Content Comparison 
The steps to perform a content comparison are as follows:
- Open the two documents being compared. 
- Create the CPDFCompare object. 
- Set the colour and other properties of the comparison. 
- Call compare.doCompare() to get the comparison results and save them to the document using the generateNewDoc() method. 
This example shows how to add an content comparison:
Java
CPDFDocument baseDocument = new CPDFDocument();
baseDocument.open(rootDir + "/TestFiles/comparefile.pdf");
CPDFDocument comDocument = new CPDFDocument();
comDocument.open(rootDir + "/TestFiles/comparefile1.pdf");
printDividingLine();
CPDFCompare compare = baseDocument.createCompare(baseDocument, comDocument);
compare.setReplaceResColor(Color.decode("#93B9FD").getRGB());
compare.setInsertResColor(Color.decode("#C0FFEC").getRGB());
CPDFCompareResults result = compare.doCompare(0, 0, CPDFCompare.CompType.COMPAREALL.id, true);
compare.generateNewDoc(rootDir + "/out/compareTest.pdf");