Jackson List Help - Java

Question

I am trying to create some xml with Jackson and I cannot get the list to display like I need. I am getting:

<Messages>
  <Messages>...</Messages>
  <Messages>...</Messages>
</Messages>

I want it to look like:

<Messages>
  <Message>...</Message>
  <Message>...</Message>
</Messages>

My code looks like this:

  public List<Message> messages;

Whatever I name that variable, is the same name all of the child elements get. I am sure this has been answered elsewhere, but I cannot find anything that will take care of my issue. Thanks for the help.

Answer 1

I found the easy way to do this without adding more dependencies. You just use the annotations:

@JacksonXmlElementWrapper(localName = "Messages")
@JacksonXmlProperty(localName = "Message")

This question is what pointed me in the right direction. Jackson XML globally set element name for container types . You can also read about this annotation on the github page here

Answer 2

Try JAXB Annotations like this:

 @XmlElementWrapper(name = "Messages")
  // XmlElement sets the name of the entities
  @XmlElement(name = "Message")
  public List<Message> messages;

See http://wiki.fasterxml.com/JacksonJAXBAnnotations for using JAXB annotations with Jackson.

There's a good JAXB tutorial here:

http://www.vogella.com/articles/JAXB/article.html

and here:

https://jaxb.java.net/tutorial/index.html

Answer 3

This works perfectly fine for List of Strings.

XML

<Messages>
     <Message>msg1</Message>
     <Message>msg2</Message>
     <Message>msg3</Message>
</Messages>

Jackson Code

@JacksonXmlElementWrapper(localName = "Messages")
@JacksonXmlProperty(localName = "Message")
public List<String> messages;

Answer 4

You could also try using:

@JacksonXmlRootElement(localName = "Messages")
class Messages{
    @JacksonXmlProperty(localName = "Message")
    List<String> message = new ArrayList<>();

    public List<String> getMessage() {
        return message;
    }

    public void setMessage(String message) {
       this.message.add(message);
    }
}

Answer 5

As another option you can do it without annotations by changing the XML. You would change the XML to,

<messages>
  <Message>
    <value>"foo"</value>
  </Message>
  <Message>
    <value>"bar"</value>
  </Message>
</messages>

and change the Java to

class Foobar {
  List<Message> messages;
}
class Message {
  String value;
}

Then Messages would contain two objects of the Message class, one where the value member equals "foo" and the other where the value member equals "bar".