XML Parser

<?xml version="1.0" encoding="UTF-8"?>
        <project xmlns="http://maven.apache.org/POM/4.0.0"
                 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
            <modelVersion>4.0.0</modelVersion>
            <parent>
                <groupId>at.aydin.academy</groupId>
                <artifactId>30xmlparsers-pair</artifactId>
                <version>1.0.0</version>
                <relativePath>../pom.xml</relativePath>
            </parent>
            <artifactId>xml-stax-modern</artifactId>
            <packaging>jar</packaging>
            <name>XML StAX Modern</name>

            <dependencies>

<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter</artifactId>
    <scope>test</scope>
</dependency>

            </dependencies>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.apache.maven.plugins</groupId>
                        <artifactId>maven-compiler-plugin</artifactId>
                    </plugin>

                </plugins>
            </build>
        </project>

<orders><order id="1"><total>12.50</total></order><order id="2"><total>7.50</total></order></orders>

package at.aydin.lab.xmlparser.modern;

import java.io.InputStream;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamReader;

// Design Pattern: Iterator
// Zweck: Pull-Parsing verarbeitet große Dokumente ereignisweise mit konstantem Speicherbedarf.
public final class StaxOrderReader {
    public double total(InputStream inputStream) throws Exception {
        XMLInputFactory factory = XMLInputFactory.newFactory();
        factory.setProperty(XMLInputFactory.SUPPORT_DTD, false);
        factory.setProperty("javax.xml.stream.isSupportingExternalEntities", false);

        XMLStreamReader reader = factory.createXMLStreamReader(inputStream);
        double sum = 0;
        while (reader.hasNext()) {
            boolean totalElement = reader.next() == XMLStreamConstants.START_ELEMENT
                    && reader.getLocalName().equals("total");
            if (totalElement) {
                sum += Double.parseDouble(reader.getElementText());
            }
        }
        reader.close();
        return sum;
    }
}

package at.aydin.lab.xmlparser.modern;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;

class StaxOrderReaderTest {
    @Test
    void streamsEvents() throws Exception {
        try (var in = getClass().getResourceAsStream("/orders.xml")) {
            assertEquals(20, new StaxOrderReader().total(in));
        }
    }
}