Parse XML using JAXB

Question

I have created the following XML using JAXB classes created from an XSD. I now want to use them to parse XML. The XML elements Screens, DBSession and CLISession are optional and can be used in any order.

<Test>
  <Screens>
    <Screen attr1="qw" attr2="ds" attr3="sdf"></Screen>
  </Screens>
  <DBSession attr1="sd" attr2="sdf" attr3="sdf"></DBSession>
  <CLISession attr1="sdf"></CLISession>
  <Screens>
    <Screen attr1="qdw" attr2="dss" attr3="a"></Screen>
  </Screens>
</Test>

I have a class in the file Test.java which contains the following method:

public List<Object> getCLISessionOrDBSessionOrScreens() {
  if (cliSessionOrDBSessionOrScreens == null) {
    cliSessionOrDBSessionOrScreens = new ArrayList<Object>();
  }
  return this.cliSessionOrDBSessionOrScreens;
}

I also have the following Java classes which contains methods to get the values of the attributes.

ScreenType.java
CLISissionType.java
DBSessionType.java

Using the code below I am trying to parse the XML and am able to identify the elements cliSession, DBSession and Screens and their order but I am unable to get a handle on them to call the necessary methods in the classes ScreenType.java, CLISissionType.java, DBSessionType.java. How do I edit this code to access the methods in these Java files?

JAXBContext jaxbContext = JAXBContext.newInstance("com.qa.xmlgenerator.model.generatedxmlclasses");
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
StringReader reader = new StringReader(xml);
JAXBElement<?> test = (JAXBElement<?>) unmarshaller.unmarshal(reader);
Test testInfo = (Test) test.getValue();

int numComponents = testInfo.getCLISessionOrDBSessionOrScreens().size();
for(int i= 0; i<numComponents; i++){
  System.out.println(testInfo.getCLISessionOrDBSessionOrScreens().get(i));
}

This is the output from the System.out.println in the above code:

com.q1labs.qa.xmlgenerator.model.generatedxmlclasses.ScreensType@1a8b2725
com.q1labs.qa.xmlgenerator.model.generatedxmlclasses.DBSessionType@25b6fbc0
com.q1labs.qa.xmlgenerator.model.generatedxmlclasses.CLISessionType@104a0d98
com.q1labs.qa.xmlgenerator.model.generatedxmlclasses.ScreensType@6dc27e82

Answer 1

Try this:

if(testInfo.getCLISessionOrDBSessionOrScreens().get(i) instanceof ScreensType)
{
    ScreensType screenTypeObj = (ScreensType) testInfo.getCLISessionOrDBSessionOrScreens().get(i);
    screenTypeObj.callYourDesiredMethod();
}

Similarly you can call others by checking their types and casting them to suitable Class and finally calling your desired methods.