Handling empty input in swing text box

Question

I am taking input from user and I want to display a popup if the input is empty. How to do this in Java Swing?

Answer 1

login_but.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e){

//System.out.print(F_user.getText());

String username = F_user.getText();

String password = F_pass.getText();

//System.out.print(password);

if(username.equals(""))

{

            JOptionPane.showMessageDialog(null,"Please enter username");

}

}

}

);