For that you need to add change listener (a DocumentListener which reacts for change in the text) for your JTextField, and within actionPerformed(), you need to update the loginButton to enabled/disabled depending on the whether the JTextfield is empty or not. Below is what I found from this thread. yourJTextField.getDocument().addDocumentListener(new DocumentListener() { public void changedUpdate(DocumentEvent … Read more
Add a listener to the TextField’s textProperty: TextField textField = new TextField(); textField.textProperty().addListener((observable, oldValue, newValue) -> { System.out.println(“textfield changed from ” + oldValue + ” to ” + newValue); });
Add a listener to the underlying Document, which is automatically created for you. // Listen for changes in the text textField.getDocument().addDocumentListener(new DocumentListener() { public void changedUpdate(DocumentEvent e) { warn(); } public void removeUpdate(DocumentEvent e) { warn(); } public void insertUpdate(DocumentEvent e) { warn(); } public void warn() { if (Integer.parseInt(textField.getText())<=0){ JOptionPane.showMessageDialog(null, “Error: Please enter number … Read more