I don't know what to ask for. Need a dialog box for a erorr

Question

Can anyone tell me or show me a sample of code the will allow me to have an error dialog box.
I have a date that when the date format is wrong a dialog box pops up and informs the user of the correct date format.
This is the code that changes the background of the text box to red and stops the user for going on. I would be nice to have a dialog instead.
void DOBJText_focusLost(FocusEvent e) {
try
if (! DOBJText.getText().equals(""))
SimpleDateFormat df = new SimpleDateFormat("dd/mm/yyyy");
Date d = df.parse(DOBJText.getText());
DOBJText.setBackground(Color.white);
else
DOBJText.setBackground(Color.white);
catch (ParseException pe)
DOBJText.grabFocus();
DOBJText.setBackground(Color.red);
Thanks for any help
Craig

Answer 1

Sorry I should have looked Harder as I have found this.
the problem is that it opens up twice
anyone knows why this would happen ??
this is the code
void DOBJText_focusLost(FocusEvent e) {
try
if (! DOBJText.getText().equals(""))
SimpleDateFormat df = new SimpleDateFormat("dd/mm/yyyy");
Date d = df.parse(DOBJText.getText());
DOBJText.setBackground(Color.white);
else
DOBJText.setBackground(Color.white);
catch (ParseException pe)
JOptionPane.showMessageDialog( this,
"Date format needs to be DD/MM/YYYY", "Date Format Error",
JOptionPane.ERROR_MESSAGE );
}