Java textfield decimal validation

Question

How can I validate user input contain only 5 digits with 2 decimal. I am using below code to check 5 digits, but how to check 2 decimal.

if (!id.equals("")) {
        try {
            Integer.parseInt(id);
            if (id.length() <= 5) {
                return true;
            }
        } catch (NumberFormatException nfe) {
            return false;
        }
    }

Answer 1

The DecimalFormat class will help you significantly with this. You can check that the user-input can be parsed according to a specific pattern.

The commons-validator library wraps this up in a convenient method call.

Answer 2

if(id.matches("\\d{5}\\.\\d{2}"))
    return true;
return false;

Answer 3

Any validation in Swing can be performed using an InputVerifier.

1. First create your own input verifier

   public class MyInputVerifier extends InputVerifier {
       public boolean verify(JComponent input) {
           String text = ((JTextField) input).getText();
           try {
               BigDecimal value = new BigDecimal(text);
               return (value.scale() <= Math.abs(2)); 
           } catch (NumberFormatException e) {
               return false;
           }
       }
   }
   

2. Then assign an instance of that class to your text field. (In fact any JComponent can be verified)

myTextField.setInputVerifier(new MyInputVerifier()); Of course you can also use an anonymous inner class, but if the validator is to be used on other components, too, a normal class is better.

Also have a look at the SDK documentation: JComponent#setInputVerifier.