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Parsing an XML tag with colon in java jaxb

<?xml version="1.0" encoding="UTF-8"?>
<REQ-IF xmlns="http://www.omg.org/spec/ReqIF/20110401/reqif.xsd" xmlns:reqif-xhtml="http://www.w3.org/1999/xhtml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<THE-VALUE>
<reqif-xhtml:div>Hello</reqif-xhtml:div>
</THE-VALUE>
</REQ-IF>
I need to get the "Hello" message. While parsing this xml I am getting null value,
I have tried multiple thing, but issue did not resolve. My question is how to parse such tags with colon (namespaces).
public static void main(String[] args) {
InputStream is = new FileInputStream(file);
JAXBContext jaxbContext = JAXBContext.newInstance(REQ_IF.class);
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
REQ_IF req_if = (REQ_IF) jaxbUnmarshaller.unmarshal(is);
THE_VALUE the_value = req_if.getThe_value();
DIV div = the_value.getDiv();
String value = div.getValue();
System.out.println(value);
}
I have created three classes.
First is REQ_IF
#XmlRootElement(name="REQ-IF")
#XmlAccessorType(XmlAccessType.FIELD)
public class REQ_IF implements Serializable {
private static final long serialVersionUID = 1L;
#XmlElement(name="THE-VALUE")
THE_VALUE the_value;
public REQ_IF() {
super();
}
public REQ_IF(THE_VALUE the_value) {
super();
this.the_value = the_value;
}
public THE_VALUE getThe_value() {
return the_value;
}
public void setThe_value(THE_VALUE the_value) {
this.the_value = the_value;
}
}
Second is THE_VALUE
#XmlRootElement(name="THE-VALUE")
#XmlAccessorType(XmlAccessType.FIELD)
public class THE_VALUE implements Serializable {
private static final long serialVersionUID = 1L;
#XmlElement(name="div")
DIV div;
public THE_VALUE() {
super();
}
public THE_VALUE(DIV div) {
super();
this.div = div;
}
public DIV getDiv() {
return div;
}
public void setDiv(DIV div) {
this.div = div;
}
}
And third one is DIV
#XmlRootElement(name = "div", namespace = "http://www.w3.org/1999/xhtml")
#XmlAccessorType(XmlAccessType.NONE)
public class DIV implements Serializable {
private static final long serialVersionUID = 1L;
#XmlValue
String value;
public DIV() {
super();
}
public DIV(String value) {
super();
this.value = value;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
Here is my package-info.java
#javax.xml.bind.annotation.XmlSchema(
namespace = "http://www.omg.org/spec/ReqIF/20110401/reqif.xsd",
elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED,
xmlns = {
#javax.xml.bind.annotation.XmlNs(prefix = "", namespaceURI = "http://www.omg.org/spec/ReqIF/20110401/reqif.xsd"),
#javax.xml.bind.annotation.XmlNs(prefix = "reqif-xhtml", namespaceURI = "http://www.w3.org/1999/xhtml")
}
)
package com.abc.xyz;

