUT = 3;
int state;
String a; //data input from user
Pattern p = Pattern.compile("\\d{1,3}(?:(?:,\\d\\d\\d)*|\\d*)(?:\\.\\d\\d)?");
Matcher m = p.matcher(a);
state = DATA_ENTRY; // this is default
if (m.find() {
     state = PROCESS_INPUT;
else {
     state = INVALID_CURRENCY;

Answer 1

Here's two pattern strings that both require a two-place fraction for each entry but do not permit more than two places.
import java.util.regex.*;
public class snggun {
  public static void main(String[] args) {
    String input = (args.length > 0 ? args[0] : "10.00");
//    String mask = "\\d{1,3}(?:(?:,\\d\\d\\d)*|\\d*)(?:\\.\\d\\d)?";
    // requires two-place fraction
//    String mask = "^(\\d{1,3})(,(\\d\\d\\d))*(\\.\\d\\d)\\z";
    // requires two-place fraction
    String mask = "\\d{1,3}(?:(?:,\\d{3})*|\\d*)(\\.\\d{2})\\z";
    Pattern pattern = Pattern.compile(mask);
    Matcher match = pattern.matcher(input);
    System.out.println("input = " + input + " qualifies " + match.find());
    if(match.find())
      for(int j = 0; j <= match.groupCount(); j++)
        System.out.println("group " + j + "  " + match.group(j));
}