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I have a login form where a user can enter his credentials to login. I have a JLabel that serves to display the text telling the user that the user name cannot be empty. This label is display after a user click the login button when the text field is empty.
I want that the moment the user starts typing in the text field the label with the information should disappear.How do I achieve this behavior?
Here is the code:
public class JTextFiledDemo {
private JFrame frame;
JTextFiledDemo() {
frame = new JFrame();
frame.setVisible(true);
frame.setSize(300, 300);
frame.setLayout(new GridLayout(4, 1));
frame.setLocationRelativeTo(null);
iniGui();
}
private void iniGui() {
JLabel error = new JLabel(
"<html><font color='red'> Username cannot be empty!<></html>");
error.setVisible(false);
JButton login = new JButton("login");
JTextField userName = new JTextField(10);
frame.add(userName);
frame.add(error);
frame.add(login);
frame.pack();
login.addActionListener((ActionEvent) -> {
if (userName.getText().equals("")) {
error.setVisible(true);
}
});
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JTextFiledDemo tf = new JTextFiledDemo();
}
});
}
}
944
You have to create DocumentListener:
DocumentListener dl = new DocumentListener()
{
@Override
public void insertUpdate(DocumentEvent de)
{
error.setVisible(false);
}
@Override
public void removeUpdate(DocumentEvent de)
{
//
}
@Override
public void changedUpdate(DocumentEvent de)
{
error.setVisible(false);
}
};
then for your text fields:
login.getDocument().addDocumentListener(dl);
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