Char index « StringBuffer « Character String « Development

Return	Method	Summary
char	charAt(int index)	Returns the char value in this sequence at the specified index.
void	setCharAt(int index, char ch)	The character at the specified index is set to ch.
void	getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)	Characters are copied from this sequence into the destination character array dst.
int	indexOf(String str)	Returns the index within this string of the first occurrence of the specified substring.
int	indexOf(String str, int fromIndex)	Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
int	lastIndexOf(String str)	Returns the index within this string of the rightmost occurrence of the specified substring.
int	lastIndexOf(String str, int fromIndex)	Returns the index within this string of the last occurrence of the specified substring.


public class Main {
  public static void main(String[] argv) {
    StringBuffer sb = new StringBuffer();
    sb.append("java2s.com");
    
    char ch =  sb.charAt(0);
    
    System.out.println(ch);

  }
}

 
public class Main {
  public static void main(String args[]) {
    StringBuffer sb = new StringBuffer("java2s.com");
    System.out.println("buffer before = " + sb);
    System.out.println("charAt(1) before = " + sb.charAt(1));

    sb.setCharAt(1, 'i');
    sb.setLength(2);
    System.out.println("buffer after = " + sb);
    System.out.println("charAt(1) after = " + sb.charAt(1));

  }
}


buffer before = java2s.com
charAt(1) before = a
buffer after = ji
charAt(1) after = i