Caret Listener Interface is useful for monitoring the events that are related to the caret. Monitoring the caret event is important when we are working with the text editors. Caret means the point that is indicated by the cursor for the insertion. The caret event occurs in two cases, first, when the selection in the text component changes or the cursor moves. 

Caret Listener Interface in java

Caret Listener Interface is probably one of the most common Event Listener Interface that is used with the component related to the keyboard events. The best-case scenario for using the Caret Listener Interface may be to use it with The TextField or TextArea components. We will look at a very similar example in this article. We can also listen to the caret events by using another important Listener that we will be looking into, The Change Listener. But in today's example, our focus will be the caret Listener.   

Methods of The Caret Listener Interface

The caret Listener Interface is Like the Action Listener Interface. They both have only one method. In the Action Listener Interface, we have the actionPerformed method while in our CaretListener Interface we have the caretUpdate method. We will discuss this method in the following section.

caretUpdate(params)

This is the only method that should be implemented by the class that needs to use the caretListener Interface. This is the only reason why the CaretListener Interface in java has no Adapter class. This method is a void type and the method accepts only one parameter which is the object or instance of the Caret Event class. Before discussing the CaretEvent class let's have an example of the caretUpdate method. To see how it works we will use the JTextField Component ( JTextFiedl is a class in java swing which gives us the ability to create TextFiled Component. click here to learn more)  


Example of the CareListern Interface

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package AlixaProDev.EventListeners;

import javax.swing.*;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
import java.awt.*;

public class CaretListenerDemo{
    JFrame frame;
    JTextArea textField;
    JPanel panel;
    Font myFavFont;
    CaretListenerDemo(){
        // setting our Font and creating frame
        myFavFont = new Font("Mv Boli",Font.BOLD,34);
        frame = new JFrame();
        frame.setTitle("AlixaProdDev");

        
        // setting up and creating the TextArea
        textField = new JTextArea();
        textField.setLayout(new FlowLayout(FlowLayout.LEFT));
        textField.setBackground(Color.MAGENTA);
        textField.setPreferredSize(new Dimension(395,395));
        textField.setFont(myFavFont);
        textField.setForeground(Color.YELLOW);

        // adding caret Listner to our text Area
        textField.addCaretListener(new CaretListener() {
            @Override
            public void caretUpdate (CaretEvent e) {
                System.out.println("Got the Event");
            }
        });

        // setting up the panel to add our textArea to the panel
        panel = new JPanel();
        panel.setBounds(30,30,400,400);
        panel.add(textField);
        panel.setBackground(Color.red);

        // setting up the frame
        frame.setSize(new Dimension(500,500));
        frame.add(panel);
        frame.setLayout(null);
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}


// Created the main class to initiate our program
class Main{
    public static void main (String[] args) {
        new CaretListenerDemo();
    }
}


In the above Example when someone clicks on the text Field the CaretEvent will be created and the method caretUpdate will be invoked. The method caretUpdate needs, caretEvent as a parameter. Once we have the caretEvent Object here we can do whatever we want. The CaretEvent Object has the following method that we can call.  Here goes the Image of the Output of the above Program.

The CaretEvent Class and its Method

There are three Important methods that we can call on the object of the CaretEvent Object. the first method that we can call with the CaretEvent Object is getDot() method which returns the current Locatoin where the caret is located. the second method is getMark() which works in collaboration with the getDot() method both methods return the int values the getDot() method return the first index while the getMark() method reurns the other method.  

Summary and conclusion

aThe CaretListern Interface is recommended to use when you are working with the JTextComponetn class, Like JTextFiled or JTextArea. In the Above Example code. We did not make any crazy things. but you can by using the methods of the caretEvent class. It is up to you when you need to know such kind of Event Listener. I hope you now know much about the Caret Listener Interface. If you still have any questions related to this article or any other Java Project, Leave them in the comment section I will answer them.

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