StringBuffer methods charAt, setCharAt, getChars and reverse : StringBuffer StringBuilder « Development « Java Tutorial

public class MainClass
   public static void main( String args[] )
      StringBuffer buffer = new StringBuffer( "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\nbuf = %s", buffer.toString() );

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

6.15.StringBuffer StringBuilder
6.15.1.StringBuffer and StringBuilder
6.15.2.You can also create a StringBuffer object using a reference stored in a variable of type String:
6.15.3.Creating a String Object From a StringBuffer Object
6.15.4.Creating a StringBuffer object with a specific value for the capacity
6.15.5.Check the capacity of StringBuilder object
6.15.6.Adding String to a StringBuffer Object
6.15.7.The append() method returns a reference to the extended StringBuffer object
6.15.8.Calling append() method to construct a StringBuffer object
6.15.9.Appending a Substring: append part of the aString object to the buf object
6.15.10.Appending Basic Types: long, double
6.15.11.Appending a subset of the elements from a char array
6.15.12.StringBuffer methods charAt, setCharAt, getChars and reverse
6.15.13.StringBuffer methods insert, delete and deleteCharAt
6.15.14.Convert digit to character with Character.forDigit
6.15.15.Inserting Strings
6.15.16.The Length of a StringBuffer Object
6.15.17.Changing the StringBufer Length for a StringBuffer Object
6.15.18.To find out a StringBuffer object's capacity
6.15.19.The ensureCapacity() method changes the default capacity of a StringBuffer object
6.15.20.Finding the Position of a Substring
6.15.21.Specifying the index position in the buffer where the search is to start
6.15.22.Replacing a Substring in the Buffer
6.15.23.Extracting Characters From a Mutable String: charAt() and getChars() methods
6.15.24.Changing a single character in a StringBuffer object
6.15.25.Using the deleteCharAt() method to remove a character from a StringBuffer object at the index position
6.15.26.Removing several characters from a StringBuffer object
6.15.27.Remove substring from StringBuilder
6.15.28.Deletes text from the StringBuilder object
6.15.29.Reversing the sequence of characters in a StringBuffer object with the reverse() method