Java StringBuilder get and set char and char array

// StringBuilder methods charAt, setCharAt, getChars and reverse.

public class Main 
{
   public static void main(String[] args)
   {/*from   w ww  . ja  v  a  2s  .co  m*/
      StringBuilder buffer = new StringBuilder("hello there");

      System.out.printf("buffer = %s\n", buffer.toString());
       System.out.printf("Character at 0: %s\nCharacter at 4: %s\n\n", 
         buffer.charAt(0), buffer.charAt(4));

      char[] charArray = new char[buffer.length()];
      buffer.getChars(0, buffer.length(), charArray, 0);
      System.out.print("The characters are: ");

      for (char character : charArray)
         System.out.print(character);

      buffer.setCharAt(0, 'H');
      buffer.setCharAt(6, 'T');
      System.out.printf("\n\nbuffer = %s", buffer.toString());

      buffer.reverse();
      System.out.printf("\n\nbuffer = %s\n", buffer.toString());
   } 
}