This example shows how to create a document using the Apache PDFBox library. The first page contains text in various styles, fonts and colors. The second page adds an image, draws a couple of lines, and a colored rectangle. While PDFBox can do many things with an existing PDF, its API is somewhat low-level. For example, it's not easily possible to add underline or strikethrough effects to text.
To get started, download the latest pdfbox-app-X.Y.Z.jar file; it contains everything in one convenient file.
The same code example for iText 2 (and its API-compatible replacement OpenPDF) and iText 5 can be found here.