I have xml as below.
<Employees>
<Employee id="1">Chuck</Employee>
<Employee id="2">Al</Employee>
<Employee id="3">Kiran</Employee>
</Employees>
XML contains huge number of employees.I have mentioned only for simplification.
What is the best way to parse this xml and populate into a map? Map should contain id and name pairs.
Please provide code for better understanding.
The XStream answer seems like a lot of code. You could do something like the following with the StAX APIs in the JDK/JRE:
package forum11871952;
import java.io.FileReader;
import java.util.*;
import javax.xml.stream.*;
public class Demo {
public static void main(String[] args) throws Exception {
XMLInputFactory xif = XMLInputFactory.newFactory();
XMLStreamReader xsr = xif.createXMLStreamReader(new FileReader("src/forum11871952/input.xml"));
xsr.nextTag(); // advance to Employees tag
xsr.nextTag(); // advance to first Employer element
Map<String,String> map = new HashMap<String,String>();
while(xsr.getLocalName().equals("Employee")) {
map.put(xsr.getAttributeValue("", "id"), xsr.getElementText());
xsr.nextTag(); // advance to next Employer element
}
}
}
We can simply map this using Xstream.
XStream xStream = new XStream(new DomDriver());
xStream.alias("Employees", Employees.class);
xStream.registerConverter(new MapEntryConverter());
employeesMap = (Map<String, String>) xStream.fromXML(queryXML);
Create a converter which unmarshall XML to Map object
private static class MapEntryConverter implements Converter {
public boolean canConvert(Class clazz) {
return clazz.equals(Employees.class);
}
public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) {
AbstractMap<String, String> map = (AbstractMap<String, String>) value;
for (Map.Entry<String, String> entry : map.entrySet()) {
writer.startNode(entry.getKey().toString());
writer.setValue(entry.getValue().toString());
writer.endNode();
}
}
public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
Map<String, String> map = new HashMap<String, String>();
while (reader.hasMoreChildren()) {
reader.moveDown();
map.put(reader.getAttribute(1), reader.getValue());
reader.moveUp();
}
return map;
}
}
Create Employees and Employee classes as below.
private class Employees{
List<Employee> employees;
}
private class Employee{
private String id;
private String value;
}
Hope this works for you.
Use a library such as XStream. List<Employee> suits better than a Map here.
List is better than a Map if OP doesn't care about lookup times.
Set over both List or Map
Map<String, Integer>.