How to merge List into a single PdfDocument

Question

I have a List with multiple PDFs , and I want to merge all of them into a single PdfDocument (im using iText) , and then transform this PdfDocument into a ByteArrayOutputStream (OR a byte[]).

public byte[] mergePdfDocumentsIntoAPdfDocument (List<PdfDocument> pdfDocuments){

 final ByteArrayOutputStream mergedPdfStream = new ByteArrayOutputStream();
    final PdfDocument mergedPdfDocument = new PdfDocument(new PdfWriter(mergedPdfStream));


//I dont know how can I continue this

What should I do in order to achieve this?

https://stackoverflow.com/questions/3585329/how-to-merge-two-pdf-files-into-one-in-java — devgianlu, Jul 13 '19 at 16:55
https://github.com/itext/i7js-samples/blob/develop/publications/book/src/test/java/com/itextpdf/samples/book/part2/chapter06/Listing_06_21_Concatenate.java — devgianlu, Jul 13 '19 at 17:00
This will probably work but how can I transform the PdfDocument into a byte [] ? — Nexussim Lements, Jul 13 '19 at 17:01

score 3 · Accepted Answer · answered Jul 13 '19 at 17:08

public byte[] mergePdfDocumentsIntoAPdfDocument(List<PdfDocument> pdfDocuments){
    ByteArrayOutputStream mergedPdfStream = new ByteArrayOutputStream();
    PdfDocument resultDoc = new PdfDocument(new PdfWriter(mergedPdfStream));

    for (PdfDocument doc : pdfDocuments) {
        int n = doc.getNumberOfPages();
        for (int i = 1; i <= n; i++) {
            PdfPage page = doc.getPage(i).copyTo(resultDoc);
            resultDoc.addPage(page);
        }
    }

    resultDoc.close();
    return mergedPdfStream.toByteArray();
}

How to merge List into a single PdfDocument

1 Answers1