Who is the caller and who is the callee in this callback pattern?

Question

Hi,
Could someone tell me which method is the caller and which is the callee in the following code? Please be as detailed as possible in your explanation.
Thank you in advance!
public class TimePrinter implements ActionListener {
     public void actionPerformed(ActionEvent evt) {
          Date now = new Date();
          System.out.println("At the tone, the time is " + now);
          Toolkit.getDefaultToolkit().beep();
public class TimerTest {
     public static void main(String[] args) {
          ActionListener listener = new TimePrinter();
          int delay = 10000; //Delays 10 seconds
          //Constructs a timer that calls the listener once every 10 seconds.
          Timer t = new Timer(delay, listener);
          t.start();
          JOptionPane.showMessageDialog(null, "Quit program?");
          System.exit(0);
}

Answer 1

jverd,
Thank you again for responding to this thread!
Here is the code:
//TimePrinter.java
import java.util.*;
import java.awt.*;
import java.awt.event.*;
public class TimePrinter implements ActionListener {
      public void actionPerformed(ActionEvent evt) {
             Date now = new Date();
             System.out.println("At the tone, the time is " + now);
             Toolkit.getDefaultToolkit().beep();
//TimerTest.java
import java.awt.event.*;
import javax.swing.*;
import javax.swing.Timer;
import java.util.*;
import java.awt.*;
public class TimerTest {
        public static void main(String[] args) {
                ActionListener listener = new TimePrinter();
                int delay = 10000; //Delays 10 seconds
               //Constructs a timer that calls the listener once every 10 seconds.
               Timer t = new Timer(delay, listener);
               t.start();
              JOptionPane.showMessageDialog(null, "Quit program?");
              System.exit(0);
}Prior to posting to this forum, I actually have done some research and learned the following:
"A callback in programming is executable code that is passed as an argument to other code. "
With this definition, in the above example "actionPerformed" in the TimePrinter class is the executable code, it's being passed to Timer(delay, listener). So the caller here is Timer(delay, listener), callee is the actionPerformed() method, as it is the method that is being called. This is how I interpret it. Am I correct? My question is still which is the caller and callee in this example.
Note, I don't come here often and didn't even know that you could format the text. I formated my msg as you requested, don't know how the text will turn out.
Regards,
Eric
One more question: I tried formatting by placing my code like this my source, what it did is to place the text in a blue area but didn't indent like the source did (I manually indented it). How do I keep the format as the original code?
Edited by: ericdunn on Jul 29, 2009 12:40 PM
Edited by: ericdunn on Jul 29, 2009 12:45 PM