Verifying unmarshalled entries from List( Jaxb)

I have a 4 XML files having a structure as follows:

<?xml version="1.0"?>
<Registry>
    <Insitutions>
        <Insitiution>
            <name>A</name>
            <location>B</location>
        </Insitiution>
        <Insitiution>
            <name>C</name>
            <location>D</location>
        </Insitiution>
        <Insitiution>
            <name>E</name>
            <location>F</location>
        </Insitiution>
    </Insitutions>
</Registry>

I have written the classes for individual XML tags, and have unmarshalled them using jaxb. I unmarshall all the files and store all the entries in a list as follows:

  private static List<String> loadBaseNodesets() throws JAXBException {
        log.info("Loading nodesets");
        Registry xmlentries = null;
        JAXBContext jaxbContext = null;
        List<Registry> entries = new ArrayList<>();
        List<String> privateBaseNodeSets= new ArrayList<>();
        File dir = new File("XMLFiles");
        if (dir.exists() && dir.isDirectory()) {
            FileFilter filter = new FileFilter() {
                public boolean accept(File file) {
                    return file.isFile() && file.getName().endsWith(".xml");
                }
            };
        log.info("iterating through all files");
        File [] files = dir.listFiles(filter);
        if (files != null) {                    
                for (int i =0;i <1;i++) {   
                    jaxbContext = JAXBContext.newInstance(Registry.class);
                    Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
                    xmlentries = (Registry) jaxbUnmarshaller.unmarshal(files[i]);
                    privateBaseNodeSets.add(xmlentries.toString());
                    log.info(files[i].getName()+" NodeSet loaded");
                    entries.add(xmlentries);            
                }
            }
        
        }       
        log.info("Nodeset loading complete");
    return privateBaseNodeSets;
  }

I need to put all the xmlentries to a list of string.

Now from the main program, I would like to check if I can get the same format of the XML entries.

 public static void main(String[] args) throws JAXBException {
    log.info("Started local test main");
    List<String> baseNodesets = loadBaseNodesets();
    ListIterator<String> litr = baseNodesets.listIterator();
    while (litr.hasNext()) {
        
        JAXBContext jaxbContext=JAXBContext.newInstance(Registry.class);
        Marshaller marshaller = jaxbContext.createMarshaller();#
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(, System.out);// DONT KNOW THE FIRST PARAMETER
        }

I am not able to get the first parameter here. Could anyone please help?

Answer

I am not sure if I understood your question correctly but I am guessing you are trying to do something like this:

  1. Read each file one by one and unmarshal and store in entries List.
  2. Then loop over the entries List and marshal them one by one.
  3. Store the converted XML into List

I stored 2 same XML files in a folder and tried to read it

XML files:

<?xml version="1.0"?>
<Registry>
    <Insitutions>
        <Insitiution>
            <name>A</name>
            <location>B</location>
        </Insitiution>
        <Insitiution>
            <name>C</name>
            <location>D</location>
        </Insitiution>
        <Insitiution>
            <name>E</name>
            <location>F</location>
        </Insitiution>
    </Insitutions>
</Registry>

Root:

@Data
@XmlRootElement(name = "Registry")
@XmlAccessorType(XmlAccessType.FIELD)
public class Root {
    @XmlElementWrapper(name = "Insitutions")
    @XmlElement(name = "Insitiution")
    private List<Insitiution> Insitiution;
}

Insitiution:

@Data
@XmlAccessorType(XmlAccessType.FIELD)
public class Insitiution {
    private String name;
    private String location;
}

Marshalling (Main):

public class Marshalling {

    public static void main(String[] args) throws JAXBException, XMLStreamException, FactoryConfigurationError, IOException, SAXException {
        final File dir = new File("/Users/Downloads/test");
        final List<Root> entries = new ArrayList<>();
        final Unmarshaller unmarshaller = JAXBContext.newInstance(com.newJAXB.Root.class).createUnmarshaller();
        final StringWriter singleXmlEvent = new StringWriter();
        final List<String> xmlOutput = new ArrayList<>();
        final Marshaller marshaller = JAXBContext.newInstance(Root.class).createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        for (File file : dir.listFiles()) {
            if (!file.isDirectory() && file.getName().endsWith(".xml")) {
                //Storing all the files into entries List
                final DataInputStream inputStream = new DataInputStream(new FileInputStream(file.getAbsolutePath()));
                final XMLStreamReader xmlStreamReader = XMLInputFactory.newInstance().createXMLStreamReader(inputStream);
                final com.newJAXB.Root root = unmarshaller.unmarshal(xmlStreamReader, com.newJAXB.Root.class).getValue();
                entries.add(root);
                System.out.println(root.toString());
            }
        }

        //Loop through each entry in entries and marshal it
        for (Root item : entries) {
            marshaller.marshal(item, singleXmlEvent);
            xmlOutput.add(singleXmlEvent.toString());
            // Clear the StringWriter for next event
            singleXmlEvent.getBuffer().setLength(0);
        }

        //Final all the XML
        System.out.println(xmlOutput);
    }
}

Output:

Root(Insitiution=[Insitiution(name=A, location=B), Insitiution(name=C, location=D), Insitiution(name=E, location=F)])
Root(Insitiution=[Insitiution(name=A, location=B), Insitiution(name=C, location=D), Insitiution(name=E, location=F)])
[<?xml version="1.0" encoding="UTF-8"?>
<Registry>
   <Insitutions>
      <Insitiution>
         <name>A</name>
         <location>B</location>
      </Insitiution>
      <Insitiution>
         <name>C</name>
         <location>D</location>
      </Insitiution>
      <Insitiution>
         <name>E</name>
         <location>F</location>
      </Insitiution>
   </Insitutions>
</Registry>
, <?xml version="1.0" encoding="UTF-8"?>
<Registry>
   <Insitutions>
      <Insitiution>
         <name>A</name>
         <location>B</location>
      </Insitiution>
      <Insitiution>
         <name>C</name>
         <location>D</location>
      </Insitiution>
      <Insitiution>
         <name>E</name>
         <location>F</location>
      </Insitiution>
   </Insitutions>
</Registry>
]