code: @Override
  	public boolean validate(final Problems problems, final String compName, final String text) {
  		try {
  			final double d = Double.parseDouble(text);
  			if (d < 0D) {
  				final String problem = ValidationBundle.getMessage(NonNegativeNumberValidator.class, "ERR_NEGATIVE_NUMBER", compName); // NOI18N
  				problems.add(problem);
  				return false;
  			}
  		} catch (final NumberFormatException e) {
  			// do nothing - if someone wants not-a-number validation, they
  			// should
  			// chain an IntegerDocumentValidator or similar
  		}
  		return true;
  	}
docs: /*
  (non-Javadoc)
  
  @see
  com.fs.commons.desktop.validation.Validator#validate(com.fs.commons.desktop.
  validation.Problems, java.lang.String, java.lang.Object)