使用 STAX JAVA 在 XML 中读取 Element 的多个子项

Question

How do I read all childrem of Item element and store the in an object

This is my sample xml file

<People>
  <Person>
    <Name>Ben</Name>
    <Items>
      <Item>Pen</Item>
      <Item>Paper</Item>
      <Item>Books</Item>
    </Items>
  </Person>
  <Person>
    <Name>Alex</Name>
    <Items>
      <Item>Pencil</Item>
      <Item>Eraser</Item>
    </Items>
</People>

I made a Person object with getters and setters

public class Person{ // SAMPLE OBJECT
    private String name; @getters and setters 
    private String item; @getters and setters
}

This is my method where it read

  public ArrayList<Person> getPeople(){

        people = new ArrayList<>();        
        Person a = null;        
        if (Files.exists(peoplePath))  // prevent the FileNotFoundException
        {
            // create the XMLInputFactory object
            XMLInputFactory inputFactory = XMLInputFactory.newFactory();
            try
            {
                // create a XMLStreamReader object
                FileReader fileReader =
                    new FileReader(peoplePath.toFile());
                XMLStreamReader reader =
                    inputFactory.createXMLStreamReader(fileReader);

                // read from the file
                while (reader.hasNext())
                {
                    int eventType = reader.getEventType();
                    switch (eventType)
                    {
                        case XMLStreamConstants.START_ELEMENT:
                            String elementName = reader.getLocalName();
                            if (elementName.equals("Person"))
                            {
                                a = new Person();
                            }
                            if (elementName.equals("Name"))
                            {
                                String name = reader.getElementText();
                                a.setName(name);                
                             }
                            
                            if (elementName.equals("Item"))
                            {
                                String item= reader.getElementText();
                                a.setItem(item);
                            }
                            break;
                        case XMLStreamConstants.END_ELEMENT:
                            elementName = reader.getLocalName();
                            if (elementName.equals("Person"))
                            {
                                people.add(a);
                            }
                            break;
                        default:
                            break;
                    }
                    reader.next();
                }
            }
            catch (IOException | XMLStreamException e)
            {
                System.out.println(e);
                return null;
            }
        }
        return people;
    }

This method displays
Ben
Alex

but if I get the items it only using similar code, it displays
Books
Eraser

    public static void displayPeople(){
     
        ArrayList<Person> people = personDAO.getPeople();
        People p = null;
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < people.size(); i++)
        {
            a = people.get(i);
            sb.append(a.getName());          
            sb.append("\n");
        }
        System.out.println(sb.toString());
    }

I wanted to do this output

Ben
    Pen
    Paper
    Book
Alex
    Pencil 
    Eraser

Answer 1

First, your xml is missing the Person element closing just before the end.

</Person>

Second, your Person class is not really correct. Items should be a list of String instead of just a String.

public class Person {
// private keyword is removed for brevity
    String name; 
    List<String> items = new ArrayList<>(); 
}

Third, your code needs to be updated to use the list of items as follows:

if (elementName.equals("Item"))
{
    String item= reader.getElementText();
    a.getItems().add(item);
}

I'm actually wondering: Why do you choose Stax instead of JAXB? Your XML schema is actually quite straight-forward to be handled with JAXB. And there will be very little boilerplate code for the conversion of XML to Java object, which means your code will be more readable and maintainable with JAXB. Just my 2 cents.