VehicleReader.java

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package ns2;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.Map;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

public class VehicleReader {
    public static void read(
            String trace, 
            List<String> vehicleId, 
            Map<String, Double> vehicleFirstOcc, 
            Map<String, Double> vehicleLastOcc) {
        try {
            InputStream in = new FileInputStream(trace);
            XMLInputFactory factory = XMLInputFactory.newInstance();
            XMLStreamReader parser = factory.createXMLStreamReader(in);
            float time = -1;
            // parse trace file
            for (int event = parser.next(); event != XMLStreamConstants.END_DOCUMENT; event = parser.next()) {
                if (event == XMLStreamConstants.START_ELEMENT) {
                    // get current time
                    if (parser.getLocalName().equals("timestep")) {
                        for (int attr = 0; attr < parser.getAttributeCount(); attr++) {
                            String attrName = parser.getAttributeLocalName(attr);
                            String value = parser.getAttributeValue(attr);
                            if ("time".equals(attrName)) {
                                time = Float.parseFloat(value);
                            }
                        }
                    }
                    // vehicle element found
                    if (parser.getLocalName().equals("vehicle")) {
                        String id = "";
                        for (int attr = 0; attr < parser.getAttributeCount(); attr++) {
                            String attrName = parser.getAttributeLocalName(attr);
                            String value = parser.getAttributeValue(attr);
                            if ("id".equals(attrName)) {
                                id = value;
                            }
                        }
                        
                        // add id if not already added
                        if (!vehicleId.contains(id)) {
                            vehicleId.add(id);
                            // id is new -> first occurence of id
                            vehicleFirstOcc.put(id, new Double(time));
                        }
                        // maybe last occurence of id
                        vehicleLastOcc.put(id, new Double(time));
                    }
                }
            }
            parser.close();
        } catch (XMLStreamException ex) {
            System.err.println(ex);
        } catch (IOException ex) {
            System.err.println(ex);
        }
    }
}