Merge PDF Files in Java

In this article, I will introduce two methods to merge PDF files in Java application.

1. Merge PDF files into a single file

2. Merge a specific page or a page range of a PDF file into another PDF file

The below examples use Free Spire.PDF for Java library.

Imported NameSpace:

import com.spire.pdf.PdfDocument;
import com.spire.pdf.PdfDocumentBase;

Merge PDF files into a single file

String[] files = new String[] { "file1.pdf", "file2.pdf"};
//load PDF files
PdfDocumentBase pdf = PdfDocument.mergeFiles(files);

//merge into a single file
pdf.save("MergeFiles.pdf");

Merge a specific page or a page range of a PDF file into another PDF file

String[] files = new String[]
        {
                "file1.pdf",
                "file2.pdf",
        };

//create a PdfDocument[]
PdfDocument[] pdfs = new PdfDocument[files.length];
PdfDocument pdf = new PdfDocument();
for (int i = 0; i < files.length; i++) {

     //load the PDF files
    pdfs[i] = new PdfDocument();
    pdfs[i].loadFromFile(files[i]);

}

//merge the first page of file2.pdf into file1.pdf
//pdfs[0].insertPage(pdfs[1], 0); 

//merge page range 1-2 of file2.pdf into file1.pdf
pdfs[0].insertPageRange(pdfs[1], 0, 1);

//save the resultant file
pdfs[0].saveToFile("MergePages.pdf");
pdf.close();