why JAXB java xml unmarshaller return null

I am trying to unmarshal XML to java class as follows:-
My xml file as follows:-
<Features_res>
<StartWeek>202017</StartWeek>
<EndWeek>202035</EndWeek>
<Pno12>ABCDEEB</Pno12>
<FeatureList>
<Feature>
<Code>T002</Code>
</Feature>
<Feature>
<Code>T002</Code>
</Feature>
</FeatureList>
</Features_res>
Java InteriorResponse:-
#XmlRootElement(name = "Features_res")
public class InteriorResponse {
#XmlElement(name = "StartWeek")
private int sWeek;
#XmlElement(name = "EndWeek")
private int eWeek;
#XmlElement(name = "Pno12")
private String p12;
List<Feature> featureList;
public InteriorResponse() {
}
public InteriorResponse(int startWeek, int endWeek, String pno12) {
super();
this.sWeek = startWeek;
this.eWeek = endWeek;
this.p12 = pno12;
}
public int getStartWeek() {
return sWeek;
}
public void setStartWeek(int startWeek) {
this.sWeek = startWeek;
}
public int getEndWeek() {
return eWeek;
}
public void setEndWeek(int endWeek) {
this.eWeek = endWeek;
}
public String getPno12() {
return p12;
}
public void setPno12(String pno12) {
this.p12 = pno12;
}
public List<Feature> getFeatureList() {
return featureList;
}
#XmlElement(name = "FeatureList")
public void setFeatureList(List<Feature> featureList) {
this.featureList = featureList;
}
}
Another Java Feature:-
#XmlRootElement(name = "Feature")
public class Feature {
//#XmlElement(name = "Feature")
private String feature_;
#XmlElement(name = "code")
private String code_;
public String getCode() {
return code_;
}
public void setCode(String code) {
this.code_ = code;
}
public String getFeature_() {
return feature_;
}
public void setFeature_(String feature_) {
this.feature_ = feature_;
}
}
I am using above class as :-
public static void xmlToInterior() {
File file = new File("minxml.xml");
JAXBContext jaxbContext;
try {
jaxbContext = JAXBContext.newInstance(InteriorResponse.class);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
InteriorResponse interiorFeatures = (InteriorResponse) unmarshaller.unmarshal(file);
List<Feature> list_feat = interiorFeatures.getFeatureList();
for(Feature ft : list_feat) {
System.out.println(ft.getCode());
}
} catch (JAXBException e) {
e.printStackTrace();
}
}
Output I have as:-
list_feat
code_ null
feature_ null
And list_feat has size 1. It should 2.
Also I have to name class member sWeek instead of startWeek. Otherwise, jaxbContext = JAXBContext.newInstance(InteriorResponse.class) throws exception like 2 element exist with same name.
XML additional part
I thought I could do the reaming part of the XML. I was trying part by part. But I couldn't do it. I really need to find some good tutorial or book about JXB. All I find a short overview of JXB. Any suggestion about where to read in details?
<Features_res>
<StartWeek>202017</StartWeek>
<EndWeek>202035</EndWeek>
<Pno12>ABCDEEB</Pno12>
<FeatureList>
<Feature>
<Code>T002</Code>
</Feature>
<Feature>
<Code>T002</Code>
</Feature>
</FeatureList>
<OptionList>
<Option>001048</Option>
<Option>000050</Option>
<Option>000790</Option>
</OptionList>
</Features_res>
So I made new class as:-
public class OptionList {
private List<Option> options;
#XmlElement(name = "Option")
public List<Option> getOptions() {
return options;
}
public void setOptions(List<Option> options) {
this.options = options;
}
}
Another class as :-
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlTransient;
public class Option {
#XmlElement(name = "Option")
private String option_;
public String getOption() {
return option_;
}
public void setOption(String option) {
this.option_ = option;
}
}
And updated for InteriorResponse class as:-
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement(name = "Features_res")
public class InteriorResponse {
#XmlElement(name = "StartWeek")
private int sWeek;
#XmlElement(name = "EndWeek")
private int eWeek;
#XmlElement(name = "Pno12")
private String p12;
private FeatureList featureList;
private OptionList optionList;
public InteriorResponse() {}
public InteriorResponse(int startWeek, int endWeek, String pno12) {
super();
this.sWeek = startWeek;
this.eWeek = endWeek;
this.p12 = pno12;
}
public int getStartWeek() {
return sWeek;
}
public void setStartWeek(int startWeek) {
this.sWeek = startWeek;
}
public int getEndWeek() {
return eWeek;
}
public void setEndWeek(int endWeek) {
this.eWeek = endWeek;
}
public String getPno12() {
return p12;
}
public void setPno12(String pno12) {
this.p12 = pno12;
}
#XmlElement(name = "FeatureList")
public FeatureList getFeatureList() {
return featureList;
}
public void setFeatureList(FeatureList featureList) {
this.featureList = featureList;
}
#XmlElement(name = "OptionList")
public OptionList getOptionList() {
return optionList;
}
public void setOptionList(OptionList optionList) {
this.optionList = optionList;
}
#Override
public String toString() {
return "InteriorResponse{"
+ "sWeek="
+ sWeek
+ ", eWeek="
+ eWeek
+ ", p12='"
+ p12
+ '\''
+ ", featureList="
+ featureList
+ '}';
}
}
I couldn't get the Option.
option null
The total xml is really huge. I still would like to try the remaing parts by myself part by part.

