java - Data validation with JOptionPane -

i want perform data validation while joptionpane.i found following approach not satisfied it

import javax.swing.*; import java.util.regex.*;  public class validatejoptionpane {         public static void main(string[] args) {         string input = joptionpane.showinputdialog("enter number: ");                 pattern p = pattern.compile("[a-z,a-z,&%$#@!()*^]");                 matcher m = p.matcher(input);                 if (m.find()) {              joptionpane.showmessagedialog(null, "please enter numbers");                 }         } } 

it have been better , more sensible use regex detect characters can entered rather testing characters can't entered.

is there better , simpler way data validation joptionpane ? . feel regex overkill here.correct me if wrong:p

p.s beginner java

the long answer is, use documentfilter, see implementing document filter , documentfilter examples more details.

the problem is, need take control, can't rely on "simple", "helper" functionality provided joptionpane.showinputdialog, need access text field been used prompt user...

for example...

the following examples uses (slightly) modified version of patternfilter documentfilter examples

import java.util.regex.matcher; import java.util.regex.pattern; import javax.swing.jcomponent; import javax.swing.jlabel; import javax.swing.joptionpane; import javax.swing.jpanel; import javax.swing.jtextfield; import javax.swing.text.abstractdocument; import javax.swing.text.attributeset; import javax.swing.text.badlocationexception; import javax.swing.text.documentfilter; import javax.swing.text.documentfilter.filterbypass;  public class validatetest {      public static void main(string[] args) {         jtextfield field = new jtextfield(20);         pattern p = pattern.compile("[0-9]+");         ((abstractdocument) field.getdocument()).setdocumentfilter(new patternfilter(p));         int option = ask("enter number:", field);         if (option == joptionpane.ok_option) {             system.out.println("you have entered " + field.gettext());         }     }      public static int ask(string label, jcomponent comp) {          jpanel panel = new jpanel();         panel.add(new jlabel(label));         panel.add(comp);          return joptionpane.showoptiondialog(null, panel, label,                          joptionpane.ok_cancel_option,                          joptionpane.question_message, null, null, null);      }      public static class patternfilter extends documentfilter {          // useful every kind of input validation !         // insert pattern         // pattern must contain subpatterns can enter characters text component !         private pattern pattern;          public patternfilter(pattern p) {             pattern = p;         }          public void insertstring(filterbypass fb, int offset, string string, attributeset attr)                         throws badlocationexception {              string newstr = fb.getdocument().gettext(0, fb.getdocument().getlength()) + string;             matcher m = pattern.matcher(newstr);             if (m.matches()) {                 super.insertstring(fb, offset, string, attr);             } else {             }         }          public void replace(filterbypass fb, int offset,                         int length, string string, attributeset attr) throws                         badlocationexception {              if (length > 0) {                 fb.remove(offset, length);             }             insertstring(fb, offset, string, attr);         }     }  } 

now, little clever design, write simple helper class built internally , provided nice askfor(string label, pattern p) style method return string (or null if user canceled operation)