If you want your JTextField to be focused when your GUI shows up, you can use this: in = new JTextField(40); f.addWindowListener( new WindowAdapter() { public void windowOpened( WindowEvent e ){ in.requestFocus(); } }); Where f would be your JFrame and in is your JTextField.
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
Here’s how I did it: table.getSelectionModel().addListSelectionListener(new ListSelectionListener(){ public void valueChanged(ListSelectionEvent event) { // do some actions here, for example // print first column value from selected row System.out.println(table.getValueAt(table.getSelectedRow(), 0).toString()); } }); This code reacts on mouse click and item selection from keyboard.
Do not use a KeyListener for this as you’ll miss much including pasting of text. Also a KeyListener is a very low-level construct and as such, should be avoided in Swing applications. The solution has been described many times on SO: Use a DocumentFilter. There are several examples of this on this site, some written … Read more
You could create your own: import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.FocusEvent; import java.awt.event.FocusListener; import javax.swing.*; public class Main { public static void main(String[] args) { final JFrame frame = new JFrame(); frame.setLayout(new BorderLayout()); final JTextField textFieldA = new HintTextField(“A hint here”); final JTextField textFieldB = new HintTextField(“Another hint here”); frame.add(textFieldA, BorderLayout.NORTH); frame.add(textFieldB, BorderLayout.CENTER); … Read more
As this question re-appears quite often, I put some more effort in this answer then I would usually do. My vote goes to the JFormattedTextField. IMO each Swing developer should have an improved version of that class in his/her toolkit as it allows to validate almost anything you can think of by the correct choice … Read more
A JTextField was designed to use an ActionListener just like a JButton is. See the addActionListener() method of JTextField. For example: Action action = new AbstractAction() { @Override public void actionPerformed(ActionEvent e) { System.out.println(“some action”); } }; JTextField textField = new JTextField(10); textField.addActionListener( action ); Now the event is fired when the Enter key is … Read more
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