You need to design your classes according to XML structure. Find below the classes.
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement(name = "Features_res")
public class InteriorResponse {
#XmlElement(name = "StartWeek")
private int sWeek;
#XmlElement(name = "EndWeek")
private int eWeek;
#XmlElement(name = "Pno12")
private String p12;
private FeatureList featureList;
private OptionList optionList;
public InteriorResponse() {}
public InteriorResponse(int startWeek, int endWeek, String pno12) {
super();
this.sWeek = startWeek;
this.eWeek = endWeek;
this.p12 = pno12;
}
public int getStartWeek() {
return sWeek;
}
public void setStartWeek(int startWeek) {
this.sWeek = startWeek;
}
public int getEndWeek() {
return eWeek;
}
public void setEndWeek(int endWeek) {
this.eWeek = endWeek;
}
public String getPno12() {
return p12;
}
public void setPno12(String pno12) {
this.p12 = pno12;
}
#XmlElement(name = "FeatureList")
public FeatureList getFeatureList() {
return featureList;
}
public void setFeatureList(FeatureList featureList) {
this.featureList = featureList;
}
#XmlElement(name = "OptionList")
public OptionList getOptionList() {
return optionList;
}
public void setOptionList(OptionList optionList) {
this.optionList = optionList;
}
#Override
public String toString() {
return "InteriorResponse{"
+ "sWeek="
+ sWeek
+ ", eWeek="
+ eWeek
+ ", p12='"
+ p12
+ '\''
+ ", featureList="
+ featureList
+ ", optionList="
+ optionList
+ '}';
}
}
Class for Feature object
import javax.xml.bind.annotation.XmlElement;
public class Feature {
#XmlElement(name = "Code")
private String code_;
public String getCode() {
return code_;
}
public void setCode(String code) {
this.code_ = code;
}
#Override
public String toString() {
return "Feature{" + "code_='" + code_ + '\'' + '}';
}
}
Class for FeatureList
import javax.xml.bind.annotation.XmlElement;
import java.util.List;
public class FeatureList {
private List<Feature> features;
#XmlElement(name = "Feature")
public List<Feature> getFeatures() {
return features;
}
public void setFeatures(List<Feature> features) {
this.features = features;
}
}
Class for OptionList
import javax.xml.bind.annotation.XmlElement;
import java.util.List;
public class OptionList {
private List<String> option;
#XmlElement(name = "Option")
public List<String> getOption() {
return option;
}
public void setOption(List<String> option) {
this.option = option;
}
}
For testing and simplicity, I have written a small java test program below.
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import java.io.File;
import java.util.List;
public class Test {
public static void main(String[] args) {
File file =
new File("E:\\so\\xml\\minxml.xml");
JAXBContext jaxbContext;
try {
jaxbContext = JAXBContext.newInstance(InteriorResponse.class);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
InteriorResponse interiorFeatures = (InteriorResponse) unmarshaller.unmarshal(file);
List<Feature> list_feat = interiorFeatures.getFeatureList().getFeatures();
List<String> optionList = interiorFeatures.getOptionList().getOption();
for (String option : optionList) {
System.out.println("Option Value : " + option);
}
for (Feature ft : list_feat) {
System.out.println(ft.getCode());
}
} catch (JAXBException e) {
e.printStackTrace();
}
}
}
I also provide the sample xml structure below.
<Features_res>
<StartWeek>202017</StartWeek>
<EndWeek>202035</EndWeek>
<Pno12>ABCDEEB</Pno12>
<FeatureList>
<Feature>
<Code>T002</Code>
</Feature>
<Feature>
<Code>T002</Code>
</Feature>
</FeatureList>
<OptionList>
<Option>001048</Option>
<Option>000050</Option>
<Option>000790</Option>
</OptionList>
</Features_res>

