PDF merging implementation

Question

How can this be improved?

/*
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 * and open the template in the editor.
 */
package pdf_merging_70112016;
import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.pdf.PdfContentByte;
import com.lowagie.text.pdf.PdfImportedPage;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import properties.ApplicationProperties;
/**
 *
 * @author
 */
public class PDFMerging {
 public void mergePDF() throws FileNotFoundException {
 ApplicationProperties prop = ApplicationProperties.getInstance();
 prop.loadProperties();
 String temppath = prop.getClickProperty("tempPath");
 String FAQPath = prop.getClickProperty("FAQPath");
 String finalPDFParh = prop.getClickProperty("finalPath");
 String errorPath = prop.getClickProperty("errorPath");
 String outputFilename = "";
 File tempFolder = new File(temppath);
 File FAQFolder = new File(FAQPath);
 File[] listOfTempFiles = tempFolder.listFiles();
 File[] listOfFAQFiles = FAQFolder.listFiles();
 for (int i = 0; i < listOfTempFiles.length; i++) {
 for (int j = 0; j < listOfFAQFiles.length; j++) {
 if (listOfTempFiles[i].isFile() && listOfTempFiles[i].length() > 0) {
 if (listOfTempFiles[i].getName().toLowerCase().contains(".pdf")) {
 if (listOfTempFiles[i].getName().substring(listOfTempFiles[i].getName().lastIndexOf("#") + 1).equals(listOfFAQFiles[j].getName())) {
 try {
 List<InputStream> list = new ArrayList<InputStream>();
 list.add(new FileInputStream(listOfTempFiles[i]));
 list.add(new FileInputStream(listOfFAQFiles[j]));
 System.out.println(listOfTempFiles[i].getName() + "with FAQ: " + listOfFAQFiles[j].getName());
 int iend = listOfTempFiles[i].getName().lastIndexOf("#");
 if (iend != -1) {
 outputFilename = listOfTempFiles[i].getName().substring(0, iend);
 }
 OutputStream out = new FileOutputStream(new File(finalPDFParh + "/" + outputFilename + ".pdf"));
 doMerge(list, out);
 list.clear();
 } catch (FileNotFoundException e) {
 e.printStackTrace();
 } catch (DocumentException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
 if (listOfTempFiles[i].getName().substring(listOfTempFiles[i].getName().lastIndexOf("#") + 1).toUpperCase().contains("NA")) {
 int iend = listOfTempFiles[i].getName().lastIndexOf("#");
 if (iend != -1) {
 outputFilename = listOfTempFiles[i].getName().substring(0, iend);
 }
 listOfTempFiles[i].renameTo(new File(finalPDFParh + "/" + outputFilename + ".pdf"));
 }
 }
 } else {
 listOfTempFiles[i].renameTo(new File(errorPath + "/" + outputFilename + ".pdf"));
 }
 }
 }
 }
 public static void doMerge(List<InputStream> list, OutputStream outputStream)
 throws DocumentException, IOException {
 Document document = new Document();
 PdfWriter writer = PdfWriter.getInstance(document, outputStream);
 document.open();
 PdfContentByte cb = writer.getDirectContent();
 for (InputStream in : list) {
 PdfReader reader = new PdfReader(in);
 for (int i = 1; i <= reader.getNumberOfPages(); i++) {
 document.newPage();
 //import the page from source pdf
 PdfImportedPage page = writer.getImportedPage(reader, i);
 //add the page to the destination pdf
 cb.addTemplate(page, 0, 0);
 }
 }
 outputStream.flush();
 document.close();
 outputStream.close();
 }
}

• Heslacher: I have rolled back the last edit. Please see what you may and may not do after receiving answers .

Answer 1

• Remove the automatically generated comment at the top of the file.
• Instead of using printStackTrace, either throw the exception or log the (expected) exception and continue.
• Any file you open must be closed again. Use try-with-resources for that.
• list.clear() is unnecessary. Just let the garbage collector do its work.
• Use for (File faqFile : faqFiles) instead of counting j.
• Since listOfFAQFiles is not a list but an array, don't call it list. Just faqFiles is simpler and enough.
• Instead of passing open streams around, prefer to pass the files. This makes it easier to close the streams, even when an exception occurs.