public void ensureCapacity(int minimumCapacity){
  internal.ensureCapacity(minimumCapacity);
}

public void ensureCapacity ( int minimumCapacity ) { internal . ensureCapacity ( minimumCapacity ) ; }
ensures that the capacity of the buffer is at least equal to the specified minimum . if the current capacity of this string buffer is less than the argument , then a new internal buffer is allocated with greater capacity . the new capacity is the larger of : the minimumcapacity argument . twice the old capacity , plus 2 . if the minimumcapacity argument is nonpositive , this method takes no action and simply returns .