I knew very little about JAXB stuff. I have learned a lot from Sambit who helped a lot and gave me the way to start with this JAXB. Later I have implemented my version with less number of Java class and more smart use of JAXB annotations.
My version of InteriorResponse class:-
import java.util.List;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementWrapper;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlTransient;
#XmlRootElement(name = "Features_res")
public class InteriorResponse {
#XmlElement(name = "StartWeek")
private int startWeek;
#XmlElement(name = "EndWeek")
private int endWeek;
#XmlElement(name = "Pno12")
private String pno12;
#XmlElementWrapper(name = "FeatureList")
#XmlElement(name = "Feature")
private List<Feature> featureList;
#XmlElementWrapper(name = "OptionList")
#XmlElement(name = "Option")
private List<String> optionList;
public InteriorResponse() {
}
public InteriorResponse(int startWeek, int endWeek, String pno12) {
super();
this.startWeek = startWeek;
this.endWeek = endWeek;
this.pno12 = pno12;
}
#XmlTransient
public int getStartWeek() {
return startWeek;
}
public void setStartWeek(int startWeek) {
this.startWeek = startWeek;
}
#XmlTransient
public int getEndWeek() {
return endWeek;
}
public void setEndWeek(int endWeek) {
this.endWeek = endWeek;
}
#XmlTransient
public String getPno12() {
return pno12;
}
public void setPno12(String pno12) {
this.pno12 = pno12;
}
#XmlTransient
public List<Feature> getFeatureList() {
return featureList;
}
public void setFeatureList(List<Feature> featureList) {
this.featureList = featureList;
}
#XmlTransient
public List<String> getOptionList() {
return optionList;
}
public void setOptionList(List<String> optionList) {
this.optionList = optionList;
}
#Override
public String toString() {
return "InteriorResponse{" + "sWeek=" + startWeek + ", eWeek=" + endWeek + ", pno12='" + pno12 + '\'' + ", featureList=" + featureList + ", optionList="
+ optionList + '}';
}
}
My version of Feature class:-
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlTransient;
public class Feature {
#XmlElement(name = "Code")
private String code;
#XmlTransient
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
#Override
public String toString() {
return "Feature{" + "code_='" + code + '\'' + '}';
}
}
Note that I don't need any extra wrapper class for FeatuerList and OptionList. It can be done by the JAXB annotation #XmlElementWrapper(name = "FeatureList"). Also, a very important lesson learned. We have to mark all the property's getter method as #XmlTransient. Otherwise, JAXB throws an exception 2 properties found with the same name. Because our class all properties is visible to the JAXB. So we have to mark one as #XmlTransient.
In my opion, it is a better solution than the accepted answer. I gave all the credit to Sambit. I hove this will help others.

why do I get null when unmarshalling?

