XPath waluty v2 z ifem

ObslugaXML/src/main/java/przyklady_xpath/WalutyXPath2.java

+package przyklady_xpath;
+
+import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+import org.xml.sax.SAXException;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
+import java.io.IOException;
+
+public class WalutyXPath2 {
+
+    public static void main(String[] args) {
+        String szukanyKod = "USD";
+        // chcemy obliczyć średni kurs podanej waluty z całego pliku
+
+        System.out.println("Konfiguracja");
+        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+        XPathFactory xpf = XPathFactory.newInstance();
+        try {
+            XPath xpath = xpf.newXPath();
+            DocumentBuilder builder = factory.newDocumentBuilder();
+            System.out.println("Czytanie pliku");
+            Document doc = builder.parse("waluty_2022.xml");
+
+            System.out.println("Ewaluacja");
+            double suma = 0;
+            int ilosc = 0;
+            NodeList rates = (NodeList) xpath.evaluate("//Rate", doc, XPathConstants.NODESET);
+            final int nRates = rates.getLength();
+            for (int i = 0; i < nRates; i++) {
+                Node rate = rates.item(i);
+                String code = xpath.evaluate("Code", rate);
+                if(code.equalsIgnoreCase(szukanyKod)) {
+                    suma += (Double)xpath.evaluate("Mid", rate, XPathConstants.NUMBER);
+                    ilosc++;
+                    System.out.println(ilosc);
+                }
+            }
+            double srednia = suma / ilosc;
+            System.out.println("Średni kurs waluty " + szukanyKod + " = " + srednia);
+        } catch (ParserConfigurationException | SAXException | IOException | XPathExpressionException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}