code: public void rotate180() {
      int width = getWidth();
      int height = getHeight();
      BitArray topRow = new BitArray(width);
      BitArray bottomRow = new BitArray(width);
      for (int i = 0; i < (height + 1) / 2; i++) {
        topRow = getRow(i, topRow);
        bottomRow = getRow(height - 1 - i, bottomRow);
        topRow.reverse();
        bottomRow.reverse();
        setRow(i, bottomRow);
        setRow(height - 1 - i, topRow);
      }
    }
docs: Modifies this {@code BitMatrix} to represent the same but rotated 180 degrees