Some Random and Important technical stuff

Some Random and Important technical stuff

public class DefaultedMap<K,V>
extends AbstractMapDecorator<K,V>
implements Serializable

Decorates another Map returning a default value if the map does not contain the requested key.

When the get(Object) method is called with a key that does not exist in the map, this map will return the default value specified in the constructor/factory. Only the get method is altered, so the Map.containsKey(Object) can be used to determine if a key really is in the map or not.

The defaulted value is not added to the map. Compare this behaviour with LazyMap, which does add the value to the map (via a Transformer).

For instance:

 Map map = new DefaultedMap("NULL");
 Object obj = map.get("Surname");
 // obj == "NULL"
 

After the above code is executed the map is still empty.

Note that DefaultedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedMap(Map). This class may throw exceptions when accessed by concurrent threads without synchronization.

About XML and XSD, Parsing, Marshalling and Unmarshalling of XML and XSD

- We should follow the sequence of elements of XSD while creating an xml file.

- How to parse, Unmarshall xml file? Sample code follows

     public Object parseXmlFromFile(Class messageClass, String xmlFile) throws JAXBException, FileNotFoundException {

return parse(messageClass, getXMLInputSourceFromFile(xmlFile));
}
protected Object parse(Class messageClass, InputSource xmlSource) throws JAXBException {
JAXBContext context = JAXBContext.newInstance(messageClass.getPackage().getName());
Unmarshaller unmarshaller = context.createUnmarshaller();
Object message = unmarshaller.unmarshal(xmlSource);

return message;
}

protected static InputSource getXMLInputSourceFromClasspath(String xmlFile) {

InputSource source = new InputSource(AbstractConfigResources.class.getResourceAsStream(xmlFile));
return source;
}

protected static InputSource getXMLInputSourceFromFile(String xmlFile) throws FileNotFoundException {

InputSource source = new InputSource(new FileInputStream(xmlFile));
return source;
}