I am trying to read a XML file using JAXB, I'm also placing these into a list.
data code:
package xmll;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement(name="data")
public class data {
private int millis;
private String stamp;
private String datetime;
private int light;
private double temp;
private double vcc;
#XmlElement
public int getMillis() {
return millis;
}
public void setMillis(int millis) {
this.millis = millis;
}
#XmlElement
public String getStamp() {
return stamp;
}
public void setStamp(String stamp) {
this.stamp = stamp;
}
#XmlElement
public String getDatetime() {
return datetime;
}
public void setDatetime(String datetime) {
this.datetime = datetime;
}
#XmlElement
public int getLight() {
return light;
}
public void setLight(int light) {
this.light = light;
}
#XmlElement
public double getTemp() {
return temp;
}
public void setTemp(double temp) {
this.temp = temp;
}
#XmlElement
public double getVcc() {
return vcc;
}
public void setVcc(double vcc) {
this.vcc = vcc;
}
public data(int millis, String stamp, String datetime, int light, double temp, double vcc){
super();
this.millis = millis;
this.stamp = stamp;
this.datetime = datetime;
this.light = light;
this.temp = temp;
this.vcc = vcc;
}
public data(){
super();
}
datalist code:
public class DataList {
private List<data> listData = new ArrayList<data>();
#XmlElement(name="Data")
public List<data> getDataList(){
return listData;
}
public void setListData(List<data> listData) {
this.listData = listData;
}
}
Main code:
public class jaxb {
public static void main(String[] args)throws JAXBException, FileNotFoundException {
try {
JAXBContext jc = JAXBContext.newInstance(DataList.class);
Unmarshaller ums = jc.createUnmarshaller();
DataList dl = (DataList)ums.unmarshal(new File(".\\data\fridgelogdata.xml"));
System.out.println("the data bitch");
for (data d: dl.getDataList()){
System.out.println("millis=" + d.getMillis());
System.out.println("stamp=" + d.getStamp());
System.out.println("datetime=" + d.getDatetime());
System.out.println("light=" + d.getLight());
System.out.println("temp=" + d.getTemp());
System.out.println("vcc=" + d.getVcc());
}
} catch (Exception e) {
System.out.println(e.getMessage());
}
}
}
Does the problem lie within the actual xml file I'm using?
Thankful for any help :)
Here is the first row of xml, the xml file is quite large and includes thousand of rows so I cant display the whole file. Apologies for any beginner mistakes.
<?xml version="1.0" encoding="UTF-8"?>
<root>
<row>
<millis>1000</millis>
<stamp> 1273010254</stamp>
<datetime> 2010/5/4 21:57:34</datetime>
<light> 333</light>
<temp> 78.32</temp>
<vcc> 3.54</vcc>
</row>

Your xml is completely different to the annotations in your data and datalist code.
Considering xml
<?xml version="1.0" encoding="UTF-8"?>
<root>
<row>
<millis>1000</millis>
<stamp>1273010254</stamp>
<datetime>2010/5/4 21:57:34</datetime>
<light>333</light>
<temp>78.32</temp>
<vcc>3.54</vcc>
</row>
</root>
An correctly annotation class could be:
Root.java
#XmlAccessorType(XmlAccessType.FIELD)
#XmlType(name = "", propOrder = {
"row"
})
#XmlRootElement(name = "root")
public class Root {
#XmlElement(required = false)
protected List<Row> row;
public List<Row> getRow() {
if (row == null) {
row = new ArrayList<Row>();
}
return this.row;
}
#XmlAccessorType(XmlAccessType.FIELD)
#XmlType(name = "", propOrder = {
"millis",
"stamp",
"datetime",
"light",
"temp",
"vcc"
})
public static class Row {
protected Integer millis;
protected String stamp;
protected String datetime;
protected Integer light;
protected double temp;
protected double vcc;
public Integer getMillis() {
return millis;
}
public void setMillis(Integer value) {
this.millis = value;
}
public String getStamp() {
return stamp;
}
public void setStamp(String value) {
this.stamp = value;
}
//-...continue with the other getters and setters
}
}
EDIT Add method to unmarshall as asked in comment
JAXBContext jc = JAXBContext.newInstance(Root.class);
Unmarshaller ums = jc.createUnmarshaller();
Root root = (Root)ums.unmarshal(new File("pathToYourFile"));
for (Root.Row r: root.getRow()){
System.out.println("millis=" + r.getMillis());
//ecc...
}

