This page summarizes most frequently asked questions for PlainXML. Please feel free to contact us if you have some specific question which is not listed here.

Which license is PlainXML released under?

PlainiXML is Open Source project. It is licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at Apache License 2.0 license. Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Which version of Java is required by PlainXML?

At least Java5 Standard Edition is required to compile and use PlainXML.

If I'd like to create class inherited from XML element manually, which methods should I override?

The following methods should be overriden in classes inherited from XMLElement (in other words, in ones which correspond to specific XML element):

  // attributes registration
  protected void init();
  // returns meta-type for XML element
  //(ones should be unique within a scheme)
  public int Type();
  // type of element content - may be one of
  public int ContentType();
  // returns DTD information for XML element
  public String GetDTDInfo();
   // returns name of XML element (name of tag)
  public String ElementName();
  // returns name of scheme which XML element
  // belongs to
  public String getSchemaID();
  public Object clone();
  // creates new instance of particular
  // XMLElement
  public static XMLElement newInstance();
Which basic types are supported for attributes?

The following basic types of XML attributes are supported:

  double (number separator in xml is "."),
  java.util.Date (in formats "M/dd/yyyy",
                  "M/dd/yyyy HH:mm:ss Z"
                  and "HH:mm:ss Z")

How typed property XXX should be defined for String attribute ?
  public static final String ATTR_XXX = "";
  public String getXXX(){
    return getAttrValue(ATTR_XXX);
  public void setXXX(String aValue){
    setAttrValue(ATTR_XXX, aValue);
How typed property YYY should be defined for int attribute xxx?
  public static final String ATTR_YYY = "xxx";
  public int getXXX(){
     return getAttrValueAsInt(ATTR_YYY, Integer.MIN_VALUE);
  public int getXXX(int aDefaultValue){
     return getAttrValueAsInt(ATTR_YYY, aDefaultValue);
  public void setXXX(int aValue){
    if (aValue != Integer.MIN_VALUE)
      setAttrValueAsInt(ATTR_YYY, aValue);
     setAttrValue(ATTR_YYY, null);
How typed property ZZZ should be defined for number (with specified precision) attribute xxx?
  public static final String ATTR_ZZZ = "xxx";
  public double getXXX(){
     // 3 is amount of digits after
     // dot 
     return getAttrValueAsNumber(ATTR_ZZZ, 3, Double.NaN);
  public double getXXX(double aDefaultValue){
    return getAttrValueAsNumber(ATTR_ZZZ, 3, aDefaultValue);
  public void setXXX(double aValue){
    if (Double.isNaN(aValue))
      setAttrValue(ATTR_ZZZ, null);
      setAttrValueAsNumber(ATTR_ZZZ, aValue, 3);
How typed property DDD should be defined for java.util.Date attribute xxx?
  public static final String ATTR_DDD = "xxx";
  public Date getXXX(){
    return getAttrValueAsDate(ATTR_DDD, null);
  public void setXXX(String aValue){
     if (aValue != null)
       setAttrValueAsDate(ATTR_DDD, aValue);
       setAttrValue(ATTR_DDD, null);   
How typed property BBB should be defined for boolean attribute xxx which may have values ("yes" and "no")?
  public static final String ATTR_BBB = "bbb";
  public boolean isXXX(){
    return isAttrValueYes(ATTR_BBB);
  public void setXXX(Boolean aValue){
    if (aValue != null)
          setAttrValueAsBoolean(ATTR_BBB, aValue);
          setAttrValue(ATTR_BBB, null);
How to obtain original String value of attribute using generic methods (not using typed properties)?

  // or it's possible to check
  // whether attribute value is
  // "yes" or "no" 
For some reasons, DTD don't include some attribute but I'd like to assign it to particular element?

The internal structure of XMLElement is quite flexible and allows to dynamicall add even unknown attributes and elements. This allows to have very convenient mechanism in algorythms which perfom various manipulation with XML - for example, one part of algoritym may add additional information to XML element via their attributes (either as some processing hints or data to process ) which will be passed along with XMLElement instance to further processing. Adding new "unregistered" attributed to XML element is pretty simple and could be done in the way illustrated below:

  // "true" parameter indicates
  // that if element was not
  // registered, it should be
  // added dynamically
  this.setAttrValue(Attr_Name, Attr_Value, true);
How can I work with PCDATA of xml element?

PCDATA value which is stored in XML element may be accessed by the following methods (please note that base64binary is also supported and that CDATA encoding is also supported).

  // obtaining PCDATA
  String val = this.getPCData();

  // setting PCDATA value
  // Last parameters indicates whether PCDATA
  // should be encoded as CDATA
  this.setPCData(val, true);

  // obtaining PCDATA
  // as Base64 binary
  byte[] base64 = this.getBase64Binary();
How property which represents contained element should be written if this element may be included more than one time?
  public XmlObjXXX getFirstObjXXX(){
    XmlObjXXX result = null;
    int index = findFirst(XmlObjXXX.TYPE_ID);
    if (index != -1)
      result = (XmlObjXXX) Items().get(index);
    return result;
   public XmlObjXXX getLastObjXXX(){
     XmlObjXXX result = null;
     int index = findLast(XmlObjXXX.TYPE_ID);
     if (index != -1)
       result = (XmlObjXXX) Items().get(index);
     return result;
   public Iterable<XmlObjXXX> getAllObjXXXs(){
     return new ItemIterable<XmlObjXXX>(XmlObjXXX.TYPE_ID);
How property which represents contained element should be written if this element may be included into tag only once?
  public XmlSomeObject getSomeObject(){
    XmlSomeObject result = null;
    int index = findFirst(XmlSomeObject.TYPE_ID);
    if (index != -1)
      result = (XmlSomeObject) Items().get(index);
    return result;
  public void setSomeObject(XmlSomeObjectl elm){
    setFirstItem(XmlSomeObject.TYPE_ID, elm);
What can I create ListIterator which returns only specified elements (xxx)?

