Java Tutorial/Swing Event/CaretListener

Caret Events and Listeners

Whenever a caret changes its position or if text is selected, a caret event is fired by a text component. The class CaretEvent supports the methods getDot() and getMark() to retrieve the current location and the end position of a text selection, respectively.

   <source lang="java">

import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTextField; import javax.swing.event.CaretEvent; import javax.swing.event.CaretListener; public class CaretEeventListener {

 public static void main(String[] a) {
   JFrame frame = new JFrame();
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   JTextField textField = new JTextField();
   textField.addCaretListener(new CaretListener() {
     public void caretUpdate(CaretEvent e) {
       System.out.println(e);
     }
   });
   frame.add(new JScrollPane(textField));
   frame.setSize(300, 200);
   frame.setVisible(true);
 }

}</source>

Listen to CaretEvent with CaretListener

   <source lang="java">

import java.awt.FlowLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JTextField; import javax.swing.event.CaretEvent; import javax.swing.event.CaretListener; public class Main implements ActionListener {

 JTextField jtf = new JTextField(10);
 JButton jbtnGetTextUpper = new JButton("Get Text In Uppercase");
 Main() {
   JFrame jfrm = new JFrame("Demonstrate a Text Field");
   jfrm.setLayout(new FlowLayout());
   jfrm.setSize(240, 140);
   jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   jtf.setActionCommand("TF");
   jtf.addActionListener(this);
   jbtnGetTextUpper.addActionListener(this);
   jtf.addCaretListener(new CaretListener() {
     public void caretUpdate(CaretEvent ce) {
       System.out.println("Text in real time: " + jtf.getText());
     }
   });
   jfrm.add(jtf);
   jfrm.add(jbtnGetTextUpper);
   jfrm.setVisible(true);
 }
 public void actionPerformed(ActionEvent ae) {
   if (ae.getActionCommand().equals("TF")) {
     System.out.println("ENTER key pressed: " + jtf.getText());
   } else {
     String str = jtf.getText().toUpperCase();
     System.out.println("Button pressed: " + str);
   }
 }
 public static void main(String args[]) {
   new Main();
 }

}</source>