public java.lang.StringBuffer append(char c){
  internal.append(c);
  return this;
}

public java . lang . StringBuffer append ( char c ) { internal . append ( c ) ; return this ; }
appends the string representation of the char argument to this string buffer . the argument is appended to the contents of this string buffer . the length of this string buffer increases by 1 . the overall effect is exactly as if the argument were converted to a string by the method string . valueof ( char ) and the character in that string were then appended to this stringbuffer object .
