I have the sample Java code which is being used along with apache PDFBox library.

The temp files to created in place of taking the actual files in the following code.

import org.apache.pdfbox.multipdf.PDFMergerUtility;
import org.apache.pdfbox.pdmodel.PDDocument;
  
import java.io.File; 
import java.io.IOException;

public class MergePDFs {
   public static void main(String[] args) throws IOException {

      //Loading an existing PDF document
      File file1 = new File("C:/PdfBox_Examples/sample1.pdf");
      PDDocument doc1 = PDDocument.load(file1);
       
      File file2 = new File("C:/PdfBox_Examples/sample2.pdf");
      PDDocument doc2 = PDDocument.load(file2);
         
      //Instantiating PDFMergerUtility class
      PDFMergerUtility PDFmerger = new PDFMergerUtility();

      //Setting the destination file
      PDFmerger.setDestinationFileName("C:/PdfBox_Examples/merged.pdf");

      //adding the source files
      PDFmerger.addSource(file1);
      PDFmerger.addSource(file2);

      //Merging the two documents
      PDFmerger.mergeDocuments();

      System.out.println("Documents merged");
      //Closing the documents
      doc1.close();
      doc2.close();
   }

}

Hi Krishna,

You can refer to below articles, which will help you.

https://community.pega.com/support/support-articles/merging-two-pdf-documents

https://community.pega.com/support/support-articles/using-itext-merging-two-pdf

https://community.pega.com/support/support-articles/can-we-merge-multiple-documents-word-excel-and-generate-pdf