Replace the first 3 characters with some text in Java

import java.awt.Font;
/*from  w w  w  . jav a 2  s.  co  m*/
import javax.swing.JFrame;
import javax.swing.JTextArea;

public class Main extends JFrame {

  public Main() {
    JTextArea textArea = new JTextArea("Initial Text");
    textArea.setFont(new Font("LucidaSans", Font.PLAIN, 40));
    add(textArea);    

    int start = 0;
    int end = 3;
    textArea.replaceRange("java2s.com", start, end);
  }

  public static void main(String[] args) {
    JFrame frame = new Main();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.pack();
    frame.setVisible(true);
  }
}