public StrBuilder insert(int index,char chars[]){
  validateIndex(index);
  if (chars == null) {
    return insert(index,nullText);
  }
  int len=chars.length;
  if (len > 0) {
    ensureCapacity(size + len);
    System.arraycopy(buffer,index,buffer,index + len,size - index);
    System.arraycopy(chars,0,buffer,index,len);
    size+=len;
  }
  return this;
}

public StrBuilder insert ( int index , char chars [ ] ) { validateIndex ( index ) ; if ( chars == null ) { return insert ( index , nullText ) ; } int len = chars . length ; if ( len > 0 ) { ensureCapacity ( size + len ) ; System . arraycopy ( buffer , index , buffer , index + len , size - index ) ; System . arraycopy ( chars , 0 , buffer , index , len ) ; size += len ; } return this ; }
inserts the character array into this builder . inserting null will use the stored null text value .