JAXB getting original xml while unmarshalling for a list of elements

I have an xml input as below
<Confirmations>
<SystemConf>
<SysCnf>
<MessageId>1</MessageId>
</SysCnf>
<SysCnf>
<MessageId>2</MessageId>
</SysCnf>
</SystemConf>
</Confirmations>
and these are my classes
#XmlAccessorType(XmlAccessType.FIELD)
#XmlRootElement(name = "Confirmations")
public class Confirmations
{
#XmlElementWrapper(name = "SystemConf")
#XmlElement(name = "SysCnf")
private List<SystemConfirmation> systemConfirmations = null;
public List<SystemConfirmation> getSystemConfirmations()
{
return systemConfirmations;
}
public void setSystemConfirmations(List<SystemConfirmation> systemConfirmations)
{
this.systemConfirmations = systemConfirmations;
}
}
#XmlAccessorType(XmlAccessType.FIELD)
#XmlType(name = "SysCnf")
public class SystemConfirmation
{
#XmlElement(name = "MessageId")
private String messageId;
public void setMessageId(String messageId)
{
this.messageId = messageId;
}
public String getMessageId()
{
return messageId;
}
#XmlAnyElement(value = SysConfXmlStringHandler.class)
private String xml;
public String getXml()
{
return xml;
}
}
public class SysConfXmlStringHandler implements DomHandler<String, StreamResult>
{
private static final String SYSCONF_START_TAG = "<SycCnf>";
private static final String SYSCONF_END_TAG = "</SysCnf>";
private StringWriter xmlWriter = new StringWriter();
#Override
public StreamResult createUnmarshaller(ValidationEventHandler errorHandler)
{
return new StreamResult(xmlWriter);
}
#Override
public String getElement(StreamResult rt)
{
String xml = rt.getWriter().toString();
System.out.println(xml);
int beginIndex = xml.indexOf(SYSCONF_START_TAG) + SYSCONF_START_TAG.length();
int endIndex = xml.indexOf(SYSCONF_END_TAG);
return xml.substring(beginIndex, endIndex);
}
#Override
public Source marshal(String n, ValidationEventHandler errorHandler)
{
try
{
String xml = SYSCONF_START_TAG + n.trim() + SYSCONF_END_TAG;
StringReader xmlReader = new StringReader(xml);
return new StreamSource(xmlReader);
}
catch (Exception e)
{
throw new RuntimeException(e);
}
}
}
Question
In the xml field of the SystemConfirmation class I want the whole xml of that particular SystemConfirmation block xmml element, which would be below
<SysCnf>
<MessageId>1</MessageId>
</SysCnf>
Does anyone know how to achieve this? I tried the above code but I was only getting MessageId block in the xml and if I add multiple fields in SystemConfirmation than I only get the first one.

Simple-XML - how to serialize derived classes in a collection?

I want to serialize a object hierarchy including a list of objects which derive from the base class 'Thing'. This works fine, including deserialization - but XML-Simple insists in writing an attribute which specifies the actual used Java-class
when I create a xml file with the java code below, the content is like this:
<example1>
<things>
<fruit class="com.mumpitz.simplexmltest.Apple" id="17">
<sugar>212</sugar>
</fruit>
<fruit class="com.mumpitz.simplexmltest.Orange" id="25" weight="11.2"/>
</things>
</example1>
but this is not what I want.
I'd like to have
<example1>
<things>
<apple id="17">
<sugar>212</sugar>
</apple>
<orange id="25" weight="11.2"/>
</things>
</example1>
'apple' and 'orange' elements without a class attribute, not 'fruit' with such an attribute. Is this possible?
(The second xml complies to a existing schema; adding extra attributes is not an option)
Here's the code:
package com.mumpitz.simplexmltest;
import java.io.File;
import java.util.ArrayList;
import org.simpleframework.xml.Attribute;
import org.simpleframework.xml.Element;
import org.simpleframework.xml.ElementList;
import org.simpleframework.xml.Root;
import org.simpleframework.xml.Serializer;
import org.simpleframework.xml.core.Persister;
class Fruit {
#Attribute(name = "id")
protected final int id;
Fruit(
#Attribute(name = "id")
int id) {
this.id = id;
}
int getObjectId() {
return id;
}
}
#Root
class Apple extends Fruit {
private final int sugar;
#Element(type = Fruit.class)
public Apple(
#Attribute(name = "id")
int id,
#Element(name = "sugar")
int sugar) {
super(id);
this.sugar = sugar;
}
#Element(name = "sugar")
public int getSugar() {
return this.sugar;
}
#Override
public String toString() {
return "id: " + id + ", sugar: " + sugar;
}
}
#Root
class Orange extends Fruit {
#Attribute
public double weight;
public Orange(
#Attribute(name = "id")
int id) {
super(id);
}
#Override
public String toString() {
return "id: " + id + ", weight: " + weight;
}
}
#Root
public class Example1 {
#ElementList
public ArrayList<Fruit> things = new ArrayList<Fruit>();
#Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("things:\n");
for (int i=0; i<things.size(); i++) {
sb.append(" " + things.get(i).toString() + "\n");
}
return sb.toString();
}
//////////////////////////////////
static Example1 createDummy() {
Example1 d = new Example1();
d.things.add(new Apple(17, 212));
Orange or = new Orange(25);
or.weight = 11.2;
d.things.add(or);
return d;
}
static String msg;
static Example1 res;
static public String getMessage() {
String m = msg;
msg = null;
return m;
}
static public boolean write(String path) {
Serializer serializer = new Persister();
Example1 example = Example1.createDummy();
File result = new File(path);
try {
serializer.write(example, result);
} catch (Exception e) {
e.printStackTrace();
msg = e.getMessage();
return false;
}
return true;
}
static public boolean read(String path) {
Serializer serializer = new Persister();
File source = new File(path);
try {
res = serializer.read(Example1.class, source);
} catch (Exception e) {
e.printStackTrace();
msg = e.getMessage();
return false;
}
return true;
}
public static Object getResult() {
return res;
}
}

