To rotate a page in a PDF document.

PDFDoc doc = new PDFDoc(filename);

// Rotate the first page 90 degrees clockwise.
Page page = doc.getPage(1);
int originalRotation = page.getRotation();
int rotation;
switch (originalRotation)
{
  case Page.e_0:   rotation = Page.e_90;  break;
  case Page.e_90:  rotation = Page.e_180; break;
  case Page.e_180: rotation = Page.e_270; break;
  case Page.e_270: rotation = Page.e_0;   break;
  default:         rotation = Page.e_0;   break;
}
page.setRotation(rotation);

A page can be rotated clockwise, by 90 degrees, when displayed or printed. The Page.GetRotation() method returns the Page.Rotate enum specifying the current rotation. Similarly, Page.SetRotation() sets the current rotation.