It is possible to create ListIterator which will return only specific XML elements:

  ListIterator<XMLElement> itr =
     new ItemItr<XMLElement>(new AcceptBy("xxx"));    
How can I remove all sub-elements with type xxx which have specific value of attribute?

Child XML elements with specific type could be removed from XML element as it's shown by code below:

  ListIterator<XMLElement> itr =
    new ItemItr<XMLElement>(new AcceptBy("xxx"));
    XMLElement elm =;
    String attrValue = elm.getAttrValue("yyy");
    if ("zzz".equals(attrValue)){
How to directly access all children of element?

Child XML elements could be directly accessed via appropriate property:

    List<XMLElement> items = this.Items();
How to obtain collection of child elements which name starts from "abc" and which has attributes which ends with "efg" and iterate over it?

The following code snippet illustrates select child XML elements by pattern and iterate over them.

    // either using iterator ...
    IElementAcceptor acceptor =
      new AcceptBy("abc*", "*efg", null);
    ListIterator<XMLElement> itr =
      new ItemItr<XMLElement>(acceptor);
      XMLElement elm =;
    // ... or using iterable
    IElementAcceptor acceptor =
      new AcceptBy("abc*", "*efg");
    Iterable<XMLElement> itr =
      new ItemIterable<XMLElement>(acceptor);
    for (XMLElement elm: itr){
How to sort child elements by value of attribute "yyy"?

Child xml elements could be sorted by the following code.

  List<XMLElement> items = this.Items();
  Collections.sort(items, new CompareBy("yyy"));
Are wildcards supported by "isMatch" method?

Yes, it's possible to specify wildcard expression as attribute of method. The following types of wildcards are supported:
xxx* String which starts from "xxx"
*xxx* String which contains "xxx"
*xxx String whih ends with "xxx"
xxx Exact match

How to copy attributes values from one instance of element to another one?

The following example illustrates how copy values of attributes from one XML element to another one.

  XmlSomeObj src ....;
  XmlSomeObj dest = XmlSomeObj.newInstance();
  // true indicates that child
  // elements should be copied
  // too (as shallow copy)
  dest.assignFrom(src, true);
How can I track modifications of element structure?

Your code may be notified about changes in element structure of attributes if the following methods are overriden:

   protected boolean acceptAddChild(XMLElement aElement);
   protected boolean acceptChangeAttrValue(String aAttName,
             String aOldValue, String aNewValue);
   protected boolean acceptRemoveChild(XMLElement aElement);
How restore DTD definition by existing instance of element?

The following code snippet illustrates how to restore DTD definition by existing XML element.

   XMLElementInfo elmInfo = new XMLElementInfo(aXMLElement);
   String dtdInfo = elmInfo.toText();
How read XML tree composed by typed XML elements of there are reader (factory) for particular XML scheme?

The following code snippet illustrates how to read POJO XML tree from file.

    FileInputStream  fis = new FileInputStream(aFile);
    if (fis != null){
      InputStreamReader isr =
        new InputStreamReader(fis, "UTF-8");
      Reader reader = new BufferedReader(isr);
      XMLReader docHandler = new XXXReader();
        XMLParser.parse(docHandler, reader);
        // XmlXXX - root for schema XXX
        root = (XmlXXXRoot) docHandler.getRoot();
      //close IO resources
How can I write POJO tree in binary XML format?

The following example illustrates how to write POJO objects to binary XML format.

    ObjectOutput oos = new ObjectOutputStream(...);
    // xmlData contains root of
    // xml tree and is used for
    // custom XML marshalling/unmarshalling
    // using binary or plain format
    XMLData xmlData = new XMLData();
    // Write to binary XML format
How can I read POJO tree from binary XML format?

The following example illustrates how to read POJO objects from binary XML format.

    ObjectInput ois = new ObjectInputStream(...);
    // xmlData contains root of
    // xml tree and is used for
    // custom XML marshalling/unmarshalling
    // using binary or plain format
    XMLData xmlData = new XMLData();
    // Read from binary XML format
    XMLElement root = xmlData.getRoot();
How can I export POJO XML tree to JSON?

The following example illustrates how to write XML tree to JSON (JavaScript Object Notation).

    OutputStreamWriter osw = new OutputStreamWriter(os);
    Writer wout = new BufferedWriter(osw);
    // Here we create JSONWriter
    JSONWriter json = new JSONWriter();

    // And specify settings
    // which control output details,
    // if necessary

    // Also, if necessary,
    // we could specify element
    // names substitution map
    json.replaceElementName("var", "macro");

    // And finally, here
    // we initiate export
    json.write(wout, journal);
What should I do if I found a bug?

Let us know it! Please submit bugs and feature ideas or patches to the email [email protected], and we’ll get on it.

I have some question or suggestion regarding PlainXML. How could I submit them to you?

Please do not hesitate contacting us if you have any questions, comments, suggestions or simply find some issues with PlainXML. Please send us your feedback via email using [email protected] email addresss. Logo   Support This Project