some hours later I found the solution. You simply have to
Read the manual
Use the #ElementListUnion annotation
package com.mumpitz.simplexmltest;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import org.simpleframework.xml.Attribute;
import org.simpleframework.xml.Element;
import org.simpleframework.xml.ElementList;
import org.simpleframework.xml.ElementListUnion;
import org.simpleframework.xml.Root;
import org.simpleframework.xml.Serializer;
import org.simpleframework.xml.core.Persister;
// the base class
#Element
class Thing {
static int count=0;
Thing() {
this.id = ++count;
}
#Attribute
protected int id;
public int getId() {
return id;
}
}
// first derived class
#Element
class Car extends Thing {
#Attribute
private String name;
Car(#Attribute(name="name") String name) {
this.name = name;
}
public String getName() {
return name;
}
#Override
public String toString() {
return "ID: " + id + " Car: " + name;
}
}
// second derived class
#Element
class House extends Thing {
#Attribute
private int price;
House(#Attribute(name="price") int price) {
this.price = price;
}
public int getPrice() {
return this.price;
}
#Override
public String toString() {
return "ID: " + id + " House: " + price;
}
}
// a class with a list of base class instances
#Root(name="ListOfThings")
public class Example4 {
// specify the derived classes used in the list
#ElementListUnion({
#ElementList(entry="house", inline=true, type=House.class),
#ElementList(entry="car", inline=true, type=Car.class)
})
private ArrayList<Thing> list = new ArrayList<Thing>();
public void add(Thing t) {
list.add(t);
}
public List<Thing> getProperties() {
return list;
}
#Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("Example4 contains " + list.size() + " elements:\n");
for (Thing t : list) {
sb.append(" " + t.toString() + "\n");
}
return sb.toString();
}
//////////////////////////////////
// test code
//////////////////////////////////
static String msg;
static Example4 res;
static public String getMessage() {
String m = msg;
msg = null;
return m;
}
static private Example4 createDummy() {
Example4 d = new Example4();
d.add(new Car("Mercedes"));
d.add(new House(34000000));
d.add(new Car("VW"));
d.add(new House(230000));
return d;
}
//////////////////////////////////
// serialize / deserialize
//////////////////////////////////
static public boolean write(String path) {
Serializer serializer = new Persister();
File result = new File(path);
Example4 example = Example4.createDummy();
try {
serializer.write(example, result);
} catch (Exception e) {
e.printStackTrace();
msg = e.getMessage();
return false;
}
return true;
}
static public boolean read(String path) {
Serializer serializer = new Persister();
File source = new File(path);
try {
res = serializer.read(Example4.class, source);
} catch (Exception e) {
e.printStackTrace();
msg = e.getMessage();
return false;
}
return true;
}
public static Object getResult() {
return res;
}
}