Document document = new Document();
document.loadFromFile("input.docx");
document.saveToFile("output.ofd", FileFormat.OFD);

Document doc = new Document();
doc.loadFromFile(inputFile);
doc.setTrackChanges(true);
TextRange range = doc.getLastParagraph().appendText("123413");
range.getInsertRevision().setAuthor("user");
doc.saveToFile(outputFile);
doc.dispose(); 

Document.compare(Document document, String author, CompareOptions options);
Document.compare(Document document, String author, Date date, CompareOptions options);
CompareOptions.setIgnoreFormatting(true); 

//The fourth parameter controls whether the text is wrapped
doc.getConvertOptions().setPdfToXlsxOptions(new XlsxLineLayoutOptions(false, false, false, false));

PdfToLinearizedPdfConverter converter = new PdfToLinearizedPdfConverter(inputPath);
converter.toLinearizedPdf(OutputPath); 

Presentation ppt = new Presentation();
ppt.loadFromFile("input.pptx");
String latexMathCode = "x^{2}+\\sqrt{x^{2}+1}=2";
IAutoShape shape = ppt.getSlides().get(0).getShapes().appendShape(ShapeType.RECTANGLE, new Rectangle2D.Float(30, 100, 400, 30));
shape.getTextFrame().getParagraphs().clear();

//Add math equation
ParagraphEx tp = shape.getTextFrame().getParagraphs().addParagraphFromLatexMathCode(latexMathCode);for (int i = 0; i<ppt.getSlides().get(0).getShapes().getCount(); i++)
{
    //Check whether shape contains math equations
    boolean containMathEquation = ((IAutoShape)ppt.getSlides().get(0).getShapes().get(i)).isContainMathEquation();
}
ppt.saveToFile("output.pptx", FileFormat.PPTX_2013);
ppt.dispose();

Workbook workbook = new Workbook();
workbook.loadFromFile("input.xlsx");
workbook.saveToFile("output.ofd", FileFormat.OFD); 

Workbook workbook = new Workbook();
workbook.loadFromFile(inputFile);
Worksheet sheet = workbook.getWorksheets().get(0);
//Select data range
CellRange range = sheet.getRange().get("A1:B18");
//Subtotal selected data
sheet.subtotal(range, 0, new int[] { 1 }, SubtotalTypes.Sum, true, false, true);
//Save to file.
workbook.saveToFile(outputFile, ExcelVersion.Version2010);
workbook.dispose();