Question

I have an object config which has some properties. I can export this ok, however, it also has an ArrayList which relates to embedded classes which I can’t get to appear when I export to XML. Any pointers would be helpful.

Export Method

public String exportXML(config conf, String path) {
    String success = "";
    try {
        FileOutputStream fstream = new FileOutputStream(path);
        try {
            XMLEncoder ostream = new XMLEncoder(fstream);
            try {
                ostream.writeObject(conf);
                ostream.flush();
            } finally {
                ostream.close();
            }
        } finally {
            fstream.close();
        }
    } catch (Exception ex) {
        success = ex.getLocalizedMessage();
    }
    return success;
}

Config Class (some detail stripped to keep size down)

public class config {

protected String author = "";
protected String website = "";
private ArrayList questions = new ArrayList();

public config(){
}

public void addQuestion(String name) {
    questions.add(new question(questions.size(), name));
}

public void removeQuestion(int id) {
    questions.remove(id);
    for (int c = 0; c <= questions.size(); c++) {
        question q = (question) (questions.get(id));
        q.setId(c);
    }
    questions.trimToSize();
}

public config.question getQuestion(int id){
    return (question)questions.get(id);
}


/**
 * There can be multiple questions per config.
 * Questions store all the information regarding what questions are
 * asked of the user, including images, descriptions, and answers.
 */
public class question {

    protected int id;
    protected String title;
    protected ArrayList answers;

    public question(int id, String title) {
        this.id = id;
        this.title = title;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void addAnswer(String name) {
        answers.add(new answer(answers.size(), name));
    }

    public void removeAnswer(int id) {
        answers.remove(id);
        for (int c = 0; c <= answers.size(); c++) {
            answer a = (answer) (answers.get(id));
            a.setId(c);
        }
        answers.trimToSize();
    }

    public config.question.answer getAnswer(int id){
        return (answer)answers.get(id);
    }

    public class answer {

        protected int id;
        protected String title;

        public answer(int id, String title) {
            this.id = id;
            this.title = title;
        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }
    }
}

}

Resultant XML File

<?xml version="1.0" encoding="UTF-8"?> 
<java version="1.6.0_18" class="java.beans.XMLDecoder"> 
 <object class="libConfig.config"> 
  <void property="appName"> 
   <string>xxx</string> 
  </void> 
  <void property="author"> 
   <string>Andy</string> 
  </void> 
  <void property="website"> 
   <string>www.example.com/dsx.xml</string> 
  </void> 
 </object> 
</java> 

Answer 1

Xstream deals with this much better, from their description:

• Requires no modifications to objects.
• Serializes internal fields, including private and final.
• Supports non-public and inner classes.
• Classes are not required to have default constructor.