public java.lang.StringBuffer insert(int offset,java.lang.String str){
  internal.insert(offset,str);
  return this;
}

public java . lang . StringBuffer insert ( int offset , java . lang . String str ) { internal . insert ( offset , str ) ; return this ; }
inserts the string into this string buffer . the characters of the string argument are inserted , in order , into this string buffer at the indicated offset , moving up any characters originally above that position and increasing the length of this string buffer by the length of the argument . if str is null , then the four characters " null " are inserted into this string buffer . the character at index k in the new character sequence is equal to : the character at index k in the old character sequence , if k is less than offset the character at index k - offset in the argument str , if k is not less than offset but is less than offset + str . length ( ) the character at index k - str . length ( ) in the old character sequence , if k is not less than offset + str . length ( ) the offset argument must be greater than or equal to 0 , and less than or equal to the length of this string buffer .
