Hi everyone. I urgently need to know how to validate JTextField for email addresses and home no.

As you can see below, this is just a simple validation where if the user did not enter anything, a JOptionpane woud pop up. But how am i suppose to ensure that they must have a "@" sign as an input?
Pls help me by telling what are the codes that need to be done. It would be better if you can show a sample using these codes given below.

if(jTextFieldVolunteerUser.getText().trim().equals(""))

JOptionPane.showMessageDialog(myFrame, "Please enter your email address as your username.");