pdfbox message "You did not close a PDF Document"

Question

I have the java code that takes pdf files from a directory copy pages to new pdfs and then saves it to anoter location. But it throws:

org.apache.pdfbox.cos.COSDocument finalize WARNING: Warning: You did not close a PDF Document

but I did close the pdf!!!

import org.apache.pdfbox.multipdf.Splitter;
import org.apache.pdfbox.pdmodel.PDDocument;

import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;

public class Test {
    public static void main(String[] args) throws IOException{
        File srcFolder = new File(System.getProperty("user.dir") + "\\source");
        File[] srcFiles = srcFolder.listFiles();
        Arrays.sort(srcFiles);
        for (File srcFile : srcFiles) {
            PDDocument srcPDDocument = PDDocument.load(srcFile);
            PDDocument destPDDOcument = new PDDocument();
            
            Splitter splitting = new Splitter();
            
            List<PDDocument> pages = splitting.split(srcPDDocument);
            for (PDDocument page : pages) {
                destPDDOcument.addPage(page.getPage(0));
            }
            String dest = System.getProperty("user.dir") + "\\dest\\" + srcFile.getName();
            destPDDOcument.save(dest);
            destPDDOcument.close();
            srcPDDocument.close();
            System.out.println(srcFile.getName());
        }
    }
}

Answer 1

You need to close the intermediate documents you get from the splitter (that are confusingly named pages). Do this AFTER saving destPDDOcument. So add code like this:

for (PDDocument doc : pages)
{
    doc.close();
}